Add project which uses OPC-UA to talk to coupler. Based on modbus one.

Beremiz/beremiz_tutorial_opc_ua/beremiz.xml

+<?xml version='1.0' encoding='utf-8'?>
+<BeremizRoot xmlns:xsd="http://www.w3.org/2001/XMLSchema" URI_location="LOCAL://">
+  <TargetType/>
+</BeremizRoot>

Beremiz/beremiz_tutorial_opc_ua/build/LOCATED_VARIABLES.h

+__LOCATED_VAR(BOOL,__QX0_0_0_0,Q,X,0,0,0,0)
+__LOCATED_VAR(BOOL,__QX0_0_1_1,Q,X,0,0,1,1)
+__LOCATED_VAR(BOOL,__QX0_0_2_2,Q,X,0,0,2,2)
+__LOCATED_VAR(BOOL,__QX0_0_3_3,Q,X,0,0,3,3)
+__LOCATED_VAR(DINT,__QD1_0,Q,D,1,0)

Beremiz/beremiz_tutorial_opc_ua/build/MB_0.c

+/* File generated by Beremiz (PlugGenerate_C method of Modbus plugin) */
+
+/*
+ * Copyright (c) 2016 Mario de Sousa (msousa@fe.up.pt)
+ *
+ * This file is part of the Modbus library for Beremiz and matiec.
+ *
+ * This Modbus library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser 
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this Modbus library.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * This code is made available on the understanding that it will not be
+ * used in safety-critical situations without a full and competent review.
+ */
+
+
+#include <stdio.h>
+#include <string.h>  /* required for memcpy() */
+#include <errno.h>
+#include <time.h>
+#include <signal.h>
+#include <unistd.h>  /* required for pause() */
+#include "mb_slave_and_master.h"
+#include "MB_0.h"
+
+
+#define MAX_MODBUS_ERROR_CODE 11
+static const char *modbus_error_messages[MAX_MODBUS_ERROR_CODE+1] = {
+    /* 0 */ "",                             /* un-used -> no error! */
+    /* 1 */ "illegal/unsuported function",
+    /* 2 */ "illegal data address",
+    /* 3 */ "illegal data value",
+    /* 4 */ "slave device failure",
+    /* 5 */ "acknowledge -> slave intends to reply later",
+    /* 6 */ "slave device busy",
+    /* 7 */ "negative acknowledge",
+    /* 8 */ "memory parity error",
+    /* 9 */ "",                             /* undefined by Modbus */
+    /* 10*/ "gateway path unavalilable",
+    /* 11*/ "gateway target device failed to respond"
+};    
+
+
+/* Execute a modbus client transaction/request */
+static int __execute_mb_request(int request_id){
+	switch (client_requests[request_id].mb_function){
+	
+	case  1: /* read coils */
+		return read_output_bits(client_requests[request_id].slave_id,
+					client_requests[request_id].address,
+					client_requests[request_id].count,
+					client_requests[request_id].coms_buffer,
+					(int) client_requests[request_id].count,
+					client_nodes[client_requests[request_id].client_node_id].mb_nd,
+					client_requests[request_id].retries,
+					&(client_requests[request_id].mb_error_code),
+					&(client_requests[request_id].resp_timeout),
+					&(client_requests[request_id].coms_buf_mutex));
+
+	case  2: /* read discrete inputs */
+		return read_input_bits( client_requests[request_id].slave_id,
+					client_requests[request_id].address,
+					client_requests[request_id].count,
+					client_requests[request_id].coms_buffer,
+					(int) client_requests[request_id].count,
+					client_nodes[client_requests[request_id].client_node_id].mb_nd,
+					client_requests[request_id].retries,
+					&(client_requests[request_id].mb_error_code),
+					&(client_requests[request_id].resp_timeout),
+					&(client_requests[request_id].coms_buf_mutex));
+
+	case  3: /* read holding registers */
+		return read_output_words(client_requests[request_id].slave_id,
+					client_requests[request_id].address,
+					client_requests[request_id].count,
+					client_requests[request_id].coms_buffer,
+					(int) client_requests[request_id].count,
+					client_nodes[client_requests[request_id].client_node_id].mb_nd,
+					client_requests[request_id].retries,
+					&(client_requests[request_id].mb_error_code),
+					&(client_requests[request_id].resp_timeout),
+					&(client_requests[request_id].coms_buf_mutex));
+	
+	case  4: /* read input registers */
+		return read_input_words(client_requests[request_id].slave_id,
+					client_requests[request_id].address,
+					client_requests[request_id].count,
+					client_requests[request_id].coms_buffer,
+					(int) client_requests[request_id].count,
+					client_nodes[client_requests[request_id].client_node_id].mb_nd,
+					client_requests[request_id].retries,
+					&(client_requests[request_id].mb_error_code),
+					&(client_requests[request_id].resp_timeout),
+					&(client_requests[request_id].coms_buf_mutex));
+
+	case  5: /* write single coil */
+		return write_output_bit(client_requests[request_id].slave_id,
+					client_requests[request_id].address,
+					client_requests[request_id].coms_buffer[0],
+					client_nodes[client_requests[request_id].client_node_id].mb_nd,
+					client_requests[request_id].retries,
+					&(client_requests[request_id].mb_error_code),
+					&(client_requests[request_id].resp_timeout),
+					&(client_requests[request_id].coms_buf_mutex));
+
+	case  6: /* write single register */
+		return write_output_word(client_requests[request_id].slave_id,
+					client_requests[request_id].address,
+					client_requests[request_id].coms_buffer[0],
+					client_nodes[client_requests[request_id].client_node_id].mb_nd,
+					client_requests[request_id].retries,
+					&(client_requests[request_id].mb_error_code),
+					&(client_requests[request_id].resp_timeout),
+					&(client_requests[request_id].coms_buf_mutex));
+
+	case  7: break; /* function not yet supported */
+	case  8: break; /* function not yet supported */
+	case  9: break; /* function not yet supported */
+	case 10: break; /* function not yet supported */
+	case 11: break; /* function not yet supported */
+	case 12: break; /* function not yet supported */
+	case 13: break; /* function not yet supported */
+	case 14: break; /* function not yet supported */
+	
+	case 15: /* write multiple coils */
+		return write_output_bits(client_requests[request_id].slave_id,
+					 client_requests[request_id].address,
+					 client_requests[request_id].count,
+					 client_requests[request_id].coms_buffer,
+					 client_nodes[client_requests[request_id].client_node_id].mb_nd,
+					 client_requests[request_id].retries,
+					 &(client_requests[request_id].mb_error_code),
+					 &(client_requests[request_id].resp_timeout),
+					 &(client_requests[request_id].coms_buf_mutex));
+
+	case 16: /* write multiple registers */
+		return write_output_words(client_requests[request_id].slave_id,
+					client_requests[request_id].address,
+					client_requests[request_id].count,
+					client_requests[request_id].coms_buffer,
+					client_nodes[client_requests[request_id].client_node_id].mb_nd,
+					client_requests[request_id].retries,
+					&(client_requests[request_id].mb_error_code),
+					&(client_requests[request_id].resp_timeout),
+					&(client_requests[request_id].coms_buf_mutex));
+	
+	default: break;  /* should never occur, if file generation is correct */
+	}
+
+	fprintf(stderr, "Modbus plugin: Modbus function %d not supported\n", request_id); /* should never occur, if file generation is correct */
+	return -1;
+}
+
+
+
+/* pack bits from unpacked_data to packed_data */
+static inline int __pack_bits(u16 *unpacked_data, u16 start_addr, u16 bit_count,  u8  *packed_data) {
+  u8 bit;
+  u16 byte, coils_processed;
+
+  if ((0 == bit_count) || (65535-start_addr < bit_count-1))
+    return -ERR_ILLEGAL_DATA_ADDRESS; /* ERR_ILLEGAL_DATA_ADDRESS defined in mb_util.h */
+  
+  for( byte = 0, coils_processed = 0; coils_processed < bit_count; byte++) {
+    packed_data[byte] = 0;
+    for( bit = 0x01; (bit & 0xFF) && (coils_processed < bit_count); bit <<= 1, coils_processed++ ) {
+      if(unpacked_data[start_addr + coils_processed])
+            packed_data[byte] |=  bit; /*   set bit */
+      else  packed_data[byte] &= ~bit; /* reset bit */
+    }
+  }
+  return 0;
+}
+
+
+/* unpack bits from packed_data to unpacked_data */
+static inline int __unpack_bits(u16 *unpacked_data, u16 start_addr, u16 bit_count,  u8  *packed_data) {
+  u8  temp, bit;
+  u16 byte, coils_processed;
+
+  if ((0 == bit_count) || (65535-start_addr < bit_count-1))
+    return -ERR_ILLEGAL_DATA_ADDRESS; /* ERR_ILLEGAL_DATA_ADDRESS defined in mb_util.h */
+  
+  for(byte = 0, coils_processed = 0; coils_processed < bit_count; byte++) {
+    temp = packed_data[byte] ;
+    for(bit = 0x01; (bit & 0xff) && (coils_processed < bit_count); bit <<= 1, coils_processed++) {
+      unpacked_data[start_addr + coils_processed] = (temp & bit)?1:0;
+    }
+  }
+  return 0;
+}
+
+
+static int __read_inbits   (void *mem_map, u16 start_addr, u16 bit_count, u8  *data_bytes) {
+  int res = __pack_bits(((server_mem_t *)mem_map)->ro_bits, start_addr, bit_count, data_bytes);
+  
+  if (res >= 0) {
+    /* update the flag and counter of Modbus requests we have processed. */
+    ((server_mem_t *)mem_map)->flag_read_req_counter++;
+    ((server_mem_t *)mem_map)->flag_read_req_flag = 1;
+  }
+
+  return res;
+}
+
+static int __read_outbits  (void *mem_map, u16 start_addr, u16 bit_count, u8  *data_bytes) {
+  int res = __pack_bits(((server_mem_t *)mem_map)->rw_bits, start_addr, bit_count, data_bytes);
+  
+  if (res >= 0) {
+    /* update the flag and counter of Modbus requests we have processed. */
+    ((server_mem_t *)mem_map)->flag_read_req_counter++;
+    ((server_mem_t *)mem_map)->flag_read_req_flag = 1;
+  }
+
+  return res;
+}
+
+static int __write_outbits (void *mem_map, u16 start_addr, u16 bit_count, u8  *data_bytes) {
+  int res = __unpack_bits(((server_mem_t *)mem_map)->rw_bits, start_addr, bit_count, data_bytes);
+  
+  if (res >= 0) {
+    /* update the flag and counter of Modbus requests we have processed. */
+    ((server_mem_t *)mem_map)->flag_write_req_counter++;
+    ((server_mem_t *)mem_map)->flag_write_req_flag = 1;
+  }
+
+  return res;
+}
+
+
+
+
+static int __read_inwords  (void *mem_map, u16 start_addr, u16 word_count, u16 *data_words) {
+
+  if ((start_addr + word_count) > MEM_AREA_SIZE)
+    return -ERR_ILLEGAL_DATA_ADDRESS; /* ERR_ILLEGAL_DATA_ADDRESS defined in mb_util.h */
+
+  /* update the flag and counter of Modbus requests we have processed. */
+  ((server_mem_t *)mem_map)->flag_read_req_counter++;
+  ((server_mem_t *)mem_map)->flag_read_req_flag = 1;
+
+  /* use memcpy() because loop with pointers (u16 *) caused alignment problems */
+  memcpy(/* dest */ (void *)data_words,
+         /* src  */ (void *)&(((server_mem_t *)mem_map)->ro_words[start_addr]),
+         /* size */ word_count * 2);
+  return 0;
+}
+
+
+
+static int __read_outwords (void *mem_map, u16 start_addr, u16 word_count, u16 *data_words) {
+
+  if ((start_addr + word_count) > MEM_AREA_SIZE)
+    return -ERR_ILLEGAL_DATA_ADDRESS; /* ERR_ILLEGAL_DATA_ADDRESS defined in mb_util.h */
+
+  /* update the flag and counter of Modbus requests we have processed. */
+  ((server_mem_t *)mem_map)->flag_read_req_counter++;
+  ((server_mem_t *)mem_map)->flag_read_req_flag = 1;
+
+  /* use memcpy() because loop with pointers (u16 *) caused alignment problems */
+  memcpy(/* dest */ (void *)data_words,
+         /* src  */ (void *)&(((server_mem_t *)mem_map)->rw_words[start_addr]),
+         /* size */ word_count * 2);
+  return 0;
+}
+
+
+
+
+static int __write_outwords(void *mem_map, u16 start_addr, u16 word_count, u16 *data_words) {
+
+  if ((start_addr + word_count) > MEM_AREA_SIZE)
+    return -ERR_ILLEGAL_DATA_ADDRESS; /* ERR_ILLEGAL_DATA_ADDRESS defined in mb_util.h */
+
+  /* update the flag and counter of Modbus requests we have processed. */
+  ((server_mem_t *)mem_map)->flag_write_req_counter++;
+  ((server_mem_t *)mem_map)->flag_write_req_flag = 1;
+
+  /* WARNING: The data returned in the data_words[] array is not guaranteed to be 16 bit aligned.
+   *           It is not therefore safe to cast it to an u16 data type.
+   *           The following code cannot be used. memcpy() is used instead.
+   */
+  /*
+  for (count = 0; count < word_count ; count++)
+    ((server_mem_t *)mem_map)->rw_words[count + start_addr] = data_words[count];
+  */
+  memcpy(/* dest */ (void *)&(((server_mem_t *)mem_map)->rw_words[start_addr]),
+         /* src  */ (void *)data_words,
+         /* size */ word_count * 2);
+  return 0;
+}
+
+
+
+
+#include <pthread.h>
+
+static void *__mb_server_thread(void *_server_node)  {
+	server_node_t *server_node = _server_node;
+	mb_slave_callback_t callbacks = { 
+			&__read_inbits,
+			&__read_outbits,
+			&__write_outbits,
+			&__read_inwords,
+			&__read_outwords,
+			&__write_outwords,
+			(void *)&(server_node->mem_area)
+			};  
+	
+	// Enable thread cancelation. Enabled is default, but set it anyway to be safe.
+	pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
+
+	// mb_slave_run() should never return!
+	mb_slave_run(server_node->mb_nd /* nd */, callbacks, server_node->slave_id);
+	fprintf(stderr, "Modbus plugin: Modbus server for node %s died unexpectedly!\n", server_node->location); /* should never occur */
+	return NULL;
+}
+
+
+#define timespec_add(ts, sec, nsec) {		\
+	ts.tv_sec  +=  sec;			\
+	ts.tv_nsec += nsec;			\
+	if (ts.tv_nsec >= 1000000000) {		\
+		ts.tv_sec  ++;			\
+		ts.tv_nsec -= 1000000000;	\
+	}					\
+}
+
+
+static void *__mb_client_thread(void *_index)  {
+	int client_node_id = (char *)_index - (char *)NULL; // Use pointer arithmetic (more portable than cast)
+
+	// Enable thread cancelation. Enabled is default, but set it anyway to be safe.
+	pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
+	
+    /* loop the communication with the client
+     * 
+         * When the client thread has difficulty communicating with remote client and/or server (network issues, for example),
+         * then the communications get delayed and we will fall behind in the period. 
+         * 
+         * This is OK. Note that if the condition variable were to be signaled multiple times while the client thread is inside the same
+         * Modbus transaction, then all those signals would be ignored.
+         * However, and since we keep the mutex locked during the communication cycle, it is not possible to signal the condition variable
+         * during that time (it is only possible while the thread is blocked during the call to pthread_cond_wait().
+         * 
+         * This means that when network issues eventually get resolved, we will NOT have a bunch of delayed activations to handle
+         * in quick succession (which would goble up CPU time). 
+         * 
+         * Notice that the above property is valid whether the communication cycle is run with the mutex locked, or unlocked.
+         * Since it makes it easier to implement the correct semantics for the other activation methods if the communication cycle
+         * is run with the mutex locked, then that is what we do.
+         * 
+     * Note that during all the communication cycle we will keep locked the mutex 
+     * (i.e. the mutex used together with the condition variable that will activate a new communication cycle)
+     * 
+     * Note that we never get to explicitly unlock this mutex. It will only be unlocked by the pthread_cond_wait()
+     * call at the end of the cycle.
+     */
+    pthread_mutex_lock(&(client_nodes[client_node_id].mutex));
+
+	while (1) {
+		/*
+		struct timespec cur_time;
+		clock_gettime(CLOCK_MONOTONIC, &cur_time);
+		fprintf(stderr, "Modbus client thread (%d) - new cycle (%ld:%ld)!\n", client_node_id, cur_time.tv_sec, cur_time.tv_nsec);
+		*/
+		int req;
+		for (req=0; req < NUMBER_OF_CLIENT_REQTS; req ++){
+			/* just do the requests belonging to the client */
+			if (client_requests[req].client_node_id != client_node_id)
+				continue;
+            
+            /* only do the request if:
+             *   - this request was explictly asked to be executed by the client program
+             *  OR
+             *   - the client thread was activated periodically
+             *     (in which case we execute all the requests belonging to the client node)
+             */
+            if ((client_requests[req].flag_exec_req == 0) && (client_nodes[client_requests[req].client_node_id].periodic_act == 0))
+                continue;
+            
+            /*
+            fprintf(stderr, "Modbus client thread (%d): RUNNING Modbus request %d  (periodic = %d  flag_exec_req = %d)\n", 
+                    client_node_id, req, client_nodes[client_requests[req].client_node_id].periodic_act, client_requests[req].flag_exec_req );
+            */
+            
+			int res_tmp = __execute_mb_request(req);
+			client_requests[req].tn_error_code = 0; // assume success
+			switch (res_tmp) {
+			  case PORT_FAILURE: {
+				if (res_tmp != client_nodes[client_node_id].prev_error)
+					fprintf(stderr, "Modbus plugin: Error connecting Modbus client %s to remote server.\n", client_nodes[client_node_id].location);
+				client_nodes[client_node_id].prev_error = res_tmp;
+				client_requests[req].tn_error_code = 1; // error accessing IP network, or serial interface
+				break;
+			  }
+			  case INVALID_FRAME: {
+				if ((res_tmp != client_requests[req].prev_error) && (0 == client_nodes[client_node_id].prev_error))
+					fprintf(stderr, "Modbus plugin: Modbus client request configured at location %s was unsuccesful. Server/slave returned an invalid/corrupted frame.\n", client_requests[req].location);
+				client_requests[req].prev_error = res_tmp;
+				client_requests[req].tn_error_code = 2; // reply received from server was an invalid frame
+				break;
+			  }
+			  case TIMEOUT: {
+				if ((res_tmp != client_requests[req].prev_error) && (0 == client_nodes[client_node_id].prev_error))
+					fprintf(stderr, "Modbus plugin: Modbus client request configured at location %s timed out waiting for reply from server.\n", client_requests[req].location);
+				client_requests[req].prev_error = res_tmp;
+				client_requests[req].tn_error_code = 3; // server did not reply before timeout expired
+				break;
+			  }
+			  case MODBUS_ERROR: {
+				if (client_requests[req].prev_error != client_requests[req].mb_error_code) {
+					fprintf(stderr, "Modbus plugin: Modbus client request configured at location %s was unsuccesful. Server/slave returned error code 0x%2x", client_requests[req].location, client_requests[req].mb_error_code);
+					if (client_requests[req].mb_error_code <= MAX_MODBUS_ERROR_CODE ) {
+						fprintf(stderr, "(%s)", modbus_error_messages[client_requests[req].mb_error_code]);
+						fprintf(stderr, ".\n");
+					}
+				}
+				client_requests[req].prev_error = client_requests[req].mb_error_code;
+				client_requests[req].tn_error_code = 4; // server returned a valid Modbus error frame
+				break;
+			  }
+			  default: {
+				if ((res_tmp >= 0) && (client_nodes[client_node_id].prev_error != 0)) {
+					fprintf(stderr, "Modbus plugin: Modbus client %s has reconnected to server/slave.\n", client_nodes[client_node_id].location);
+				}
+				if ((res_tmp >= 0) && (client_requests[req]        .prev_error != 0)) {
+					fprintf(stderr, "Modbus plugin: Modbus client request configured at location %s has succesfully resumed comunication.\n", client_requests[req].location);
+				}
+				client_nodes[client_node_id].prev_error = 0;
+				client_requests[req]        .prev_error = 0;
+				break;
+			  }
+			}
+
+			/* Set the flag_tn_error_code and flag_mb_error_code that are mapped onto
+             * located BYTE variables, so the user program
+             * knows how the communication is going.
+             */
+            client_requests[req].flag_mb_error_code = client_requests[req].mb_error_code;
+            client_requests[req].flag_tn_error_code = client_requests[req].tn_error_code;
+            
+            /* We have just finished excuting a client transcation request.
+             * If the current cycle was activated by user request we reset the flag used to ask to run it
+             */
+            if (0 != client_requests[req].flag_exec_req) {
+                client_requests[req].flag_exec_req     = 0;
+                client_requests[req].flag_exec_started = 0;   
+            }
+            
+            //fprintf(stderr, "Modbus plugin: RUNNING<---> of Modbus request %d  (periodic = %d  flag_exec_req = %d)\n", 
+            //        req, client_nodes[client_requests[req].client_node_id].periodic_act, client_requests[req].flag_exec_req );
+        }
+
+        // Wait for signal (from timer or explicit request from user program) before starting the next cycle
+        {
+            // No need to lock the mutex. Is is already locked just before the while(1) loop.
+            // Read the comment there to understand why.
+            // pthread_mutex_lock(&(client_nodes[client_node_id].mutex));
+            
+            /* the client thread has just finished a cycle, so all the flags used to signal an activation
+             * and specify the activation source (periodic, user request, ...)
+             * get reset here, before waiting for a new activation.
+             */
+            client_nodes[client_node_id].periodic_act = 0;            
+            client_nodes[client_node_id].execute_req  = 0;
+            
+            while (client_nodes[client_node_id].execute_req == 0)
+                pthread_cond_wait(&(client_nodes[client_node_id].condv),
+                                &(client_nodes[client_node_id].mutex)); 
+                            
+            // We run the communication cycle with the mutex locked.
+            // Read the comment just above the while(1) to understand why.
+            // pthread_mutex_unlock(&(client_nodes[client_node_id].mutex));
+        }
+	}
+
+	// humour the compiler.
+	return NULL;
+}
+
+
+
+
+
+/* Thread that simply implements a periodic 'timer',
+ *  i.e. periodically sends signal to the  thread running __mb_client_thread()
+ * 
+ * Note that we do not use a posix timer (timer_create() ) because there doesn't seem to be a way
+ * of having the timer notify the thread that is portable across Xenomai and POSIX.
+ * - SIGEV_THREAD    : not supported by Xenomai
+ * - SIGEV_THREAD_ID : Linux specific (i.e. non POSIX)
+ *                     Even so, I did not get it to work under Linux (issues with the header files)
+ * - SIGEV_SIGNAL    : Will not work, as signal is sent to random thread in process!
+ */
+static void *__mb_client_timer_thread(void *_index) {
+	int client_node_id = (char *)_index - (char *)NULL; // Use pointer arithmetic (more portable than cast)
+	struct timespec next_cycle;
+
+	int period_sec  =  client_nodes[client_node_id].comm_period / 1000;          /* comm_period is in ms */
+	int period_nsec = (client_nodes[client_node_id].comm_period %1000)*1000000; /* comm_period is in ms */
+
+	// Enable thread cancelation. Enabled is default, but set it anyway to be safe.
+	pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
+    
+    if (client_nodes[client_node_id].comm_period <= 0) {
+        // No periodic activation required => nothing to do! 
+        while (1) pause(); // wait to be canceled when program terminates (shutdown() is called)
+        return NULL;  // not really necessary, just makes it easier to understand the code.
+    }
+
+	// get the current time
+	clock_gettime(CLOCK_MONOTONIC, &next_cycle);
+
+    while(1) {
+        // Determine absolute time instant for starting the next cycle
+        struct timespec prev_cycle, now;
+        prev_cycle = next_cycle;
+        timespec_add(next_cycle, period_sec, period_nsec);
+                
+        /* NOTE:
+         * It is probably un-necessary to check for overflow of timer!
+         * Even in 32 bit systems this will take at least 68 years since the computer booted
+         * (remember, we are using CLOCK_MONOTONIC, which should start counting from 0
+         * every time the system boots). On 64 bit systems, it will take over 
+         * 10^11 years to overflow.
+         */
+        clock_gettime(CLOCK_MONOTONIC, &now);
+        if (next_cycle.tv_sec < prev_cycle.tv_sec) {
+           /* Timer overflow. See NOTE B above */
+            next_cycle = now;
+            timespec_add(next_cycle, period_sec, period_nsec);
+        }
+        
+        while (0 != clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &next_cycle, NULL));
+        
+        /* signal the client node's condition variable on which the client node's thread should be waiting... */
+        /* Since the communication cycle is run with the mutex locked, we use trylock() instead of lock() */
+        if (pthread_mutex_trylock (&(client_nodes[client_node_id].mutex)) == 0) {
+            client_nodes[client_node_id].execute_req  = 1; // tell the thread to execute
+            client_nodes[client_node_id].periodic_act = 1; // tell the thread the activation was done by periodic timer   
+            pthread_cond_signal (&(client_nodes[client_node_id].condv));
+            pthread_mutex_unlock(&(client_nodes[client_node_id].mutex));
+        } else {
+            /* We never get to signal the thread for activation. But that is OK.
+             * If it still in the communication cycle (during which the mutex is kept locked)
+             * then that means that the communication cycle is falling behing in the periodic 
+             * communication cycle, and we therefore need to skip a period.
+             */
+        }
+    }
+
+    return NULL; // humour the compiler -> will never be executed!
+}
+
+
+int __cleanup_0 ();
+int __init_0 (int argc, char **argv){
+	int index;
+
+	for (index=0; index < NUMBER_OF_CLIENT_NODES;index++) {
+		client_nodes[index].mb_nd = -1;
+        /* see comment in mb_runtime.h to understad why we need to initialize these entries */
+        switch (client_nodes[index].node_address.naf) {
+            case naf_tcp:
+                client_nodes[index].node_address.addr.tcp.host    = client_nodes[index].str1;
+                client_nodes[index].node_address.addr.tcp.service = client_nodes[index].str2;
+                break;
+            case naf_rtu:
+                client_nodes[index].node_address.addr.rtu.device  = client_nodes[index].str1;
+                break;
+        }
+    }
+
+	for (index=0; index < NUMBER_OF_SERVER_NODES;index++) {
+		// mb_nd with negative numbers indicate how far it has been initialised (or not)
+		//   -2  --> no modbus node created;  no thread  created
+		//   -1  -->    modbus node created!; no thread  created
+		//  >=0  -->    modbus node created!;    thread  created!
+		server_nodes[index].mb_nd = -2; 
+		server_nodes[index].mem_area.flag_write_req_flag    = 0; 
+		server_nodes[index].mem_area.flag_write_req_counter = 0; 
+		server_nodes[index].mem_area.flag_read_req_counter  = 0; 
+		server_nodes[index].mem_area.flag_read_req_flag     = 0; 
+        /* see comment in mb_runtime.h to understad why we need to initialize these entries */
+        switch (server_nodes[index].node_address.naf) {
+            case naf_tcp:
+                server_nodes[index].node_address.addr.tcp.host    = server_nodes[index].str1;
+                server_nodes[index].node_address.addr.tcp.service = server_nodes[index].str2;
+                break;
+            case naf_rtu:
+                server_nodes[index].node_address.addr.rtu.device  = server_nodes[index].str1;
+                break;
+        }
+	}
+
+	/* modbus library init */
+	/* Note that TOTAL_xxxNODE_COUNT are the nodes required by _ALL_ the instances of the modbus
+	 *  extension currently in the user's project. This file (MB_xx.c) is handling only one instance,
+	 *  but must initialize the library for all instances. Only the first call to mb_slave_and_master_init()
+	 *  will result in memory being allocated. All subsequent calls (by other MB_xx,c files) will be ignored
+	 *  by the mb_slave_and_master_init() funtion, as long as they are called with the same arguments.
+	 */
+	if (mb_slave_and_master_init(TOTAL_TCPNODE_COUNT, TOTAL_RTUNODE_COUNT, TOTAL_ASCNODE_COUNT) <0) {
+		fprintf(stderr, "Modbus plugin: Error starting modbus library\n");
+		// return imediately. Do NOT goto error_exit, as we did not get to
+		//  start the modbus library!
+		return -1;
+	}
+	
+	/* init each client request */
+	/* Must be done _before_ launching the client threads!! */
+	for (index=0; index < NUMBER_OF_CLIENT_REQTS; index ++){
+        /* make sure flags connected to user program MB transaction start request are all reset */
+        client_requests[index].flag_exec_req     = 0;
+        client_requests[index].flag_exec_started = 0;        
+        /* init the mutex for each client request */
+        /* Must be done _before_ launching the client threads!! */
+		if (pthread_mutex_init(&(client_requests[index].coms_buf_mutex), NULL)) {
+			fprintf(stderr, "Modbus plugin: Error initializing request for modbus client node %s\n", client_nodes[client_requests[index].client_node_id].location);
+			goto error_exit;
+		}
+	}
+
+	/* init each client connection to remote modbus server, and launch thread */
+	/* NOTE: All client_nodes[].init_state are initialised to 0 in the code 
+	 *       generated by the modbus plugin 
+	 */
+	for (index=0; index < NUMBER_OF_CLIENT_NODES;index++){
+		/* establish client connection */
+		client_nodes[index].mb_nd = mb_master_connect (client_nodes[index].node_address);
+		if (client_nodes[index].mb_nd < 0){
+			fprintf(stderr, "Modbus plugin: Error creating modbus client node %s\n", client_nodes[index].location);
+			goto error_exit;
+		}
+		client_nodes[index].init_state = 1; // we have created the node 
+		
+		/* initialize the mutex variable that will be used by the thread handling the client node */
+        bzero(&(client_nodes[index].mutex), sizeof(pthread_mutex_t));
+        if (pthread_mutex_init(&(client_nodes[index].mutex), NULL) < 0) {
+			fprintf(stderr, "Modbus plugin: Error creating mutex for modbus client node %s\n", client_nodes[index].location);
+			goto error_exit;                
+        }
+		client_nodes[index].init_state = 2; // we have created the mutex
+		
+		/* initialize the condition variable that will be used by the thread handling the client node */
+        bzero(&(client_nodes[index].condv), sizeof(pthread_cond_t));
+        if (pthread_cond_init(&(client_nodes[index].condv), NULL) < 0) {
+			fprintf(stderr, "Modbus plugin: Error creating condition variable for modbus client node %s\n", client_nodes[index].location);
+			goto error_exit;                
+        }
+        client_nodes[index].execute_req = 0; //variable associated with condition variable
+		client_nodes[index].init_state = 3; // we have created the condition variable
+		
+		/* launch a thread to handle this client node timer */
+		{
+			int res = 0;
+			pthread_attr_t attr;
+			res |= pthread_attr_init(&attr);
+			res |= pthread_create(&(client_nodes[index].timer_thread_id), &attr, &__mb_client_timer_thread, (void *)((char *)NULL + index));
+			if (res !=  0) {
+				fprintf(stderr, "Modbus plugin: Error starting timer thread for modbus client node %s\n", client_nodes[index].location);
+				goto error_exit;
+			}
+		}
+        client_nodes[index].init_state = 4; // we have created the timer
+
+		/* launch a thread to handle this client node */
+		{
+			int res = 0;
+			pthread_attr_t attr;
+			res |= pthread_attr_init(&attr);
+			res |= pthread_create(&(client_nodes[index].thread_id), &attr, &__mb_client_thread, (void *)((char *)NULL + index));
+			if (res !=  0) {
+				fprintf(stderr, "Modbus plugin: Error starting thread for modbus client node %s\n", client_nodes[index].location);
+				goto error_exit;
+			}
+		}
+		client_nodes[index].init_state = 5; // we have created the thread
+	}
+
+	/* init each local server */
+	/* NOTE: All server_nodes[].init_state are initialised to 0 in the code 
+	 *       generated by the modbus plugin 
+	 */
+	for (index=0; index < NUMBER_OF_SERVER_NODES;index++){
+		/* create the modbus server */
+		server_nodes[index].mb_nd = mb_slave_new (server_nodes[index].node_address);
+		if (server_nodes[index].mb_nd < 0){
+			fprintf(stderr, "Modbus plugin: Error creating modbus server node %s\n", server_nodes[index].location);
+			goto error_exit;
+		}
+		server_nodes[index].init_state = 1; // we have created the node
+		
+		/* launch a thread to handle this server node */
+		{
+			int res = 0;
+			pthread_attr_t attr;
+			res |= pthread_attr_init(&attr);
+			res |= pthread_create(&(server_nodes[index].thread_id), &attr, &__mb_server_thread, (void *)&(server_nodes[index]));
+			if (res !=  0) {
+				fprintf(stderr, "Modbus plugin: Error starting modbus server thread for node %s\n", server_nodes[index].location);
+				goto error_exit;
+			}
+		}
+		server_nodes[index].init_state = 2; // we have created the node and thread
+	}
+
+	return 0;
+	
+error_exit:
+	__cleanup_0 ();
+	return -1;
+}
+
+
+
+
+
+void __publish_0 (){
+	int index;
+
+	for (index=0; index < NUMBER_OF_CLIENT_REQTS; index ++){
+		/* synchronize the PLC and MB buffers only for the output requests */
+		if (client_requests[index].req_type == req_output){
+            
+            // lock the mutex brefore copying the data
+			if(pthread_mutex_trylock(&(client_requests[index].coms_buf_mutex)) == 0){
+                
+                // Check if user configured this MB request to be activated whenever the data to be written changes
+                if (client_requests[index].write_on_change) {
+                    // Let's check if the data did change...
+                    // compare the data in plcv_buffer to coms_buffer
+                    int res;
+                    res = memcmp((void *)client_requests[index].coms_buffer /* buf 1 */,
+                                 (void *)client_requests[index].plcv_buffer /* buf 2*/,
+                                 REQ_BUF_SIZE * sizeof(u16) /* size in bytes */);
+                    
+                    // if data changed, activate execution request 
+                    if (0 != res)
+                        client_requests[index].flag_exec_req = 1;
+                }
+                
+                // copy from plcv_buffer to coms_buffer
+                memcpy((void *)client_requests[index].coms_buffer /* destination */,
+                       (void *)client_requests[index].plcv_buffer /* source */,
+                       REQ_BUF_SIZE * sizeof(u16) /* size in bytes */);
+                pthread_mutex_unlock(&(client_requests[index].coms_buf_mutex));
+            }
+		}
+        /* if the user program set the execution request flag, then activate the thread
+         *  that handles this Modbus client transaction so it gets a chance to be executed
+         *  (but don't activate the thread if it has already been activated!)
+         * 
+         * NOTE that we do this, for both the IN and OUT mapped location, under this
+         *  __publish_() function. The scan cycle of the PLC works as follows:
+         *   - call __retrieve_()
+         *   - execute user programs
+         *   - call __publish_()
+         *   - insert <delay> until time to start next periodic/cyclic scan cycle
+         * 
+         *  In an attempt to be able to run the MB transactions during the <delay>
+         *  interval in which not much is going on, we handle the user program
+         *  requests to execute a specific MB transaction in this __publish_()
+         *  function.
+         */
+        if ((client_requests[index].flag_exec_req != 0) && (0 == client_requests[index].flag_exec_started)) {
+            int client_node_id = client_requests[index].client_node_id;
+            
+             /* We TRY to signal the client thread.
+              * We do this because this function can be called at the end of the PLC scan cycle
+              * and we don't want it to block at that time.
+              */
+             if (pthread_mutex_trylock(&(client_nodes[client_node_id].mutex)) == 0) {
+                 client_nodes[client_node_id].execute_req = 1; // tell the thread to execute
+                 pthread_cond_signal (&(client_nodes[client_node_id].condv));
+                 pthread_mutex_unlock(&(client_nodes[client_node_id].mutex));
+                 /* - upon success, set flag_exec_started
+                  * - both flags (flag_exec_req and flag_exec_started) will be reset
+                  *   once the transaction has completed.
+                  */
+                 client_requests[index].flag_exec_started = 1;    
+             } else {
+                 /* The mutex is locked => the client thread is currently executing MB transactions.
+                  * We will try to activate it in the next PLC cycle...
+                  * For now, do nothing.
+                  */
+             }
+        }                    
+    }
+}
+
+
+
+
+
+void __retrieve_0 (){
+	int index;
+
+	for (index=0; index < NUMBER_OF_CLIENT_REQTS; index ++){
+		/*just do the input requests */
+		if (client_requests[index].req_type == req_input){
+			if(pthread_mutex_trylock(&(client_requests[index].coms_buf_mutex)) == 0){
+                // copy from coms_buffer to plcv_buffer
+                memcpy((void *)client_requests[index].plcv_buffer /* destination */,
+                       (void *)client_requests[index].coms_buffer /* source */,
+                       REQ_BUF_SIZE * sizeof(u16) /* size in bytes */);
+                pthread_mutex_unlock(&(client_requests[index].coms_buf_mutex));
+            }
+		}
+	}
+}
+
+
+
+
+
+int __cleanup_0 (){
+	int index, close;
+	int res = 0;
+
+	/* kill thread and close connections of each modbus client node */
+	for (index=0; index < NUMBER_OF_CLIENT_NODES; index++) {
+		close = 0;
+		if (client_nodes[index].init_state >= 5) {
+			// thread was launched, so we try to cancel it!
+			close  = pthread_cancel(client_nodes[index].thread_id);
+			close |= pthread_join  (client_nodes[index].thread_id, NULL);
+			if (close < 0)
+				fprintf(stderr, "Modbus plugin: Error closing thread for modbus client node %s\n", client_nodes[index].location);
+		}
+		res |= close;
+
+		close = 0;
+		if (client_nodes[index].init_state >= 4) {
+			// timer thread was launched, so we try to cancel it!
+			close  = pthread_cancel(client_nodes[index].timer_thread_id);
+			close |= pthread_join  (client_nodes[index].timer_thread_id, NULL);
+			if (close < 0)
+				fprintf(stderr, "Modbus plugin: Error closing timer thread for modbus client node %s\n", client_nodes[index].location);
+
+		}
+		res |= close;
+
+		close = 0;
+		if (client_nodes[index].init_state >= 3) {
+			// condition variable was created, so we try to destroy it!
+			close  = pthread_cond_destroy(&(client_nodes[index].condv));
+			if (close < 0)
+				fprintf(stderr, "Modbus plugin: Error destroying condition variable for modbus client node %s\n", client_nodes[index].location);
+		}
+		res |= close;
+
+		close = 0;
+		if (client_nodes[index].init_state >= 2) {
+			// mutex was created, so we try to destroy it!
+			close  = pthread_mutex_destroy(&(client_nodes[index].mutex));
+			if (close < 0)
+				fprintf(stderr, "Modbus plugin: Error destroying mutex for modbus client node %s\n", client_nodes[index].location);
+		}
+		res |= close;
+
+		close = 0;
+		if (client_nodes[index].init_state >= 1) {
+			// modbus client node was created, so we try to close it!
+			close = mb_master_close (client_nodes[index].mb_nd);
+			if (close < 0){
+				fprintf(stderr, "Modbus plugin: Error closing modbus client node %s\n", client_nodes[index].location);
+				// We try to shut down as much as possible, so we do not return noW!
+			}
+			client_nodes[index].mb_nd = -1;
+		}
+		res |= close;
+		client_nodes[index].init_state = 0;
+	}
+	
+//fprintf(stderr, "Modbus plugin: __cleanup_%s()  5  close=%d   res=%d\n", client_nodes[index].location, close, res);
+	/* kill thread and close connections of each modbus server node */
+	for (index=0; index < NUMBER_OF_SERVER_NODES; index++) {
+		close = 0;
+		if (server_nodes[index].init_state >= 2) {
+			// thread was launched, so we try to cancel it!
+			close  = pthread_cancel(server_nodes[index].thread_id);
+			close |= pthread_join  (server_nodes[index].thread_id, NULL);
+			if (close < 0)
+				fprintf(stderr, "Modbus plugin: Error closing thread for modbus server %s\n", server_nodes[index].location);
+		}
+		res |= close;
+
+		close = 0;
+		if (server_nodes[index].init_state >= 1) {
+			// modbus server node was created, so we try to close it!
+			close = mb_slave_close (server_nodes[index].mb_nd);
+			if (close < 0) {
+				fprintf(stderr, "Modbus plugin: Error closing node for modbus server %s (%d)\n", server_nodes[index].location, server_nodes[index].mb_nd);
+				// We try to shut down as much as possible, so we do not return noW!
+			}
+			server_nodes[index].mb_nd = -1;
+		}
+		res |= close;
+		server_nodes[index].init_state = 0;
+	}
+
+	/* destroy the mutex of each client request */
+	for (index=0; index < NUMBER_OF_CLIENT_REQTS; index ++) {
+		if (pthread_mutex_destroy(&(client_requests[index].coms_buf_mutex))) {
+			fprintf(stderr, "Modbus plugin: Error destroying request for modbus client node %s\n", client_nodes[client_requests[index].client_node_id].location);
+			// We try to shut down as much as possible, so we do not return noW!
+			res |= -1;
+		}
+	}
+
+	/* modbus library close */
+	//fprintf(stderr, "Shutting down modbus library...\n");
+	if (mb_slave_and_master_done()<0) {
+		fprintf(stderr, "Modbus plugin: Error shutting down modbus library\n");
+		res |= -1;
+	}
+
+	return res;
+}
+
+
+
+
+
+/**********************************************/
+/** Functions for Beremiz web interface.     **/
+/**********************************************/
+
+/*
+ * Beremiz has a program to run on the PLC (Beremiz_service.py)
+ * to handle downloading of compiled programs, start/stop of PLC, etc.
+ * (see runtime/PLCObject.py for start/stop, loading, ...)
+ * 
+ * This service also includes a web server to access PLC state (start/stop)
+ * and to change some basic confiuration parameters.
+ * (see runtime/NevowServer.py for the web server)
+ * 
+ * The web server allows for extensions, where additional configuration
+ * parameters may be changed on the running/downloaded PLC.
+ * Modbus plugin also comes with an extension to the web server, through
+ * which the basic Modbus plugin configuration parameters may be changed
+ * 
+ * These parameters are changed _after_ the code (.so file) is loaded into 
+ * memmory. These changes may be applied before (or after) the code starts
+ * running (i.e. before or after __init_() ets called)! 
+ * 
+ * The following functions are never called from other C code. They are 
+ * called instead from the python code in runtime/Modbus_config.py, that
+ * implements the web server extension for configuring Modbus parameters.
+ */
+
+
+/* The number of Cient nodes (i.e. the number of entries in the client_nodes array)
+ * The number of Server nodes (i.e. the numb. of entries in the server_nodes array)
+ * 
+ * These variables are also used by the Modbus web config code to determine 
+ * whether the current loaded PLC includes the Modbus plugin
+ * (so it should make the Modbus parameter web interface visible to the user).
+ */
+const int __modbus_plugin_client_node_count = NUMBER_OF_CLIENT_NODES;
+const int __modbus_plugin_server_node_count = NUMBER_OF_SERVER_NODES;
+const int __modbus_plugin_param_string_size = MODBUS_PARAM_STRING_SIZE;
+
+
+
+/* NOTE: We could have the python code in runtime/Modbus_config.py
+ *       directly access the server_node_t and client_node_t structures,
+ *       however this would create a tight coupling between these two
+ *       disjoint pieces of code.
+ *       Any change to the server_node_t or client_node_t structures would
+ *       require the python code to be changed accordingly. I have therefore 
+ *       opted to create get/set functions, one for each parameter.
+ * 
+ *       We also convert the enumerated constants naf_ascii, etc...
+ *       (from node_addr_family_t in modbus/mb_addr.h)
+ *       into strings so as to decouple the python code that will be calling
+ *       these functions from the Modbus library code definitions.
+ */
+const char *addr_type_str[] = {
+        [naf_ascii] = "ascii",
+        [naf_rtu  ] = "rtu",
+        [naf_tcp  ] = "tcp"    
+};
+
+
+#define __safe_strcnpy(str_dest, str_orig, max_size) {  \
+    strncpy(str_dest, str_orig, max_size);              \
+    str_dest[max_size - 1] = '\0';                      \
+}
+
+
+/* NOTE: The host, port and device parameters are strings that may be changed 
+ *       (by calling the following functions) after loading the compiled code 
+ *       (.so file) into memory, but before the code starts running
+ *       (i.e. before __init_() gets called).
+ *       This means that the host, port and device parameters may be changed
+ *       _before_ they get mapped onto the str1 and str2 variables by __init_(),
+ *       which is why the following functions must access the str1 and str2 
+ *       parameters directly.
+ */
+const char *       __modbus_get_ClientNode_config_name(int nodeid)  {return client_nodes[nodeid].config_name;                    }
+const char *       __modbus_get_ClientNode_host       (int nodeid)  {return client_nodes[nodeid].str1;                           }
+const char *       __modbus_get_ClientNode_port       (int nodeid)  {return client_nodes[nodeid].str2;                           }
+const char *       __modbus_get_ClientNode_device     (int nodeid)  {return client_nodes[nodeid].str1;                           }
+int                __modbus_get_ClientNode_baud       (int nodeid)  {return client_nodes[nodeid].node_address.addr.rtu.baud;     }
+int                __modbus_get_ClientNode_parity     (int nodeid)  {return client_nodes[nodeid].node_address.addr.rtu.parity;   }
+int                __modbus_get_ClientNode_stop_bits  (int nodeid)  {return client_nodes[nodeid].node_address.addr.rtu.stop_bits;}
+u64                __modbus_get_ClientNode_comm_period(int nodeid)  {return client_nodes[nodeid].comm_period;                    }
+const char *       __modbus_get_ClientNode_addr_type  (int nodeid)  {return addr_type_str[client_nodes[nodeid].node_address.naf];}
+                                                                                                                        
+const char *       __modbus_get_ServerNode_config_name(int nodeid)  {return server_nodes[nodeid].config_name;                    }
+const char *       __modbus_get_ServerNode_host       (int nodeid)  {char*x=server_nodes[nodeid].str1; return (x[0]=='\0'?"#ANY#":x); }
+const char *       __modbus_get_ServerNode_port       (int nodeid)  {return server_nodes[nodeid].str2;                           }
+const char *       __modbus_get_ServerNode_device     (int nodeid)  {return server_nodes[nodeid].str1;                           }
+int                __modbus_get_ServerNode_baud       (int nodeid)  {return server_nodes[nodeid].node_address.addr.rtu.baud;     }
+int                __modbus_get_ServerNode_parity     (int nodeid)  {return server_nodes[nodeid].node_address.addr.rtu.parity;   }
+int                __modbus_get_ServerNode_stop_bits  (int nodeid)  {return server_nodes[nodeid].node_address.addr.rtu.stop_bits;}
+u8                 __modbus_get_ServerNode_slave_id   (int nodeid)  {return server_nodes[nodeid].slave_id;                       }
+const char *       __modbus_get_ServerNode_addr_type  (int nodeid)  {return addr_type_str[server_nodes[nodeid].node_address.naf];}
+
+
+void __modbus_set_ClientNode_host       (int nodeid, const char * value)  {__safe_strcnpy(client_nodes[nodeid].str1, value, MODBUS_PARAM_STRING_SIZE);}
+void __modbus_set_ClientNode_port       (int nodeid, const char * value)  {__safe_strcnpy(client_nodes[nodeid].str2, value, MODBUS_PARAM_STRING_SIZE);}
+void __modbus_set_ClientNode_device     (int nodeid, const char * value)  {__safe_strcnpy(client_nodes[nodeid].str1, value, MODBUS_PARAM_STRING_SIZE);}
+void __modbus_set_ClientNode_baud       (int nodeid, int          value)  {client_nodes[nodeid].node_address.addr.rtu.baud      = value;}
+void __modbus_set_ClientNode_parity     (int nodeid, int          value)  {client_nodes[nodeid].node_address.addr.rtu.parity    = value;}
+void __modbus_set_ClientNode_stop_bits  (int nodeid, int          value)  {client_nodes[nodeid].node_address.addr.rtu.stop_bits = value;}
+void __modbus_set_ClientNode_comm_period(int nodeid, u64          value)  {client_nodes[nodeid].comm_period                     = value;}
+                                                                                                                        
+
+void __modbus_set_ServerNode_host       (int nodeid, const char * value)  {if (strcmp(value,"#ANY#")==0) value = "";
+                                                                           __safe_strcnpy(server_nodes[nodeid].str1, value, MODBUS_PARAM_STRING_SIZE);}
+void __modbus_set_ServerNode_port       (int nodeid, const char * value)  {__safe_strcnpy(server_nodes[nodeid].str2, value, MODBUS_PARAM_STRING_SIZE);}
+void __modbus_set_ServerNode_device     (int nodeid, const char * value)  {__safe_strcnpy(server_nodes[nodeid].str1, value, MODBUS_PARAM_STRING_SIZE);}
+void __modbus_set_ServerNode_baud       (int nodeid, int          value)  {server_nodes[nodeid].node_address.addr.rtu.baud      = value;}
+void __modbus_set_ServerNode_parity     (int nodeid, int          value)  {server_nodes[nodeid].node_address.addr.rtu.parity    = value;}
+void __modbus_set_ServerNode_stop_bits  (int nodeid, int          value)  {server_nodes[nodeid].node_address.addr.rtu.stop_bits = value;}
+void __modbus_set_ServerNode_slave_id   (int nodeid, u8           value)  {server_nodes[nodeid].slave_id                        = value;}
+

Beremiz/beremiz_tutorial_opc_ua/build/MB_0.h

+/* File generated by Beremiz (PlugGenerate_C method of modbus Plugin instance) */
+
+/*
+ * Copyright (c) 2016 Mario de Sousa (msousa@fe.up.pt)
+ *
+ * This file is part of the Modbus library for Beremiz and matiec.
+ *
+ * This Modbus library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser 
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this Modbus library.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * This code is made available on the understanding that it will not be
+ * used in safety-critical situations without a full and competent review.
+ */
+
+#include "mb_addr.h"
+#include "mb_tcp_private.h"
+#include "mb_master_private.h"
+
+
+
+#define DEF_REQ_SEND_RETRIES 0
+
+
+#define MODBUS_PARAM_STRING_SIZE 64
+
+
+  // Used by the Modbus server node
+#define MEM_AREA_SIZE 65536
+typedef struct{
+	    u16		ro_bits [MEM_AREA_SIZE];
+	    u16		rw_bits [MEM_AREA_SIZE];
+	    u16		ro_words[MEM_AREA_SIZE];
+	    u16		rw_words[MEM_AREA_SIZE];
+            /* Two flags to count the number of Modbus requests (read and write) we have 
+             * successfully received from any remote Modbus master.
+             * Two boolean flags that are set whenever we successfully process a
+             * Modbus request sent from a remote client.
+             * These flags will be mapped onto located variables
+             * so the user's IEC 61131-3 code can check whether we are being
+             * polled by a Modbus master.
+             * The counters will roll over to 0 upon reaching maximum value.
+             * The user will probably periodically reset the boolean flags to false,
+             * and use this as a communication timeout 
+             * (when it remains false in two consecutive periods)
+             * 
+             * u8  for BOOL  variable/flag
+             * u32 for UDINT variable/counter
+             */
+        u8   flag_write_req_flag;
+        u8   flag_read_req_flag;
+        u32  flag_write_req_counter;
+        u32  flag_read_req_counter;
+	} server_mem_t;
+
+
+/*
+ * Beremiz has a program to run on the PLC (Beremiz_service.py)
+ * to handle downloading of compiled programs, start/stop of PLC, etc.
+ * (see runtime/PLCObject.py for start/stop, loading, ...)
+ * 
+ * This service also includes a web server to access PLC state (start/stop)
+ * and to change some basic confiuration parameters.
+ * (see runtime/NevowServer.py for the web server)
+ * 
+ * The web server allows for extensions, where additional configuration
+ * parameters may be changed on the running/downloaded PLC.
+ * Modbus plugin also comes with an extension to the web server, through
+ * which the basic Modbus plugin configuration parameters may be changed
+ *
+ * This means that most values in the server_node_t and client_node_t
+ * may be changed after the co,piled code (.so file) is loaded into 
+ * memory, and before the code starts executing.
+ * Since the we will also want to change the host and port (TCP) and the
+ * serial device (RTU) at this time, it is best if we allocate memory for
+ * these strings that may be overwritten by the web server (i.e., do not use
+ * const strings) in the server_node_t and client_node_t structures.
+ *
+ * The following structure members
+ *    - node_addr_t.addr.tcp.host
+ *    - node_addr_t.addr.tcp.service  (i.e. the port)
+ *    - node_addr_t.addr.rtu.device
+ * are all char *, and do not allocate memory for the strings.
+ * 
+ * We therefore include two generic char arrays, str1 and str2,
+ * that will store the above strings, and the C code will initiliaze
+ * the node_addre_t.addr string pointers to these strings.
+ * i.e., either addr.rtu.device will point to str1,
+ *          or
+ *        addr.tcp.host and addr.tcp.service 
+ *        will point to str1 and str2 respectively
+ */
+typedef struct{
+	    const char *location;
+        const char *config_name;
+              char  str1[MODBUS_PARAM_STRING_SIZE];
+              char  str2[MODBUS_PARAM_STRING_SIZE]; 
+	    u8		slave_id;
+	    node_addr_t	node_address;
+	    int		mb_nd;      // modbus library node used for this server 
+	    int		init_state; // store how far along the server's initialization has progressed
+            /* entries from this point forward are not statically initialized when the variable is declared */
+            /* they will be initialized by the  code itself in the init() function */
+	    pthread_t	thread_id;  // thread handling this server
+	    server_mem_t	mem_area;
+	} server_node_t;
+
+
+  // Used by the Modbus client node
+typedef struct{
+	    const char *location;
+        const char *config_name;
+              char  str1[MODBUS_PARAM_STRING_SIZE];
+              char  str2[MODBUS_PARAM_STRING_SIZE]; 
+	    node_addr_t	node_address;
+	    int		mb_nd;      // modbus library node used for this client
+	    int		init_state; // store how far along the client's initialization has progressed
+	    u64		comm_period;// period to use when periodically sending requests to remote server
+	    int		prev_error; // error code of the last printed error message (0 when no error) 
+	    pthread_t   thread_id;  // thread handling all communication for this client node
+	    pthread_t	timer_thread_id;  // thread handling periodical timer for this client node
+	    pthread_mutex_t mutex;  // mutex to be used with the following condition variable
+        pthread_cond_t  condv;  // used to signal the client thread when to start new modbus transactions
+        int       execute_req;  /* used, in association with condition variable,  
+                                 *   to signal when to send the modbus request to the server
+                                 * Note that we cannot simply rely on the condition variable to signal
+                                 *   when to activate the client thread, as the call to 
+                                 *   pthread_cond_wait() may return without having been signaled!
+                                 *   From the manual:
+                                 *      Spurious  wakeups  from  the
+                                 *      pthread_cond_timedwait() or pthread_cond_wait()  functions  may  occur.
+                                 *      Since  the  return from pthread_cond_timedwait() or pthread_cond_wait()
+                                 *      does not imply anything about the value of this predicate,  the  predi-
+                                 *      cate should be re-evaluated upon such return.
+                                 */
+        int      periodic_act;  /* (boolen) flag will be set when the client node's thread was activated 
+                                 * (by signaling the above condition variable) by the periodic timer.
+                                 * Note that this same thread may also be activated (condition variable is signaled)
+                                 * by other sources, such as when the user program requests that a specific 
+                                 * client MB transation be executed (flag_exec_req in client_request_t)
+                                 */
+	} client_node_t;
+
+
+  // Used by the Modbus client plugin
+typedef enum {
+	    req_input,
+	    req_output,
+	    no_request		/* just for tests to quickly disable a request */
+	} iotype_t;
+
+#define REQ_BUF_SIZE 2000
+typedef struct{
+	    const char *location;
+	    int		client_node_id;
+	    u8		slave_id;
+	    iotype_t	req_type;
+	    u8		mb_function;
+	    u16		address;
+	    u16		count;
+	    int		retries;
+	    u8		mb_error_code; // modbus      error code (if any) of last executed request
+	    u8		tn_error_code; // transaction error code (if any) of last executed request
+	    int		prev_error; // error code of the last printed error message (0 when no error) 
+	    struct timespec resp_timeout;
+	    u8		write_on_change; // boolean flag. If true => execute MB request when data to send changes
+	      // buffer used to store located PLC variables
+	    u16		plcv_buffer[REQ_BUF_SIZE];
+	      // buffer used to store data coming from / going to server
+	    u16		coms_buffer[REQ_BUF_SIZE]; 
+	    pthread_mutex_t coms_buf_mutex; // mutex to access coms_buffer[]
+          /* boolean flag that will be mapped onto a (BOOL) located variable 
+           * (u8 because IEC 61131-3 BOOL are mapped onto u8 in C code! )
+           *    -> allow PLC program to request when to start the MB transaction
+           *    -> will be reset once the MB transaction has completed
+           */
+        u8     flag_exec_req;  
+          /* flag that works in conjunction with flag_exec_req
+           * (does not really need to be u8 as it is not mapped onto a located variable. )
+           *    -> used by internal logic to indicate that the client thread 
+           *       that will be executing the MB transaction
+           *       requested by flag exec_req has already been activated.
+           *    -> will be reset once the MB transaction has completed
+           */
+        u8     flag_exec_started;  
+          /* flag that will be mapped onto a (BYTE) located variable 
+           * (u8 because the flag is a BYTE! )
+           *    -> will store the result of the last executed MB transaction
+           *         1 -> error accessing IP network, or serial interface
+           *         2 -> reply received from server was an invalid frame
+           *         3 -> server did not reply before timeout expired
+           *         4 -> server returned a valid Modbus error frame
+           *    -> will be reset (set to 0) once this MB transaction has completed sucesfully
+           * 
+           * In other words, this variable is a copy of tn_error_code, reset after each request attempt completes.
+           * We map this copy (instead of tn_error_code) onto a located variable in case the user program decides
+           * to overwrite its value and mess up the plugin logic.
+           */
+        u8      flag_tn_error_code;  
+          /* flag that will be mapped onto a (BYTE) located variable 
+           * (u8 because the flag is a BYTE! )
+           *    -> if flag_tn_error_code is 4, this flag will store the MB error code returned by the MB server in a MB error frame
+           *    -> will be reset (set to 0) once this MB transaction has completed succesfully
+           * 
+           * In other words, this variable is a copy of mb_error_code, reset after each request attempt completes.
+           * We map this copy (instead of mb_error_code) onto a located variable in case the user program decides
+           * to overwrite its value and mess up the plugin logic.
+           */
+        u8      flag_mb_error_code;  
+	} client_request_t;
+
+
+/* The total number of nodes, needed to support _all_ instances of the modbus plugin */
+#define TOTAL_TCPNODE_COUNT       11
+#define TOTAL_RTUNODE_COUNT       0
+#define TOTAL_ASCNODE_COUNT       0
+
+/* Values for instance 0 of the modbus plugin */
+#define MAX_NUMBER_OF_TCPCLIENTS  10
+
+#define NUMBER_OF_TCPSERVER_NODES 0
+#define NUMBER_OF_TCPCLIENT_NODES 1
+#define NUMBER_OF_TCPCLIENT_REQTS 4
+
+#define NUMBER_OF_RTUSERVER_NODES 0
+#define NUMBER_OF_RTUCLIENT_NODES 0
+#define NUMBER_OF_RTUCLIENT_REQTS 0
+
+#define NUMBER_OF_ASCIISERVER_NODES 0
+#define NUMBER_OF_ASCIICLIENT_NODES 0
+#define NUMBER_OF_ASCIICLIENT_REQTS 0
+
+#define NUMBER_OF_SERVER_NODES (NUMBER_OF_TCPSERVER_NODES + \
+                                NUMBER_OF_RTUSERVER_NODES + \
+                                NUMBER_OF_ASCIISERVER_NODES)
+
+#define NUMBER_OF_CLIENT_NODES (NUMBER_OF_TCPCLIENT_NODES + \
+                                NUMBER_OF_RTUCLIENT_NODES + \
+                                NUMBER_OF_ASCIICLIENT_NODES)
+
+#define NUMBER_OF_CLIENT_REQTS (NUMBER_OF_TCPCLIENT_REQTS + \
+                                NUMBER_OF_RTUCLIENT_REQTS + \
+                                NUMBER_OF_ASCIICLIENT_REQTS)
+
+
+/*initialization following all parameters given by user in application*/
+
+static client_node_t		client_nodes[NUMBER_OF_CLIENT_NODES] = {
+/*node 0.0*/
+{"0.0", "Modbus TCP Client 0.0", "192.168.0.78", "1502", {naf_tcp, {.tcp = {NULL, NULL, DEF_CLOSE_ON_SILENCE}}}, -1 /* mb_nd */, 0 /* init_state */, 1000 /* communication period */, 0 /* prev_error */}
+};
+
+
+static client_request_t	client_requests[NUMBER_OF_CLIENT_REQTS] = {
+/*request 0_0_0*/
+{"0_0_0", 0, 0, req_output, 5, 0 , 1,
+DEF_REQ_SEND_RETRIES, 0 /* mb_error_code */, 0 /* tn_error_code */, 0 /* prev_code */, {0, 30000000} /* timeout */, 0 /* write_on_change */, 
+{0}, {0}},
+
+/*request 0_0_1*/
+{"0_0_1", 0, 0, req_output, 5, 1 , 1,
+DEF_REQ_SEND_RETRIES, 0 /* mb_error_code */, 0 /* tn_error_code */, 0 /* prev_code */, {0, 30000000} /* timeout */, 0 /* write_on_change */, 
+{0}, {0}},
+
+/*request 0_0_2*/
+{"0_0_2", 0, 0, req_output, 5, 2 , 1,
+DEF_REQ_SEND_RETRIES, 0 /* mb_error_code */, 0 /* tn_error_code */, 0 /* prev_code */, {0, 30000000} /* timeout */, 0 /* write_on_change */, 
+{0}, {0}},
+
+/*request 0_0_3*/
+{"0_0_3", 0, 0, req_output, 5, 3 , 1,
+DEF_REQ_SEND_RETRIES, 0 /* mb_error_code */, 0 /* tn_error_code */, 0 /* prev_code */, {0, 30000000} /* timeout */, 0 /* write_on_change */, 
+{0}, {0}}
+};
+
+
+static server_node_t		server_nodes[NUMBER_OF_SERVER_NODES] = {
+
+}
+;
+
+/*******************/
+/*located variables*/
+/*******************/
+
+u16 *__QX0_0_0_0 = &client_requests[0].plcv_buffer[0];
+u16 *__QX0_0_1_1 = &client_requests[1].plcv_buffer[0];
+u16 *__QX0_0_2_2 = &client_requests[2].plcv_buffer[0];
+u16 *__QX0_0_3_3 = &client_requests[3].plcv_buffer[0];
+

Beremiz/beremiz_tutorial_opc_ua/build/POUS.c

+void LOGGER_init__(LOGGER *data__, BOOL retain) {
+  __INIT_VAR(data__->EN,__BOOL_LITERAL(TRUE),retain)
+  __INIT_VAR(data__->ENO,__BOOL_LITERAL(TRUE),retain)
+  __INIT_VAR(data__->TRIG,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->MSG,__STRING_LITERAL(0,""),retain)
+  __INIT_VAR(data__->LEVEL,LOGLEVEL__INFO,retain)
+  __INIT_VAR(data__->TRIG0,__BOOL_LITERAL(FALSE),retain)
+}
+
+// Code part
+void LOGGER_body__(LOGGER *data__) {
+  // Control execution
+  if (!__GET_VAR(data__->EN)) {
+    __SET_VAR(data__->,ENO,,__BOOL_LITERAL(FALSE));
+    return;
+  }
+  else {
+    __SET_VAR(data__->,ENO,,__BOOL_LITERAL(TRUE));
+  }
+  // Initialise TEMP variables
+
+  if ((__GET_VAR(data__->TRIG,) && !(__GET_VAR(data__->TRIG0,)))) {
+    #define GetFbVar(var,...) __GET_VAR(data__->var,__VA_ARGS__)
+    #define SetFbVar(var,val,...) __SET_VAR(data__->,var,__VA_ARGS__,val)
+
+   LogMessage(GetFbVar(LEVEL),(char*)GetFbVar(MSG, .body),GetFbVar(MSG, .len));
+  
+    #undef GetFbVar
+    #undef SetFbVar
+;
+  };
+  __SET_VAR(data__->,TRIG0,,__GET_VAR(data__->TRIG,));
+
+  goto __end;
+
+__end:
+  return;
+} // LOGGER_body__() 
+
+
+
+
+
+void PYTHON_EVAL_init__(PYTHON_EVAL *data__, BOOL retain) {
+  __INIT_VAR(data__->EN,__BOOL_LITERAL(TRUE),retain)
+  __INIT_VAR(data__->ENO,__BOOL_LITERAL(TRUE),retain)
+  __INIT_VAR(data__->TRIG,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->CODE,__STRING_LITERAL(0,""),retain)
+  __INIT_VAR(data__->ACK,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->RESULT,__STRING_LITERAL(0,""),retain)
+  __INIT_VAR(data__->STATE,0,retain)
+  __INIT_VAR(data__->BUFFER,__STRING_LITERAL(0,""),retain)
+  __INIT_VAR(data__->PREBUFFER,__STRING_LITERAL(0,""),retain)
+  __INIT_VAR(data__->TRIGM1,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->TRIGGED,__BOOL_LITERAL(FALSE),retain)
+}
+
+// Code part
+void PYTHON_EVAL_body__(PYTHON_EVAL *data__) {
+  // Control execution
+  if (!__GET_VAR(data__->EN)) {
+    __SET_VAR(data__->,ENO,,__BOOL_LITERAL(FALSE));
+    return;
+  }
+  else {
+    __SET_VAR(data__->,ENO,,__BOOL_LITERAL(TRUE));
+  }
+  // Initialise TEMP variables
+
+  __IL_DEFVAR_T __IL_DEFVAR;
+  __IL_DEFVAR_T __IL_DEFVAR_BACK;
+  #define GetFbVar(var,...) __GET_VAR(data__->var,__VA_ARGS__)
+  #define SetFbVar(var,val,...) __SET_VAR(data__->,var,__VA_ARGS__,val)
+extern void __PythonEvalFB(int, PYTHON_EVAL*);__PythonEvalFB(0, data__);
+  #undef GetFbVar
+  #undef SetFbVar
+;
+
+  goto __end;
+
+__end:
+  return;
+} // PYTHON_EVAL_body__() 
+
+
+
+
+
+void PYTHON_POLL_init__(PYTHON_POLL *data__, BOOL retain) {
+  __INIT_VAR(data__->EN,__BOOL_LITERAL(TRUE),retain)
+  __INIT_VAR(data__->ENO,__BOOL_LITERAL(TRUE),retain)
+  __INIT_VAR(data__->TRIG,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->CODE,__STRING_LITERAL(0,""),retain)
+  __INIT_VAR(data__->ACK,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->RESULT,__STRING_LITERAL(0,""),retain)
+  __INIT_VAR(data__->STATE,0,retain)
+  __INIT_VAR(data__->BUFFER,__STRING_LITERAL(0,""),retain)
+  __INIT_VAR(data__->PREBUFFER,__STRING_LITERAL(0,""),retain)
+  __INIT_VAR(data__->TRIGM1,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->TRIGGED,__BOOL_LITERAL(FALSE),retain)
+}
+
+// Code part
+void PYTHON_POLL_body__(PYTHON_POLL *data__) {
+  // Control execution
+  if (!__GET_VAR(data__->EN)) {
+    __SET_VAR(data__->,ENO,,__BOOL_LITERAL(FALSE));
+    return;
+  }
+  else {
+    __SET_VAR(data__->,ENO,,__BOOL_LITERAL(TRUE));
+  }
+  // Initialise TEMP variables
+
+  __IL_DEFVAR_T __IL_DEFVAR;
+  __IL_DEFVAR_T __IL_DEFVAR_BACK;
+  #define GetFbVar(var,...) __GET_VAR(data__->var,__VA_ARGS__)
+  #define SetFbVar(var,val,...) __SET_VAR(data__->,var,__VA_ARGS__,val)
+extern void __PythonEvalFB(int, PYTHON_EVAL*);__PythonEvalFB(1,(PYTHON_EVAL*)(void*)data__);
+  #undef GetFbVar
+  #undef SetFbVar
+;
+
+  goto __end;
+
+__end:
+  return;
+} // PYTHON_POLL_body__() 
+
+
+
+
+
+void PYTHON_GEAR_init__(PYTHON_GEAR *data__, BOOL retain) {
+  __INIT_VAR(data__->EN,__BOOL_LITERAL(TRUE),retain)
+  __INIT_VAR(data__->ENO,__BOOL_LITERAL(TRUE),retain)
+  __INIT_VAR(data__->N,0,retain)
+  __INIT_VAR(data__->TRIG,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->CODE,__STRING_LITERAL(0,""),retain)
+  __INIT_VAR(data__->ACK,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->RESULT,__STRING_LITERAL(0,""),retain)
+  PYTHON_EVAL_init__(&data__->PY_EVAL,retain);
+  __INIT_VAR(data__->COUNTER,0,retain)
+  __INIT_VAR(data__->_TMP_ADD10_OUT,0,retain)
+  __INIT_VAR(data__->_TMP_EQ13_OUT,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->_TMP_SEL15_OUT,0,retain)
+  __INIT_VAR(data__->_TMP_AND7_OUT,__BOOL_LITERAL(FALSE),retain)
+}
+
+// Code part
+void PYTHON_GEAR_body__(PYTHON_GEAR *data__) {
+  // Control execution
+  if (!__GET_VAR(data__->EN)) {
+    __SET_VAR(data__->,ENO,,__BOOL_LITERAL(FALSE));
+    return;
+  }
+  else {
+    __SET_VAR(data__->,ENO,,__BOOL_LITERAL(TRUE));
+  }
+  // Initialise TEMP variables
+
+  __SET_VAR(data__->,_TMP_ADD10_OUT,,ADD__UINT__UINT(
+    (BOOL)__BOOL_LITERAL(TRUE),
+    NULL,
+    (UINT)2,
+    (UINT)__GET_VAR(data__->COUNTER,),
+    (UINT)1));
+  __SET_VAR(data__->,_TMP_EQ13_OUT,,EQ__BOOL__UINT(
+    (BOOL)__BOOL_LITERAL(TRUE),
+    NULL,
+    (UINT)2,
+    (UINT)__GET_VAR(data__->N,),
+    (UINT)__GET_VAR(data__->_TMP_ADD10_OUT,)));
+  __SET_VAR(data__->,_TMP_SEL15_OUT,,SEL__UINT__BOOL__UINT__UINT(
+    (BOOL)__BOOL_LITERAL(TRUE),
+    NULL,
+    (BOOL)__GET_VAR(data__->_TMP_EQ13_OUT,),
+    (UINT)__GET_VAR(data__->_TMP_ADD10_OUT,),
+    (UINT)0));
+  __SET_VAR(data__->,COUNTER,,__GET_VAR(data__->_TMP_SEL15_OUT,));
+  __SET_VAR(data__->,_TMP_AND7_OUT,,AND__BOOL__BOOL(
+    (BOOL)__BOOL_LITERAL(TRUE),
+    NULL,
+    (UINT)2,
+    (BOOL)__GET_VAR(data__->_TMP_EQ13_OUT,),
+    (BOOL)__GET_VAR(data__->TRIG,)));
+  __SET_VAR(data__->PY_EVAL.,TRIG,,__GET_VAR(data__->_TMP_AND7_OUT,));
+  __SET_VAR(data__->PY_EVAL.,CODE,,__GET_VAR(data__->CODE,));
+  PYTHON_EVAL_body__(&data__->PY_EVAL);
+  __SET_VAR(data__->,ACK,,__GET_VAR(data__->PY_EVAL.ACK,));
+  __SET_VAR(data__->,RESULT,,__GET_VAR(data__->PY_EVAL.RESULT,));
+
+  goto __end;
+
+__end:
+  return;
+} // PYTHON_GEAR_body__() 
+
+
+
+
+
+void COUNTERST_init__(COUNTERST *data__, BOOL retain) {
+  __INIT_VAR(data__->EN,__BOOL_LITERAL(TRUE),retain)
+  __INIT_VAR(data__->ENO,__BOOL_LITERAL(TRUE),retain)
+  __INIT_VAR(data__->RESET,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->OUT1,0,retain)
+  __INIT_VAR(data__->OUT0,0,retain)
+  __INIT_VAR(data__->CNT1,0,retain)
+  __INIT_VAR(data__->CNT0,0,retain)
+  __INIT_EXTERNAL(INT,RESETCOUNTERVALUE,data__->RESETCOUNTERVALUE,retain)
+  __INIT_EXTERNAL(BOOL,RELAY0VALUE,data__->RELAY0VALUE,retain)
+  __INIT_EXTERNAL(BOOL,RELAY1VALUE,data__->RELAY1VALUE,retain)
+  __INIT_EXTERNAL(BOOL,RELAY2VALUE,data__->RELAY2VALUE,retain)
+  __INIT_EXTERNAL(BOOL,RELAY3VALUE,data__->RELAY3VALUE,retain)
+  __INIT_EXTERNAL(DINT,RELAY3VALUE0,data__->RELAY3VALUE0,retain)
+}
+
+// Code part
+void COUNTERST_body__(COUNTERST *data__) {
+  // Control execution
+  if (!__GET_VAR(data__->EN)) {
+    __SET_VAR(data__->,ENO,,__BOOL_LITERAL(FALSE));
+    return;
+  }
+  else {
+    __SET_VAR(data__->,ENO,,__BOOL_LITERAL(TRUE));
+  }
+  // Initialise TEMP variables
+
+  if (__GET_VAR(data__->RESET,)) {
+    __SET_VAR(data__->,CNT0,,__GET_EXTERNAL(data__->RESETCOUNTERVALUE,));
+    __SET_VAR(data__->,CNT1,,__GET_EXTERNAL(data__->RESETCOUNTERVALUE,));
+    __SET_VAR(data__->,RESET,,__BOOL_LITERAL(FALSE));
+  } else {
+    __SET_VAR(data__->,CNT0,,(__GET_VAR(data__->CNT0,) + 1));
+    __SET_VAR(data__->,CNT1,,(__GET_VAR(data__->CNT1,) + 1));
+    if ((__GET_VAR(data__->CNT1,) == 100)) {
+      __SET_EXTERNAL(data__->,RELAY3VALUE0,,1);
+    };
+    if ((__GET_VAR(data__->CNT1,) == 500)) {
+      __SET_EXTERNAL(data__->,RELAY3VALUE0,,0);
+    };
+  };
+  __SET_VAR(data__->,OUT1,,__GET_VAR(data__->CNT1,));
+  __SET_VAR(data__->,OUT0,,__GET_VAR(data__->CNT0,));
+
+  goto __end;
+
+__end:
+  return;
+} // COUNTERST_body__() 
+
+
+
+
+
+void PLC_PRG_init__(PLC_PRG *data__, BOOL retain) {
+  __INIT_VAR(data__->RESET,__BOOL_LITERAL(FALSE),retain)
+  __INIT_VAR(data__->CNT0,0,retain)
+  __INIT_VAR(data__->CNT1,0,retain)
+  COUNTERST_init__(&data__->COUNTERST0,retain);
+}
+
+// Code part
+void PLC_PRG_body__(PLC_PRG *data__) {
+  // Initialise TEMP variables
+
+  __SET_VAR(data__->COUNTERST0.,RESET,,__GET_VAR(data__->RESET,));
+  COUNTERST_body__(&data__->COUNTERST0);
+  __SET_VAR(data__->,CNT1,,__GET_VAR(data__->COUNTERST0.OUT1,));
+  __SET_VAR(data__->,CNT0,,__GET_VAR(data__->COUNTERST0.OUT0,));
+
+  goto __end;
+
+__end:
+  return;
+} // PLC_PRG_body__() 
+
+
+
+
+

Beremiz/beremiz_tutorial_opc_ua/build/POUS.h

+#include "beremiz.h"
+#ifndef __POUS_H
+#define __POUS_H
+
+#include "accessor.h"
+#include "iec_std_lib.h"
+
+__DECLARE_ENUMERATED_TYPE(LOGLEVEL,
+  LOGLEVEL__CRITICAL,
+  LOGLEVEL__WARNING,
+  LOGLEVEL__INFO,
+  LOGLEVEL__DEBUG
+)
+// FUNCTION_BLOCK LOGGER
+// Data part
+typedef struct {
+  // FB Interface - IN, OUT, IN_OUT variables
+  __DECLARE_VAR(BOOL,EN)
+  __DECLARE_VAR(BOOL,ENO)
+  __DECLARE_VAR(BOOL,TRIG)
+  __DECLARE_VAR(STRING,MSG)
+  __DECLARE_VAR(LOGLEVEL,LEVEL)
+
+  // FB private variables - TEMP, private and located variables
+  __DECLARE_VAR(BOOL,TRIG0)
+
+} LOGGER;
+
+void LOGGER_init__(LOGGER *data__, BOOL retain);
+// Code part
+void LOGGER_body__(LOGGER *data__);
+// FUNCTION_BLOCK PYTHON_EVAL
+// Data part
+typedef struct {
+  // FB Interface - IN, OUT, IN_OUT variables
+  __DECLARE_VAR(BOOL,EN)
+  __DECLARE_VAR(BOOL,ENO)
+  __DECLARE_VAR(BOOL,TRIG)
+  __DECLARE_VAR(STRING,CODE)
+  __DECLARE_VAR(BOOL,ACK)
+  __DECLARE_VAR(STRING,RESULT)
+
+  // FB private variables - TEMP, private and located variables
+  __DECLARE_VAR(DWORD,STATE)
+  __DECLARE_VAR(STRING,BUFFER)
+  __DECLARE_VAR(STRING,PREBUFFER)
+  __DECLARE_VAR(BOOL,TRIGM1)
+  __DECLARE_VAR(BOOL,TRIGGED)
+
+} PYTHON_EVAL;
+
+void PYTHON_EVAL_init__(PYTHON_EVAL *data__, BOOL retain);
+// Code part
+void PYTHON_EVAL_body__(PYTHON_EVAL *data__);
+// FUNCTION_BLOCK PYTHON_POLL
+// Data part
+typedef struct {
+  // FB Interface - IN, OUT, IN_OUT variables
+  __DECLARE_VAR(BOOL,EN)
+  __DECLARE_VAR(BOOL,ENO)
+  __DECLARE_VAR(BOOL,TRIG)
+  __DECLARE_VAR(STRING,CODE)
+  __DECLARE_VAR(BOOL,ACK)
+  __DECLARE_VAR(STRING,RESULT)
+
+  // FB private variables - TEMP, private and located variables
+  __DECLARE_VAR(DWORD,STATE)
+  __DECLARE_VAR(STRING,BUFFER)
+  __DECLARE_VAR(STRING,PREBUFFER)
+  __DECLARE_VAR(BOOL,TRIGM1)
+  __DECLARE_VAR(BOOL,TRIGGED)
+
+} PYTHON_POLL;
+
+void PYTHON_POLL_init__(PYTHON_POLL *data__, BOOL retain);
+// Code part
+void PYTHON_POLL_body__(PYTHON_POLL *data__);
+// FUNCTION_BLOCK PYTHON_GEAR
+// Data part
+typedef struct {
+  // FB Interface - IN, OUT, IN_OUT variables
+  __DECLARE_VAR(BOOL,EN)
+  __DECLARE_VAR(BOOL,ENO)
+  __DECLARE_VAR(UINT,N)
+  __DECLARE_VAR(BOOL,TRIG)
+  __DECLARE_VAR(STRING,CODE)
+  __DECLARE_VAR(BOOL,ACK)
+  __DECLARE_VAR(STRING,RESULT)
+
+  // FB private variables - TEMP, private and located variables
+  PYTHON_EVAL PY_EVAL;
+  __DECLARE_VAR(UINT,COUNTER)
+  __DECLARE_VAR(UINT,_TMP_ADD10_OUT)
+  __DECLARE_VAR(BOOL,_TMP_EQ13_OUT)
+  __DECLARE_VAR(UINT,_TMP_SEL15_OUT)
+  __DECLARE_VAR(BOOL,_TMP_AND7_OUT)
+
+} PYTHON_GEAR;
+
+void PYTHON_GEAR_init__(PYTHON_GEAR *data__, BOOL retain);
+// Code part
+void PYTHON_GEAR_body__(PYTHON_GEAR *data__);
+// FUNCTION_BLOCK COUNTERST
+// Data part
+typedef struct {
+  // FB Interface - IN, OUT, IN_OUT variables
+  __DECLARE_VAR(BOOL,EN)
+  __DECLARE_VAR(BOOL,ENO)
+  __DECLARE_VAR(BOOL,RESET)
+  __DECLARE_VAR(INT,OUT1)
+  __DECLARE_VAR(INT,OUT0)
+
+  // FB private variables - TEMP, private and located variables
+  __DECLARE_VAR(INT,CNT1)
+  __DECLARE_VAR(INT,CNT0)
+  __DECLARE_EXTERNAL(INT,RESETCOUNTERVALUE)
+  __DECLARE_EXTERNAL(BOOL,RELAY0VALUE)
+  __DECLARE_EXTERNAL(BOOL,RELAY1VALUE)
+  __DECLARE_EXTERNAL(BOOL,RELAY2VALUE)
+  __DECLARE_EXTERNAL(BOOL,RELAY3VALUE)
+  __DECLARE_EXTERNAL(DINT,RELAY3VALUE0)
+
+} COUNTERST;
+
+void COUNTERST_init__(COUNTERST *data__, BOOL retain);
+// Code part
+void COUNTERST_body__(COUNTERST *data__);
+// PROGRAM PLC_PRG
+// Data part
+typedef struct {
+  // PROGRAM Interface - IN, OUT, IN_OUT variables
+  __DECLARE_VAR(BOOL,RESET)
+  __DECLARE_VAR(INT,CNT0)
+  __DECLARE_VAR(INT,CNT1)
+
+  // PROGRAM private variables - TEMP, private and located variables
+  COUNTERST COUNTERST0;
+
+} PLC_PRG;
+
+void PLC_PRG_init__(PLC_PRG *data__, BOOL retain);
+// Code part
+void PLC_PRG_body__(PLC_PRG *data__);
+#endif //__POUS_H

Beremiz/beremiz_tutorial_opc_ua/build/VARIABLES.csv

+// Programs
+0;CONFIG.RESOURCE1.INSTANCE0;PLC_PRG;
+
+// Variables
+0;VAR;CONFIG.RESETCOUNTERVALUE;CONFIG.RESETCOUNTERVALUE;INT;INT;
+1;OUT;CONFIG.RELAY0VALUE;CONFIG.RELAY0VALUE;BOOL;BOOL;
+2;OUT;CONFIG.RELAY1VALUE;CONFIG.RELAY1VALUE;BOOL;BOOL;
+3;OUT;CONFIG.RELAY2VALUE;CONFIG.RELAY2VALUE;BOOL;BOOL;
+4;OUT;CONFIG.RELAY3VALUE;CONFIG.RELAY3VALUE;BOOL;BOOL;
+5;OUT;CONFIG.RELAY3VALUE0;CONFIG.RELAY3VALUE0;DINT;DINT;
+6;FB;CONFIG.RESOURCE1.INSTANCE0;CONFIG.RESOURCE1.INSTANCE0;PLC_PRG;;
+7;VAR;CONFIG.RESOURCE1.INSTANCE0.RESET;CONFIG.RESOURCE1.INSTANCE0.RESET;BOOL;BOOL;
+8;VAR;CONFIG.RESOURCE1.INSTANCE0.CNT0;CONFIG.RESOURCE1.INSTANCE0.CNT0;INT;INT;
+9;VAR;CONFIG.RESOURCE1.INSTANCE0.CNT1;CONFIG.RESOURCE1.INSTANCE0.CNT1;INT;INT;
+10;FB;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0;COUNTERST;;
+11;VAR;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.EN;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.EN;BOOL;BOOL;
+12;VAR;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.ENO;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.ENO;BOOL;BOOL;
+13;VAR;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RESET;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RESET;BOOL;BOOL;
+14;VAR;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.OUT1;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.OUT1;INT;INT;
+15;VAR;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.OUT0;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.OUT0;INT;INT;
+16;VAR;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.CNT1;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.CNT1;INT;INT;
+17;VAR;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.CNT0;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.CNT0;INT;INT;
+18;EXT;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RESETCOUNTERVALUE;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RESETCOUNTERVALUE;INT;INT;
+19;EXT;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RELAY0VALUE;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RELAY0VALUE;BOOL;BOOL;
+20;EXT;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RELAY1VALUE;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RELAY1VALUE;BOOL;BOOL;
+21;EXT;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RELAY2VALUE;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RELAY2VALUE;BOOL;BOOL;
+22;EXT;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RELAY3VALUE;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RELAY3VALUE;BOOL;BOOL;
+23;EXT;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RELAY3VALUE0;CONFIG.RESOURCE1.INSTANCE0.COUNTERST0.RELAY3VALUE0;DINT;DINT;
+
+
+// Ticktime
+20000000

Beremiz/beremiz_tutorial_opc_ua/build/beremiz.h

+#ifndef _BEREMIZ_H_
+#define _BEREMIZ_H_
+
+/* Beremiz' header file for use by extensions */
+
+#include "iec_types.h"
+
+#define LOG_LEVELS 4
+#define LOG_CRITICAL 0
+#define LOG_WARNING 1
+#define LOG_INFO 2
+#define LOG_DEBUG 3
+
+extern unsigned long long common_ticktime__;
+
+#ifdef TARGET_LOGGING_DISABLE
+static inline int LogMessage(uint8_t level, char* buf, uint32_t size)
+{
+	(void)level;
+	(void)buf;
+	(void)size;
+	return 0;
+}
+#else
+int     LogMessage(uint8_t level, char* buf, uint32_t size);
+#endif
+
+long AtomicCompareExchange(long* atomicvar,long compared, long exchange);
+void *create_RT_to_nRT_signal(char* name);
+void delete_RT_to_nRT_signal(void* handle);
+int wait_RT_to_nRT_signal(void* handle);
+int unblock_RT_to_nRT_signal(void* handle);
+void nRT_reschedule(void);
+
+#endif

Beremiz/beremiz_tutorial_opc_ua/build/config.c

+/*******************************************/
+/*     FILE GENERATED BY iec2c             */
+/* Editing this file is not recommended... */
+/*******************************************/
+
+#include "iec_std_lib.h"
+
+#include "accessor.h"
+
+#include "POUS.h"
+
+// CONFIGURATION CONFIG
+__DECLARE_GLOBAL(INT,CONFIG,RESETCOUNTERVALUE)
+__DECLARE_GLOBAL_LOCATION(BOOL,__QX0_0_0_0)
+__DECLARE_GLOBAL_LOCATED(BOOL,CONFIG,RELAY0VALUE)
+__DECLARE_GLOBAL_LOCATION(BOOL,__QX0_0_1_1)
+__DECLARE_GLOBAL_LOCATED(BOOL,CONFIG,RELAY1VALUE)
+__DECLARE_GLOBAL_LOCATION(BOOL,__QX0_0_2_2)
+__DECLARE_GLOBAL_LOCATED(BOOL,CONFIG,RELAY2VALUE)
+__DECLARE_GLOBAL_LOCATION(BOOL,__QX0_0_3_3)
+__DECLARE_GLOBAL_LOCATED(BOOL,CONFIG,RELAY3VALUE)
+__DECLARE_GLOBAL_LOCATION(DINT,__QD1_0)
+__DECLARE_GLOBAL_LOCATED(DINT,CONFIG,RELAY3VALUE0)
+
+void RESOURCE1_init__(void);
+
+void config_init__(void) {
+  BOOL retain;
+  retain = 0;
+  __INIT_GLOBAL(INT,RESETCOUNTERVALUE,__INITIAL_VALUE(0),retain)
+  __INIT_GLOBAL_LOCATED(CONFIG,RELAY0VALUE,__QX0_0_0_0,retain)
+  __INIT_GLOBAL(BOOL,RELAY0VALUE,__INITIAL_VALUE(0),retain)
+  __INIT_GLOBAL_LOCATED(CONFIG,RELAY1VALUE,__QX0_0_1_1,retain)
+  __INIT_GLOBAL(BOOL,RELAY1VALUE,__INITIAL_VALUE(0),retain)
+  __INIT_GLOBAL_LOCATED(CONFIG,RELAY2VALUE,__QX0_0_2_2,retain)
+  __INIT_GLOBAL(BOOL,RELAY2VALUE,__INITIAL_VALUE(0),retain)
+  __INIT_GLOBAL_LOCATED(CONFIG,RELAY3VALUE,__QX0_0_3_3,retain)
+  __INIT_GLOBAL(BOOL,RELAY3VALUE,__INITIAL_VALUE(0),retain)
+  __INIT_GLOBAL_LOCATED(CONFIG,RELAY3VALUE0,__QD1_0,retain)
+  __INIT_GLOBAL(DINT,RELAY3VALUE0,__INITIAL_VALUE(0),retain)
+  RESOURCE1_init__();
+}
+
+void RESOURCE1_run__(unsigned long tick);
+
+void config_run__(unsigned long tick) {
+  RESOURCE1_run__(tick);
+}
+unsigned long long common_ticktime__ = 20000000ULL * 1ULL; /*ns*/
+unsigned long greatest_tick_count__ = (unsigned long)0UL; /*tick*/

Beremiz/beremiz_tutorial_opc_ua/build/config.h

+#include "beremiz.h"
+__DECLARE_GLOBAL_PROTOTYPE(INT,RESETCOUNTERVALUE)
+__DECLARE_GLOBAL_PROTOTYPE(BOOL,RELAY0VALUE)
+__DECLARE_GLOBAL_PROTOTYPE(BOOL,RELAY1VALUE)
+__DECLARE_GLOBAL_PROTOTYPE(BOOL,RELAY2VALUE)
+__DECLARE_GLOBAL_PROTOTYPE(BOOL,RELAY3VALUE)
+__DECLARE_GLOBAL_PROTOTYPE(DINT,RELAY3VALUE0)
+

Beremiz/beremiz_tutorial_opc_ua/build/extra_files/runtime_0_modbus_websettings.py

+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# This file is part of Beremiz runtime.
+#
+# Copyright (C) 2020: Mario de Sousa
+#
+# See COPYING.Runtime file for copyrights details.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+
+
+
+##############################################################################################
+# This file implements an extension to the web server embedded in the Beremiz_service.py     #
+# runtime manager (webserver is in runtime/NevowServer.py).                                  #
+#                                                                                            #
+# The extension implemented in this file allows for runtime configuration                    #
+# of Modbus plugin parameters                                                                #
+##############################################################################################
+
+
+
+import json
+import os
+import ctypes
+import string
+import hashlib
+
+from formless import annotate, webform
+
+import runtime.NevowServer as NS
+
+# Directory in which to store the persistent configurations
+# Should be a directory that does not get wiped on reboot!
+_ModbusConfFiledir = WorkingDir
+
+# List of all Web Extension Setting nodes we are handling.
+# One WebNode each for:
+#   - Modbus TCP client 
+#   - Modbus TCP server
+#   - Modbus RTU client
+#   - Modbus RTU slave
+# configured in the loaded PLC (i.e. the .so file loaded into memory)
+# Each entry will be a dictionary. See _AddWebNode() for the details
+# of the data structure in each entry.
+_WebNodeList = []
+
+
+
+
+class MB_StrippedString(annotate.String):
+    def __init__(self, *args, **kwargs):
+        annotate.String.__init__(self, strip = True, *args, **kwargs)
+
+
+class MB_StopBits(annotate.Choice):
+    _choices = [0, 1, 2]
+
+    def coerce(self, val, configurable):
+        return int(val)
+    def __init__(self, *args, **kwargs):
+        annotate.Choice.__init__(self, choices = self._choices, *args, **kwargs)
+
+
+class MB_Baud(annotate.Choice):
+    _choices = [110, 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200]
+
+    def coerce(self, val, configurable):
+        return int(val)
+    def __init__(self, *args, **kwargs):
+        annotate.Choice.__init__(self, choices = self._choices, *args, **kwargs)
+
+
+class MB_Parity(annotate.Choice):
+    # For more info on what this class really does, have a look at the code in
+    # file twisted/nevow/annotate.py
+    # grab this code from $git clone https://github.com/twisted/nevow/
+    # 
+    # Warning: do _not_ name this variable choice[] without underscore, as that name is
+    # already used for another similar variable by the underlying class annotate.Choice
+    _choices = [  0,      1,      2  ]
+    _label   = ["none", "odd", "even"]
+    
+    def choice_to_label(self, key):
+        #PLCObject.LogMessage("Modbus web server extension::choice_to_label()  " + str(key))
+        return self._label[key]
+    
+    def coerce(self, val, configurable):
+        """Coerce a value with the help of an object, which is the object
+        we are configuring.
+        """
+        # Basically, make sure the value the user introduced is valid, and transform
+        # into something that is valid if necessary or mark it as an error 
+        # (by raising an exception ??).
+        #
+        # We are simply using this functions to transform the input value (a string)
+        # into an integer. Note that although the available options are all
+        # integers (0, 1 or 2), even though what is shown on the user interface
+        # are actually strings, i.e. the labels), these parameters are for some 
+        # reason being parsed as strings, so we need to map them back to an
+        # integer.
+        #
+        #PLCObject.LogMessage("Modbus web server extension::coerce  " + val )
+        return int(val)
+
+    def __init__(self, *args, **kwargs):
+        annotate.Choice.__init__(self, 
+                                 choices   = self._choices,
+                                 stringify = self.choice_to_label,
+                                 *args, **kwargs)
+
+
+
+# Parameters we will need to get from the C code, but that will not be shown
+# on the web interface. Common to all modbus entry types (client/server, tcp/rtu/ascii)
+#
+# The annotate type entry is basically useless and is completely ignored.
+# We kee that entry so that this list can later be correctly merged with the
+# following lists...
+General_parameters = [
+    #    param. name       label                        ctype type         annotate type
+    # (C code var name)   (used on web interface)      (C data type)       (web data type)
+    #                                                                      (annotate.String,
+    #                                                                       annotate.Integer, ...)
+    ("config_name"      , _("")                      , ctypes.c_char_p,    annotate.String),
+    ("addr_type"        , _("")                      , ctypes.c_char_p,    annotate.String)
+    ]                                                                      
+                                                                           
+# Parameters we will need to get from the C code, and that _will_ be shown
+# on the web interface.
+TCPclient_parameters = [                                                   
+    #    param. name       label                        ctype type         annotate type
+    # (C code var name)   (used on web interface)      (C data type)       (web data type)
+    #                                                                      (annotate.String,
+    #                                                                       annotate.Integer, ...)
+    ("host"             , _("Remote IP Address")     , ctypes.c_char_p,    MB_StrippedString),
+    ("port"             , _("Remote Port Number")    , ctypes.c_char_p,    MB_StrippedString),
+    ("comm_period"      , _("Invocation Rate (ms)")  , ctypes.c_ulonglong, annotate.Integer )
+    ]
+
+RTUclient_parameters = [                                                   
+    #    param. name       label                        ctype type         annotate type
+    # (C code var name)   (used on web interface)      (C data type)       (web data type)
+    #                                                                      (annotate.String,
+    #                                                                       annotate.Integer, ...)
+    ("device"           , _("Serial Port")           , ctypes.c_char_p,    MB_StrippedString),
+    ("baud"             , _("Baud Rate")             , ctypes.c_int,       MB_Baud         ),
+    ("parity"           , _("Parity")                , ctypes.c_int,       MB_Parity       ),
+    ("stop_bits"        , _("Stop Bits")             , ctypes.c_int,       MB_StopBits     ),
+    ("comm_period"      , _("Invocation Rate (ms)")  , ctypes.c_ulonglong, annotate.Integer)
+    ]
+
+TCPserver_parameters = [                                                   
+    #    param. name       label                        ctype type         annotate type
+    # (C code var name)   (used on web interface)      (C data type)       (web data type)
+    #                                                                      (annotate.String,
+    #                                                                       annotate.Integer, ...)
+    ("host"             , _("Local IP Address")      , ctypes.c_char_p,    MB_StrippedString),
+    ("port"             , _("Local Port Number")     , ctypes.c_char_p,    MB_StrippedString),
+    ("slave_id"         , _("Slave ID")              , ctypes.c_ubyte,     annotate.Integer )
+    ]
+
+RTUslave_parameters = [                                                   
+    #    param. name       label                        ctype type         annotate type
+    # (C code var name)   (used on web interface)      (C data type)       (web data type)
+    #                                                                      (annotate.String,
+    #                                                                       annotate.Integer, ...)
+    ("device"           , _("Serial Port")           , ctypes.c_char_p,    MB_StrippedString),
+    ("baud"             , _("Baud Rate")             , ctypes.c_int,       MB_Baud         ),
+    ("parity"           , _("Parity")                , ctypes.c_int,       MB_Parity       ),
+    ("stop_bits"        , _("Stop Bits")             , ctypes.c_int,       MB_StopBits     ),
+    ("slave_id"         , _("Slave ID")              , ctypes.c_ubyte,     annotate.Integer)
+    ]
+
+
+
+
+# Dictionary containing List of Web viewable parameters
+# Note: the dictionary key must be the same as the string returned by the 
+# __modbus_get_ClientNode_addr_type()
+# __modbus_get_ServerNode_addr_type()
+# functions implemented in C (see modbus/mb_runtime.c)
+_client_WebParamListDict = {}
+_client_WebParamListDict["tcp"  ] = TCPclient_parameters
+_client_WebParamListDict["rtu"  ] = RTUclient_parameters
+_client_WebParamListDict["ascii"] = []  # (Note: ascii not yet implemented in Beremiz modbus plugin)
+
+_server_WebParamListDict = {}
+_server_WebParamListDict["tcp"  ] = TCPserver_parameters
+_server_WebParamListDict["rtu"  ] = RTUslave_parameters
+_server_WebParamListDict["ascii"] = []  # (Note: ascii not yet implemented in Beremiz modbus plugin)
+
+WebParamListDictDict = {}
+WebParamListDictDict['client'] = _client_WebParamListDict
+WebParamListDictDict['server'] = _server_WebParamListDict
+
+
+
+
+
+
+def _SetModbusSavedConfiguration(WebNode_id, newConfig):
+    """ Stores a dictionary in a persistant file containing the Modbus parameter configuration """
+    WebNode_entry = _WebNodeList[WebNode_id]
+
+    if WebNode_entry["DefaultConfiguration"] == newConfig:
+
+        _DelModbusSavedConfiguration(WebNode_id)
+        WebNode_entry["ModbusSavedConfiguration"] = None
+
+    else:
+
+        # Add the addr_type and node_type to the data that will be saved to file
+        # This allows us to confirm the saved data contains the correct addr_type
+        # when loading from file
+        save_info = {}
+        save_info["addr_type"] = WebNode_entry["addr_type"]
+        save_info["node_type"] = WebNode_entry["node_type"]
+        save_info["config"   ] = newConfig
+        
+        filename = WebNode_entry["filename"]
+
+        with open(os.path.realpath(filename), 'w') as f:
+            json.dump(save_info, f, sort_keys=True, indent=4)
+            
+        WebNode_entry["ModbusSavedConfiguration"] = newConfig
+
+
+
+
+def _DelModbusSavedConfiguration(WebNode_id):
+    """ Deletes the file cotaining the persistent Modbus configuration """
+    filename = _WebNodeList[WebNode_id]["filename"]
+    
+    if os.path.exists(filename):
+        os.remove(filename)
+
+
+
+
+def _GetModbusSavedConfiguration(WebNode_id):
+    """
+    Returns a dictionary containing the Modbus parameter configuration
+    that was last saved to file. If no file exists, or file contains 
+    wrong addr_type (i.e. 'tcp', 'rtu' or 'ascii' -> does not match the
+    addr_type of the WebNode_id), then return None
+    """
+    filename = _WebNodeList[WebNode_id]["filename"]
+    try:
+        #if os.path.isfile(filename):
+        save_info = json.load(open(os.path.realpath(filename)))
+    except Exception:    
+        return None
+
+    if save_info["addr_type"] != _WebNodeList[WebNode_id]["addr_type"]:
+        return None
+    if save_info["node_type"] != _WebNodeList[WebNode_id]["node_type"]:
+        return None
+    if "config" not in save_info:
+        return None
+    
+    saved_config = save_info["config"]
+    
+    #if _CheckConfiguration(saved_config):
+    #    return saved_config
+    #else:
+    #    return None
+
+    return saved_config
+
+
+
+def _GetModbusPLCConfiguration(WebNode_id):
+    """
+    Returns a dictionary containing the current Modbus parameter configuration
+    stored in the C variables in the loaded PLC (.so file)
+    """
+    current_config = {}
+    C_node_id      = _WebNodeList[WebNode_id]["C_node_id"]
+    WebParamList   = _WebNodeList[WebNode_id]["WebParamList"]
+    GetParamFuncs  = _WebNodeList[WebNode_id]["GetParamFuncs"]
+
+    for par_name, x1, x2, x3 in WebParamList:
+        value = GetParamFuncs[par_name](C_node_id)
+        if value is not None:
+            current_config[par_name] = value
+    
+    return current_config
+
+
+
+def _SetModbusPLCConfiguration(WebNode_id, newconfig):
+    """
+    Stores the Modbus parameter configuration into the
+    the C variables in the loaded PLC (.so file)
+    """
+    C_node_id      = _WebNodeList[WebNode_id]["C_node_id"]
+    SetParamFuncs  = _WebNodeList[WebNode_id]["SetParamFuncs"]
+
+    for par_name in newconfig:
+        value = newconfig[par_name]
+        if value is not None:
+            SetParamFuncs[par_name](C_node_id, value)
+            
+
+
+
+def _GetModbusWebviewConfigurationValue(ctx, WebNode_id, argument):
+    """
+    Callback function, called by the web interface (NevowServer.py)
+    to fill in the default value of each parameter of the web form
+    
+    Note that the real callback function is a dynamically created function that
+    will simply call this function to do the work. It will also pass the WebNode_id 
+    as a parameter.
+    """    
+    try:
+        return _WebNodeList[WebNode_id]["WebviewConfiguration"][argument.name]
+    except Exception:
+        return ""
+
+
+
+def OnModbusButtonSave(**kwargs):
+    """
+    Function called when user clicks 'Save' button in web interface
+    The function will configure the Modbus plugin in the PLC with the values
+    specified in the web interface. However, values must be validated first!
+    
+    Note that this function does not get called directly. The real callback
+    function is the dynamic __OnButtonSave() function, which will add the 
+    "WebNode_id" argument, and call this function to do the work.
+    """
+
+    #PLCObject.LogMessage("Modbus web server extension::OnModbusButtonSave()  Called")
+    
+    newConfig    = {}
+    WebNode_id   =  kwargs.get("WebNode_id", None)
+    WebParamList = _WebNodeList[WebNode_id]["WebParamList"]
+    
+    for par_name, x1, x2, x3 in WebParamList:
+        value = kwargs.get(par_name, None)
+        if value is not None:
+            newConfig[par_name] = value
+
+    # First check if configuration is OK.
+    # Note that this is not currently required, as we use drop down choice menus
+    # for baud, parity and sop bits, so the values should always be correct!
+    #if not _CheckWebConfiguration(newConfig):
+    #    return
+    
+    # store to file the new configuration so that 
+    # we can recoup the configuration the next time the PLC
+    # has a cold start (i.e. when Beremiz_service.py is retarted)
+    _SetModbusSavedConfiguration(WebNode_id, newConfig)
+
+    # Configure PLC with the current Modbus parameters
+    _SetModbusPLCConfiguration(WebNode_id, newConfig)
+
+    # Update the viewable configuration
+    # The PLC may have coerced the values on calling _SetModbusPLCConfiguration()
+    # so we do not set it directly to newConfig
+    _WebNodeList[WebNode_id]["WebviewConfiguration"] = _GetModbusPLCConfiguration(WebNode_id)
+
+
+
+def OnModbusButtonReset(**kwargs):
+    """
+    Function called when user clicks 'Delete' button in web interface
+    The function will delete the file containing the persistent
+    Modbus configution
+    """
+
+    WebNode_id = kwargs.get("WebNode_id", None)
+    
+    # Delete the file
+    _DelModbusSavedConfiguration(WebNode_id)
+
+    # Set the current configuration to the default (hardcoded in C)
+    new_config = _WebNodeList[WebNode_id]["DefaultConfiguration"]
+    _SetModbusPLCConfiguration(WebNode_id, new_config)
+    
+    #Update the webviewconfiguration
+    _WebNodeList[WebNode_id]["WebviewConfiguration"] = new_config
+    
+    # Reset ModbusSavedConfiguration
+    _WebNodeList[WebNode_id]["ModbusSavedConfiguration"] = None
+    
+
+
+
+
+def _AddWebNode(C_node_id, node_type, GetParamFuncs, SetParamFuncs):
+    """
+    Load from the compiled code (.so file, aloready loaded into memmory)
+    the configuration parameters of a specific Modbus plugin node.
+    This function works with both client and server nodes, depending on the
+    Get/SetParamFunc dictionaries passed to it (either the client or the server
+    node versions of the Get/Set functions)
+    """
+    WebNode_entry = {}
+
+    # Get the config_name from the C code...
+    config_name = GetParamFuncs["config_name"](C_node_id)
+    # Get the addr_type from the C code...
+    # addr_type will be one of "tcp", "rtu" or "ascii"
+    addr_type   = GetParamFuncs["addr_type"  ](C_node_id)   
+    # For some operations we cannot use the config name (e.g. filename to store config)
+    # because the user may be using characters that are invalid for that purpose ('/' for
+    # example), so we create a hash of the config_name, and use that instead.
+    config_hash = hashlib.md5(config_name).hexdigest()
+    
+    #PLCObject.LogMessage("Modbus web server extension::_AddWebNode("+str(C_node_id)+") config_name="+config_name)
+
+    # Add the new entry to the global list
+    # Note: it is OK, and actually necessary, to do this _before_ seting all the parameters in WebNode_entry
+    #       WebNode_entry will be stored as a reference, so we can later insert parameters at will.
+    global _WebNodeList
+    _WebNodeList.append(WebNode_entry)
+    WebNode_id = len(_WebNodeList) - 1
+
+    # store all WebNode relevant data for future reference
+    #
+    # Note that "WebParamList" will reference one of:
+    #  - TCPclient_parameters, TCPserver_parameters, RTUclient_parameters, RTUslave_parameters
+    WebNode_entry["C_node_id"    ] = C_node_id
+    WebNode_entry["config_name"  ] = config_name 
+    WebNode_entry["config_hash"  ] = config_hash
+    WebNode_entry["filename"     ] = os.path.join(_ModbusConfFiledir, "Modbus_config_" + config_hash + ".json")
+    WebNode_entry["GetParamFuncs"] = GetParamFuncs
+    WebNode_entry["SetParamFuncs"] = SetParamFuncs
+    WebNode_entry["WebParamList" ] = WebParamListDictDict[node_type][addr_type] 
+    WebNode_entry["addr_type"    ] = addr_type  # 'tcp', 'rtu', or 'ascii' (as returned by C function)
+    WebNode_entry["node_type"    ] = node_type  # 'client', 'server'
+        
+    
+    # Dictionary that contains the Modbus configuration currently being shown
+    # on the web interface
+    # This configuration will almost always be identical to the current
+    # configuration in the PLC (i.e., the current state stored in the 
+    # C variables in the .so file).
+    # The configuration viewed on the web will only be different to the current 
+    # configuration when the user edits the configuration, and when
+    # the user asks to save an edited configuration that contains an error.
+    WebNode_entry["WebviewConfiguration"] = None
+
+    # Upon PLC load, this Dictionary is initialised with the Modbus configuration
+    # hardcoded in the C file
+    # (i.e. the configuration inserted in Beremiz IDE when project was compiled)
+    WebNode_entry["DefaultConfiguration"] = _GetModbusPLCConfiguration(WebNode_id)
+    WebNode_entry["WebviewConfiguration"] = WebNode_entry["DefaultConfiguration"]
+    
+    # Dictionary that stores the Modbus configuration currently stored in a file
+    # Currently only used to decide whether or not to show the "Delete" button on the
+    # web interface (only shown if "ModbusSavedConfiguration" is not None)
+    SavedConfig = _GetModbusSavedConfiguration(WebNode_id)
+    WebNode_entry["ModbusSavedConfiguration"] = SavedConfig
+    
+    if SavedConfig is not None:
+        _SetModbusPLCConfiguration(WebNode_id, SavedConfig)
+        WebNode_entry["WebviewConfiguration"] = SavedConfig
+        
+    # Define the format for the web form used to show/change the current parameters
+    # We first declare a dynamic function to work as callback to obtain the default values for each parameter
+    # Note: We transform every parameter into a string
+    #       This is not strictly required for parameters of type annotate.Integer that will correctly
+    #           accept the default value as an Integer python object
+    #       This is obviously also not required for parameters of type annotate.String, that are
+    #           always handled as strings.
+    #       However, the annotate.Choice parameters (and all parameters that derive from it,
+    #           sucn as Parity, Baud, etc.) require the default value as a string
+    #           even though we store it as an integer, which is the data type expected
+    #           by the set_***() C functions in mb_runtime.c
+    def __GetWebviewConfigurationValue(ctx, argument):
+        return str(_GetModbusWebviewConfigurationValue(ctx, WebNode_id, argument))
+    
+    webFormInterface = [(name, web_dtype (label=web_label, default=__GetWebviewConfigurationValue)) 
+                    for name, web_label, c_dtype, web_dtype in WebNode_entry["WebParamList"]]
+
+    # Configure the web interface to include the Modbus config parameters
+    def __OnButtonSave(**kwargs):
+        OnModbusButtonSave(WebNode_id=WebNode_id, **kwargs)
+
+    WebSettings = NS.newExtensionSetting("Modbus #"+ str(WebNode_id), config_hash)
+
+    WebSettings.addSettings(
+        "ModbusConfigParm"          + config_hash,     # name (internal, may not contain spaces, ...)
+        _("Modbus Configuration: ") + config_name,     # description (user visible label)
+        webFormInterface,                              # fields
+        _("Apply"), # button label
+        __OnButtonSave)                                # callback   
+    
+    def __OnButtonReset(**kwargs):
+        return OnModbusButtonReset(WebNode_id = WebNode_id, **kwargs)
+            
+    def getModbusConfigStatus():
+        if WebNode_entry["WebviewConfiguration"] == WebNode_entry["DefaultConfiguration"]:
+            return "Unchanged"
+        return "Modified"
+
+    WebSettings.addSettings(
+        "ModbusConfigDelSaved"      + config_hash,  # name (internal, may not contain spaces, ...)
+        _("Modbus Configuration: ") + config_name,  # description (user visible label)
+        [ ("status",
+           annotate.String(label=_("Current state"),
+                           immutable=True,
+                           default=lambda *k:getModbusConfigStatus())),
+        ],                                       # fields  (empty, no parameters required!)
+        _("Reset"), # button label
+        __OnButtonReset)
+
+
+
+
+def _runtime_0_modbus_websettings_init():
+    """
+    Callback function, called (by PLCObject.py) when a new PLC program
+    (i.e. XXX.so file) is transfered to the PLC runtime
+    and loaded into memory
+    """
+
+    #PLCObject.LogMessage("Modbus web server extension::OnLoadPLC() Called...")
+
+    if PLCObject.PLClibraryHandle is None:
+        # PLC was loaded but we don't have access to the library of compiled code (.so lib)?
+        # Hmm... This shold never occur!! 
+        return  
+    
+    # Get the number of Modbus Client and Servers (Modbus plugin)
+    # configured in the currently loaded PLC project (i.e., the .so file)
+    # If the "__modbus_plugin_client_node_count" 
+    # or the "__modbus_plugin_server_node_count" C variables 
+    # are not present in the .so file we conclude that the currently loaded 
+    # PLC does not have the Modbus plugin included (situation (2b) described above init())
+    try:
+        # XXX TODO : stop reading from PLC .so file. This code is template code
+        #            that can use modbus extension build data, such as client node count.
+        client_count = ctypes.c_int.in_dll(PLCObject.PLClibraryHandle, "__modbus_plugin_client_node_count").value
+        server_count = ctypes.c_int.in_dll(PLCObject.PLClibraryHandle, "__modbus_plugin_server_node_count").value
+    except Exception:
+        # Loaded PLC does not have the Modbus plugin => nothing to do
+        #   (i.e. do _not_ configure and make available the Modbus web interface)
+        return
+
+    if client_count < 0: client_count = 0
+    if server_count < 0: server_count = 0
+    
+    if (client_count == 0) and (server_count == 0):
+        # The Modbus plugin in the loaded PLC does not have any client and servers configured
+        #  => nothing to do (i.e. do _not_ configure and make available the Modbus web interface)
+        return
+    
+    # Map the get/set functions (written in C code) we will be using to get/set the configuration parameters
+    # Will contain references to the C functions (implemented in beremiz/modbus/mb_runtime.c)
+    GetClientParamFuncs = {}
+    SetClientParamFuncs = {}
+    GetServerParamFuncs = {}
+    SetServerParamFuncs = {}
+
+    # XXX TODO : stop reading from PLC .so file. This code is template code
+    #            that can use modbus extension build data
+    for name, web_label, c_dtype, web_dtype in TCPclient_parameters + RTUclient_parameters + General_parameters:
+        ParamFuncName                      = "__modbus_get_ClientNode_" + name        
+        GetClientParamFuncs[name]          = getattr(PLCObject.PLClibraryHandle, ParamFuncName)
+        GetClientParamFuncs[name].restype  = c_dtype
+        GetClientParamFuncs[name].argtypes = [ctypes.c_int]
+        
+    for name, web_label, c_dtype, web_dtype in TCPclient_parameters + RTUclient_parameters:
+        ParamFuncName                      = "__modbus_set_ClientNode_" + name
+        SetClientParamFuncs[name]          = getattr(PLCObject.PLClibraryHandle, ParamFuncName)
+        SetClientParamFuncs[name].restype  = None
+        SetClientParamFuncs[name].argtypes = [ctypes.c_int, c_dtype]
+
+    # XXX TODO : stop reading from PLC .so file. This code is template code
+    #            that can use modbus extension build data
+    for name, web_label, c_dtype, web_dtype in TCPserver_parameters + RTUslave_parameters + General_parameters:
+        ParamFuncName                      = "__modbus_get_ServerNode_" + name        
+        GetServerParamFuncs[name]          = getattr(PLCObject.PLClibraryHandle, ParamFuncName)
+        GetServerParamFuncs[name].restype  = c_dtype
+        GetServerParamFuncs[name].argtypes = [ctypes.c_int]
+        
+    for name, web_label, c_dtype, web_dtype in TCPserver_parameters + RTUslave_parameters:
+        ParamFuncName                      = "__modbus_set_ServerNode_" + name
+        SetServerParamFuncs[name]          = getattr(PLCObject.PLClibraryHandle, ParamFuncName)
+        SetServerParamFuncs[name].restype  = None
+        SetServerParamFuncs[name].argtypes = [ctypes.c_int, c_dtype]
+
+    for node_id in range(client_count):
+        _AddWebNode(node_id, "client" ,GetClientParamFuncs, SetClientParamFuncs)
+
+    for node_id in range(server_count):
+        _AddWebNode(node_id, "server", GetServerParamFuncs, SetServerParamFuncs)
+
+
+
+
+
+def _runtime_0_modbus_websettings_cleanup():
+    """
+    Callback function, called (by PLCObject.py) when a PLC program is unloaded from memory
+    """
+
+    #PLCObject.LogMessage("Modbus web server extension::OnUnLoadPLC() Called...")
+    
+    # Delete the Modbus specific web interface extensions
+    # (Safe to ask to delete, even if it has not been added!)
+    global _WebNodeList
+    for index, WebNode_entry in enumerate(_WebNodeList):
+        config_hash = WebNode_entry["config_hash"]
+        NS.removeExtensionSetting(config_hash)
+        
+    # Dele all entries...
+    _WebNodeList = []
+

Beremiz/beremiz_tutorial_opc_ua/build/generated_plc.st

+FUNCTION_BLOCK CounterST
+  VAR_INPUT
+    Reset : BOOL;
+  END_VAR
+  VAR_OUTPUT
+    Out1 : INT;
+    Out0 : INT;
+  END_VAR
+  VAR
+    Cnt1 : INT;
+    Cnt0 : INT;
+  END_VAR
+  VAR_EXTERNAL
+    ResetCounterValue : INT;
+    Relay0Value : BOOL;
+    Relay1Value : BOOL;
+    Relay2Value : BOOL;
+    Relay3Value : BOOL;
+    Relay3Value0 : DINT;
+  END_VAR
+
+  IF Reset THEN
+    Cnt0 := ResetCounterValue;
+    Cnt1 := ResetCounterValue;
+    Reset := False;
+  ELSE
+    Cnt0 := Cnt0 + 1;
+    Cnt1 := Cnt1 + 1;
+    IF Cnt1 = 100 THEN
+      Relay3Value0 := 1;
+    END_IF;
+    
+    IF Cnt1 = 500 THEN
+      Relay3Value0 := 0;
+    END_IF;
+    
+  END_IF;
+
+  Out1 := Cnt1;
+  Out0 := Cnt0;
+END_FUNCTION_BLOCK
+
+PROGRAM plc_prg
+  VAR_INPUT
+    Reset : BOOL;
+  END_VAR
+  VAR_OUTPUT
+    Cnt0 : INT;
+    Cnt1 : INT;
+  END_VAR
+  VAR
+    CounterST0 : CounterST;
+  END_VAR
+
+  CounterST0(Reset := Reset);
+  Cnt1 := CounterST0.Out1;
+  Cnt0 := CounterST0.Out0;
+END_PROGRAM
+
+
+CONFIGURATION config
+  VAR_GLOBAL
+    ResetCounterValue : INT := 0;
+    Relay0Value AT %QX0.0.0.0 : BOOL := 0;
+    Relay1Value AT %QX0.0.1.1 : BOOL := 0;
+    Relay2Value AT %QX0.0.2.2 : BOOL := 0;
+    Relay3Value AT %QX0.0.3.3 : BOOL := 0;
+    Relay3Value0 AT %QD1.0 : DINT := 0;
+  END_VAR
+
+  RESOURCE resource1 ON PLC
+    TASK task0(INTERVAL := T#20ms,PRIORITY := 0);
+    PROGRAM instance0 WITH task0 : plc_prg;
+  END_RESOURCE
+END_CONFIGURATION

Beremiz/beremiz_tutorial_opc_ua/build/lastbuildPLC.md5

+5ad2334f5cfa95cc9bb7d9400960e0df
\ No newline at end of file

Beremiz/beremiz_tutorial_opc_ua/build/opcua_client__1.c

+/* code generated by beremiz OPC-UA extension */
+
+#include <open62541/client_config_default.h>
+#include <open62541/client_highlevel.h>
+#include <open62541/plugin/log_stdout.h>
+
+UA_Client *client;
+
+#define DECL_VAR(ua_type, C_type, c_loc_name)                                                       \
+UA_Variant *c_loc_name##_variant;                                                                   \
+C_type c_loc_name##_buf = 0;                                                                        \
+C_type *c_loc_name = &c_loc_name##_buf;
+
+
+DECL_VAR(UA_Int32, uint32_t, __ID1_0)
+DECL_VAR(UA_Int32, uint32_t, __ID1_1)
+DECL_VAR(UA_Int32, uint32_t, __ID1_2)
+DECL_VAR(UA_Int32, uint32_t, __ID1_3)
+DECL_VAR(UA_Int32, uint32_t, __QD1_0)
+DECL_VAR(UA_Int32, uint32_t, __QD1_1)
+DECL_VAR(UA_Int32, uint32_t, __QD1_2)
+DECL_VAR(UA_Int32, uint32_t, __QD1_3)
+
+#define FREE_VARIANT(ua_type, c_loc_name)                                                           \
+    UA_Variant_delete(c_loc_name##_variant);
+
+void __cleanup_1(void)
+{
+    UA_Client_disconnect(client);
+    UA_Client_delete(client);
+
+    FREE_VARIANT(UA_Int32, __ID1_0)
+    FREE_VARIANT(UA_Int32, __ID1_1)
+    FREE_VARIANT(UA_Int32, __ID1_2)
+    FREE_VARIANT(UA_Int32, __ID1_3)
+    FREE_VARIANT(UA_Int32, __QD1_0)
+    FREE_VARIANT(UA_Int32, __QD1_1)
+    FREE_VARIANT(UA_Int32, __QD1_2)
+    FREE_VARIANT(UA_Int32, __QD1_3)
+}
+
+
+#define ALLOC_VARIANT(ua_type, c_loc_name)                                                          \
+    c_loc_name##_variant = UA_Variant_new();
+
+int __init_1(int argc,char **argv)
+{
+    UA_StatusCode retval;
+    client = UA_Client_new();
+    UA_ClientConfig_setDefault(UA_Client_getConfig(client));
+
+    ALLOC_VARIANT(UA_Int32, __ID1_0)
+    ALLOC_VARIANT(UA_Int32, __ID1_1)
+    ALLOC_VARIANT(UA_Int32, __ID1_2)
+    ALLOC_VARIANT(UA_Int32, __ID1_3)
+    ALLOC_VARIANT(UA_Int32, __QD1_0)
+    ALLOC_VARIANT(UA_Int32, __QD1_1)
+    ALLOC_VARIANT(UA_Int32, __QD1_2)
+    ALLOC_VARIANT(UA_Int32, __QD1_3)
+
+    /* Connect to server */
+    retval = UA_Client_connect(client, "opc.tcp://192.168.0.78:4840");
+    if(retval != UA_STATUSCODE_GOOD) {
+        UA_Client_delete(client);
+        return EXIT_FAILURE;
+    }
+}
+
+#define READ_VALUE(ua_type, ua_type_enum, c_loc_name, ua_nodeid_type, ua_nsidx, ua_node_id)         \
+    retval = UA_Client_readValueAttribute(                                                          \
+        client, ua_nodeid_type(ua_nsidx, ua_node_id), c_loc_name##_variant);                        \
+    if(retval == UA_STATUSCODE_GOOD && UA_Variant_isScalar(c_loc_name##_variant) &&                 \
+       c_loc_name##_variant->type == &UA_TYPES[ua_type_enum]) {                                     \
+            c_loc_name##_buf = *(ua_type*)c_loc_name##_variant->data;                               \
+    }
+
+void __retrieve_1(void)
+{
+    UA_StatusCode retval;
+
+    READ_VALUE(UA_Int32, UA_TYPES_INT32, __ID1_0, UA_NODEID_STRING, 1, "relay0")
+    READ_VALUE(UA_Int32, UA_TYPES_INT32, __ID1_1, UA_NODEID_STRING, 1, "relay1")
+    READ_VALUE(UA_Int32, UA_TYPES_INT32, __ID1_2, UA_NODEID_STRING, 1, "relay2")
+    READ_VALUE(UA_Int32, UA_TYPES_INT32, __ID1_3, UA_NODEID_STRING, 1, "relay3")
+    READ_VALUE(UA_Int32, UA_TYPES_INT32, __QD1_0, UA_NODEID_STRING, 1, "relay0")
+    READ_VALUE(UA_Int32, UA_TYPES_INT32, __QD1_1, UA_NODEID_STRING, 1, "relay1")
+    READ_VALUE(UA_Int32, UA_TYPES_INT32, __QD1_2, UA_NODEID_STRING, 1, "relay2")
+    READ_VALUE(UA_Int32, UA_TYPES_INT32, __QD1_3, UA_NODEID_STRING, 1, "relay3")
+}
+
+#define WRITE_VALUE(ua_type, ua_type_enum, c_loc_name, ua_nodeid_type, ua_nsidx, ua_node_id)        \
+    UA_Variant_setScalarCopy(c_loc_name##_variant, (ua_type*)c_loc_name, &UA_TYPES[ua_type_enum]);  \
+    UA_Client_writeValueAttribute(client, ua_nodeid_type(ua_nsidx, ua_node_id), c_loc_name##_variant);
+
+void __publish_1(void)
+{
+
+    WRITE_VALUE(UA_Int32, UA_TYPES_INT32, __ID1_0, UA_NODEID_STRING, 1, "relay0")
+    WRITE_VALUE(UA_Int32, UA_TYPES_INT32, __ID1_1, UA_NODEID_STRING, 1, "relay1")
+    WRITE_VALUE(UA_Int32, UA_TYPES_INT32, __ID1_2, UA_NODEID_STRING, 1, "relay2")
+    WRITE_VALUE(UA_Int32, UA_TYPES_INT32, __ID1_3, UA_NODEID_STRING, 1, "relay3")
+    WRITE_VALUE(UA_Int32, UA_TYPES_INT32, __QD1_0, UA_NODEID_STRING, 1, "relay0")
+    WRITE_VALUE(UA_Int32, UA_TYPES_INT32, __QD1_1, UA_NODEID_STRING, 1, "relay1")
+    WRITE_VALUE(UA_Int32, UA_TYPES_INT32, __QD1_2, UA_NODEID_STRING, 1, "relay2")
+    WRITE_VALUE(UA_Int32, UA_TYPES_INT32, __QD1_3, UA_NODEID_STRING, 1, "relay3")
+}
+

Beremiz/beremiz_tutorial_opc_ua/build/plc.st

+TYPE
+  LOGLEVEL : (CRITICAL, WARNING, INFO, DEBUG) := INFO;
+END_TYPE
+
+FUNCTION_BLOCK LOGGER
+  VAR_INPUT
+    TRIG : BOOL;
+    MSG : STRING;
+    LEVEL : LOGLEVEL := INFO;
+  END_VAR
+  VAR
+    TRIG0 : BOOL;
+  END_VAR
+
+  IF TRIG AND NOT TRIG0 THEN
+  {{
+   LogMessage(GetFbVar(LEVEL),(char*)GetFbVar(MSG, .body),GetFbVar(MSG, .len));
+  }}
+  END_IF;
+  TRIG0:=TRIG;
+END_FUNCTION_BLOCK
+
+
+
+FUNCTION_BLOCK python_eval
+  VAR_INPUT
+    TRIG : BOOL;
+    CODE : STRING;
+  END_VAR
+  VAR_OUTPUT
+    ACK : BOOL;
+    RESULT : STRING;
+  END_VAR
+  VAR
+    STATE : DWORD;
+    BUFFER : STRING;
+    PREBUFFER : STRING;
+    TRIGM1 : BOOL;
+    TRIGGED : BOOL;
+  END_VAR
+
+  {extern void __PythonEvalFB(int, PYTHON_EVAL*);__PythonEvalFB(0, data__);}
+END_FUNCTION_BLOCK
+
+FUNCTION_BLOCK python_poll
+  VAR_INPUT
+    TRIG : BOOL;
+    CODE : STRING;
+  END_VAR
+  VAR_OUTPUT
+    ACK : BOOL;
+    RESULT : STRING;
+  END_VAR
+  VAR
+    STATE : DWORD;
+    BUFFER : STRING;
+    PREBUFFER : STRING;
+    TRIGM1 : BOOL;
+    TRIGGED : BOOL;
+  END_VAR
+
+  {extern void __PythonEvalFB(int, PYTHON_EVAL*);__PythonEvalFB(1,(PYTHON_EVAL*)(void*)data__);}
+END_FUNCTION_BLOCK
+
+FUNCTION_BLOCK python_gear
+  VAR_INPUT
+    N : UINT;
+    TRIG : BOOL;
+    CODE : STRING;
+  END_VAR
+  VAR_OUTPUT
+    ACK : BOOL;
+    RESULT : STRING;
+  END_VAR
+  VAR
+    py_eval : python_eval;
+    COUNTER : UINT;
+    _TMP_ADD10_OUT : UINT;
+    _TMP_EQ13_OUT : BOOL;
+    _TMP_SEL15_OUT : UINT;
+    _TMP_AND7_OUT : BOOL;
+  END_VAR
+
+  _TMP_ADD10_OUT := ADD(COUNTER, 1);
+  _TMP_EQ13_OUT := EQ(N, _TMP_ADD10_OUT);
+  _TMP_SEL15_OUT := SEL(_TMP_EQ13_OUT, _TMP_ADD10_OUT, 0);
+  COUNTER := _TMP_SEL15_OUT;
+  _TMP_AND7_OUT := AND(_TMP_EQ13_OUT, TRIG);
+  py_eval(TRIG := _TMP_AND7_OUT, CODE := CODE);
+  ACK := py_eval.ACK;
+  RESULT := py_eval.RESULT;
+END_FUNCTION_BLOCK
+
+
+FUNCTION_BLOCK CounterST
+  VAR_INPUT
+    Reset : BOOL;
+  END_VAR
+  VAR_OUTPUT
+    Out1 : INT;
+    Out0 : INT;
+  END_VAR
+  VAR
+    Cnt1 : INT;
+    Cnt0 : INT;
+  END_VAR
+  VAR_EXTERNAL
+    ResetCounterValue : INT;
+    Relay0Value : BOOL;
+    Relay1Value : BOOL;
+    Relay2Value : BOOL;
+    Relay3Value : BOOL;
+    Relay3Value0 : DINT;
+  END_VAR
+
+  IF Reset THEN
+    Cnt0 := ResetCounterValue;
+    Cnt1 := ResetCounterValue;
+    Reset := False;
+  ELSE
+    Cnt0 := Cnt0 + 1;
+    Cnt1 := Cnt1 + 1;
+    IF Cnt1 = 100 THEN
+      Relay3Value0 := 1;
+    END_IF;
+    
+    IF Cnt1 = 500 THEN
+      Relay3Value0 := 0;
+    END_IF;
+    
+  END_IF;
+
+  Out1 := Cnt1;
+  Out0 := Cnt0;
+END_FUNCTION_BLOCK
+
+PROGRAM plc_prg
+  VAR_INPUT
+    Reset : BOOL;
+  END_VAR
+  VAR_OUTPUT
+    Cnt0 : INT;
+    Cnt1 : INT;
+  END_VAR
+  VAR
+    CounterST0 : CounterST;
+  END_VAR
+
+  CounterST0(Reset := Reset);
+  Cnt1 := CounterST0.Out1;
+  Cnt0 := CounterST0.Out0;
+END_PROGRAM
+
+
+CONFIGURATION config
+  VAR_GLOBAL
+    ResetCounterValue : INT := 0;
+    Relay0Value AT %QX0.0.0.0 : BOOL := 0;
+    Relay1Value AT %QX0.0.1.1 : BOOL := 0;
+    Relay2Value AT %QX0.0.2.2 : BOOL := 0;
+    Relay3Value AT %QX0.0.3.3 : BOOL := 0;
+    Relay3Value0 AT %QD1.0 : DINT := 0;
+  END_VAR
+
+  RESOURCE resource1 ON PLC
+    TASK task0(INTERVAL := T#20ms,PRIORITY := 0);
+    PROGRAM instance0 WITH task0 : plc_prg;
+  END_RESOURCE
+END_CONFIGURATION

Beremiz/beremiz_tutorial_opc_ua/build/plc_debugger.c

+/*
+ * DEBUGGER code
+ * 
+ * On "publish", when buffer is free, debugger stores arbitrary variables 
+ * content into, and mark this buffer as filled
+ * 
+ * 
+ * Buffer content is read asynchronously, (from non real time part), 
+ * and then buffer marked free again.
+ *  
+ * 
+ * */
+#ifdef TARGET_DEBUG_AND_RETAIN_DISABLE
+
+void __init_debug    (void){}
+void __cleanup_debug (void){}
+void __retrieve_debug(void){}
+void __publish_debug (void){}
+
+#else
+
+#include "iec_types_all.h"
+#include "POUS.h"
+/*for memcpy*/
+#include <string.h>
+#include <stdio.h>
+
+#ifndef TARGET_ONLINE_DEBUG_DISABLE
+#define BUFFER_SIZE 36
+
+/* Atomically accessed variable for buffer state */
+#define BUFFER_FREE 0
+#define BUFFER_BUSY 1
+static long buffer_state = BUFFER_FREE;
+
+/* The buffer itself */
+char debug_buffer[BUFFER_SIZE];
+
+/* Buffer's cursor*/
+static char* buffer_cursor = debug_buffer;
+#endif
+
+static unsigned int retain_offset = 0;
+/***
+ * Declare programs 
+ **/
+extern PLC_PRG RESOURCE1__INSTANCE0;
+
+/***
+ * Declare global variables from resources and conf 
+ **/
+extern __IEC_INT_t CONFIG__RESETCOUNTERVALUE;
+extern __IEC_BOOL_p CONFIG__RELAY0VALUE;
+extern __IEC_BOOL_p CONFIG__RELAY1VALUE;
+extern __IEC_BOOL_p CONFIG__RELAY2VALUE;
+extern __IEC_BOOL_p CONFIG__RELAY3VALUE;
+extern __IEC_DINT_p CONFIG__RELAY3VALUE0;
+extern       PLC_PRG   RESOURCE1__INSTANCE0;
+
+typedef const struct {
+    void *ptr;
+    __IEC_types_enum type;
+} dbgvardsc_t;
+
+static dbgvardsc_t dbgvardsc[] = {
+{&(CONFIG__RESETCOUNTERVALUE), INT_ENUM},
+{&(CONFIG__RELAY0VALUE), BOOL_O_ENUM},
+{&(CONFIG__RELAY1VALUE), BOOL_O_ENUM},
+{&(CONFIG__RELAY2VALUE), BOOL_O_ENUM},
+{&(CONFIG__RELAY3VALUE), BOOL_O_ENUM},
+{&(CONFIG__RELAY3VALUE0), DINT_O_ENUM},
+{&(RESOURCE1__INSTANCE0.RESET), BOOL_ENUM},
+{&(RESOURCE1__INSTANCE0.CNT0), INT_ENUM},
+{&(RESOURCE1__INSTANCE0.CNT1), INT_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.EN), BOOL_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.ENO), BOOL_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.RESET), BOOL_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.OUT1), INT_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.OUT0), INT_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.CNT1), INT_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.CNT0), INT_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.RESETCOUNTERVALUE), INT_P_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.RELAY0VALUE), BOOL_P_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.RELAY1VALUE), BOOL_P_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.RELAY2VALUE), BOOL_P_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.RELAY3VALUE), BOOL_P_ENUM},
+{&(RESOURCE1__INSTANCE0.COUNTERST0.RELAY3VALUE0), DINT_P_ENUM}
+};
+
+typedef void(*__for_each_variable_do_fp)(dbgvardsc_t*);
+void __for_each_variable_do(__for_each_variable_do_fp fp)
+{
+    unsigned int i;
+    for(i = 0; i < sizeof(dbgvardsc)/sizeof(dbgvardsc_t); i++){
+        dbgvardsc_t *dsc = &dbgvardsc[i];
+        if(dsc->type != UNKNOWN_ENUM) 
+            (*fp)(dsc);
+    }
+}
+
+#define __Unpack_desc_type dbgvardsc_t
+
+
+#define __Unpack_case_t(TYPENAME) \
+        case TYPENAME##_ENUM :\
+            *flags = ((__IEC_##TYPENAME##_t *)varp)->flags;\
+            forced_value_p = *real_value_p = &((__IEC_##TYPENAME##_t *)varp)->value;\
+            break;
+
+#define __Unpack_case_p(TYPENAME)\
+        case TYPENAME##_O_ENUM :\
+            *flags = __IEC_OUTPUT_FLAG;\
+        case TYPENAME##_P_ENUM :\
+            *flags |= ((__IEC_##TYPENAME##_p *)varp)->flags;\
+            *real_value_p = ((__IEC_##TYPENAME##_p *)varp)->value;\
+            forced_value_p = &((__IEC_##TYPENAME##_p *)varp)->fvalue;\
+            break;
+
+#define __Is_a_string(dsc) (dsc->type == STRING_ENUM)   ||\
+                           (dsc->type == STRING_P_ENUM) ||\
+                           (dsc->type == STRING_O_ENUM)
+
+static void* UnpackVar(__Unpack_desc_type *dsc, void **real_value_p, char *flags)
+{
+    void *varp = dsc->ptr;
+    void *forced_value_p = NULL;
+    *flags = 0;
+    /* find data to copy*/
+    switch(dsc->type){
+        __ANY(__Unpack_case_t)
+        __ANY(__Unpack_case_p)
+    default:
+        break;
+    }
+    if (*flags & __IEC_FORCE_FLAG)
+        return forced_value_p;
+    return *real_value_p;
+}
+
+
+
+void Remind(unsigned int offset, unsigned int count, void * p);
+
+void RemindIterator(dbgvardsc_t *dsc)
+{
+    void *real_value_p = NULL;
+    char flags = 0;
+    UnpackVar(dsc, &real_value_p, &flags);
+
+    if(flags & __IEC_RETAIN_FLAG){
+        USINT size = __get_type_enum_size(dsc->type);
+        /* compute next cursor positon*/
+        unsigned int next_retain_offset = retain_offset + size;
+        /* if buffer not full */
+        Remind(retain_offset, size, real_value_p);
+        /* increment cursor according size*/
+        retain_offset = next_retain_offset;
+    }
+}
+
+extern int CheckRetainBuffer(void);
+extern void InitRetain(void);
+
+void __init_debug(void)
+{
+    /* init local static vars */
+#ifndef TARGET_ONLINE_DEBUG_DISABLE
+    buffer_cursor = debug_buffer;
+    buffer_state = BUFFER_FREE;
+#endif
+
+    retain_offset = 0;
+    InitRetain();
+    /* Iterate over all variables to fill debug buffer */
+    if(CheckRetainBuffer()){
+        __for_each_variable_do(RemindIterator);
+    }else{
+        char mstr[] = "RETAIN memory invalid - defaults used";
+        LogMessage(LOG_WARNING, mstr, sizeof(mstr));
+    }
+    retain_offset = 0;
+}
+
+extern void InitiateDebugTransfer(void);
+extern void CleanupRetain(void);
+
+extern unsigned long __tick;
+
+void __cleanup_debug(void)
+{
+#ifndef TARGET_ONLINE_DEBUG_DISABLE
+    buffer_cursor = debug_buffer;
+    InitiateDebugTransfer();
+#endif    
+
+    CleanupRetain();
+}
+
+void __retrieve_debug(void)
+{
+}
+
+
+void Retain(unsigned int offset, unsigned int count, void * p);
+
+static inline void BufferIterator(dbgvardsc_t *dsc, int do_debug)
+{
+    void *real_value_p = NULL;
+    void *visible_value_p = NULL;
+    char flags = 0;
+
+    visible_value_p = UnpackVar(dsc, &real_value_p, &flags);
+
+    if(flags & ( __IEC_DEBUG_FLAG | __IEC_RETAIN_FLAG)){
+        USINT size = __get_type_enum_size(dsc->type);
+
+#ifndef TARGET_ONLINE_DEBUG_DISABLE
+        if(flags & __IEC_DEBUG_FLAG){
+            /* copy visible variable to buffer */;
+            if(do_debug){
+                /* compute next cursor positon.
+                   No need to check overflow, as BUFFER_SIZE
+                   is computed large enough */
+                if(__Is_a_string(dsc)){
+                    /* optimization for strings */
+                    size = ((STRING*)visible_value_p)->len + 1;
+                }
+                char* next_cursor = buffer_cursor + size;
+                /* copy data to the buffer */
+                memcpy(buffer_cursor, visible_value_p, size);
+                /* increment cursor according size*/
+                buffer_cursor = next_cursor;
+            }
+            /* re-force real value of outputs (M and Q)*/
+            if((flags & __IEC_FORCE_FLAG) && (flags & __IEC_OUTPUT_FLAG)){
+                memcpy(real_value_p, visible_value_p, size);
+            }
+        }
+#endif
+
+        if(flags & __IEC_RETAIN_FLAG){
+            /* compute next cursor positon*/
+            unsigned int next_retain_offset = retain_offset + size;
+            /* if buffer not full */
+            Retain(retain_offset, size, real_value_p);
+            /* increment cursor according size*/
+            retain_offset = next_retain_offset;
+        }
+    }
+}
+
+void DebugIterator(dbgvardsc_t *dsc){
+    BufferIterator(dsc, 1);
+}
+
+void RetainIterator(dbgvardsc_t *dsc){
+    BufferIterator(dsc, 0);
+}
+
+
+unsigned int retain_size = 0;
+
+/* GetRetainSizeIterator */
+void GetRetainSizeIterator(dbgvardsc_t *dsc)
+{
+    void *real_value_p = NULL;
+    char flags = 0;
+    UnpackVar(dsc, &real_value_p, &flags);
+
+    if(flags & __IEC_RETAIN_FLAG){
+        USINT size = __get_type_enum_size(dsc->type);
+        /* Calc retain buffer size */
+        retain_size += size;
+    }
+}
+
+/* Return size of all retain variables */
+unsigned int GetRetainSize(void)
+{
+    __for_each_variable_do(GetRetainSizeIterator);
+    return retain_size;
+}
+
+
+extern void PLC_GetTime(IEC_TIME*);
+extern int TryEnterDebugSection(void);
+extern long AtomicCompareExchange(long*, long, long);
+extern long long AtomicCompareExchange64(long long* , long long , long long);
+extern void LeaveDebugSection(void);
+extern void ValidateRetainBuffer(void);
+extern void InValidateRetainBuffer(void);
+
+void __publish_debug(void)
+{
+    retain_offset = 0;
+    InValidateRetainBuffer();
+    
+#ifndef TARGET_ONLINE_DEBUG_DISABLE 
+    /* Check there is no running debugger re-configuration */
+    if(TryEnterDebugSection()){
+        /* Lock buffer */
+        long latest_state = AtomicCompareExchange(
+            &buffer_state,
+            BUFFER_FREE,
+            BUFFER_BUSY);
+            
+        /* If buffer was free */
+        if(latest_state == BUFFER_FREE)
+        {
+            /* Reset buffer cursor */
+            buffer_cursor = debug_buffer;
+            /* Iterate over all variables to fill debug buffer */
+            __for_each_variable_do(DebugIterator);
+            
+            /* Leave debug section,
+             * Trigger asynchronous transmission 
+             * (returns immediately) */
+            InitiateDebugTransfer(); /* size */
+        }else{
+            /* when not debugging, do only retain */
+            __for_each_variable_do(RetainIterator);
+        }
+        LeaveDebugSection();
+    }else
+#endif
+    {
+        /* when not debugging, do only retain */
+        __for_each_variable_do(RetainIterator);
+    }
+    ValidateRetainBuffer();
+}
+
+#ifndef TARGET_ONLINE_DEBUG_DISABLE
+#define __RegisterDebugVariable_case_t(TYPENAME) \
+        case TYPENAME##_ENUM :\
+            ((__IEC_##TYPENAME##_t *)varp)->flags |= flags;\
+            if(force)\
+             ((__IEC_##TYPENAME##_t *)varp)->value = *((TYPENAME *)force);\
+            break;
+#define __RegisterDebugVariable_case_p(TYPENAME)\
+        case TYPENAME##_P_ENUM :\
+            ((__IEC_##TYPENAME##_p *)varp)->flags |= flags;\
+            if(force)\
+             ((__IEC_##TYPENAME##_p *)varp)->fvalue = *((TYPENAME *)force);\
+            break;\
+        case TYPENAME##_O_ENUM :\
+            ((__IEC_##TYPENAME##_p *)varp)->flags |= flags;\
+            if(force){\
+             ((__IEC_##TYPENAME##_p *)varp)->fvalue = *((TYPENAME *)force);\
+             *(((__IEC_##TYPENAME##_p *)varp)->value) = *((TYPENAME *)force);\
+            }\
+            break;
+void RegisterDebugVariable(unsigned int idx, void* force)
+{
+    if(idx  < sizeof(dbgvardsc)/sizeof(dbgvardsc_t)){
+        unsigned char flags = force ?
+            __IEC_DEBUG_FLAG | __IEC_FORCE_FLAG :
+            __IEC_DEBUG_FLAG;
+        dbgvardsc_t *dsc = &dbgvardsc[idx];
+        void *varp = dsc->ptr;
+        switch(dsc->type){
+            __ANY(__RegisterDebugVariable_case_t)
+            __ANY(__RegisterDebugVariable_case_p)
+        default:
+            break;
+        }
+    }
+}
+
+#define __ResetDebugVariablesIterator_case_t(TYPENAME) \
+        case TYPENAME##_ENUM :\
+            ((__IEC_##TYPENAME##_t *)varp)->flags &= ~(__IEC_DEBUG_FLAG|__IEC_FORCE_FLAG);\
+            break;
+
+#define __ResetDebugVariablesIterator_case_p(TYPENAME)\
+        case TYPENAME##_P_ENUM :\
+        case TYPENAME##_O_ENUM :\
+            ((__IEC_##TYPENAME##_p *)varp)->flags &= ~(__IEC_DEBUG_FLAG|__IEC_FORCE_FLAG);\
+            break;
+
+void ResetDebugVariablesIterator(dbgvardsc_t *dsc)
+{
+    /* force debug flag to 0*/
+    void *varp = dsc->ptr;
+    switch(dsc->type){
+        __ANY(__ResetDebugVariablesIterator_case_t)
+        __ANY(__ResetDebugVariablesIterator_case_p)
+    default:
+        break;
+    }
+}
+
+void ResetDebugVariables(void)
+{
+    __for_each_variable_do(ResetDebugVariablesIterator);
+}
+
+void FreeDebugData(void)
+{
+    /* atomically mark buffer as free */
+    AtomicCompareExchange(
+        &buffer_state,
+        BUFFER_BUSY,
+        BUFFER_FREE);
+}
+int WaitDebugData(unsigned long *tick);
+/* Wait until debug data ready and return pointer to it */
+int GetDebugData(unsigned long *tick, unsigned long *size, void **buffer){
+    int wait_error = WaitDebugData(tick);
+    if(!wait_error){
+        *size = buffer_cursor - debug_buffer;
+        *buffer = debug_buffer;
+    }
+    return wait_error;
+}
+#endif
+#endif
+

Beremiz/beremiz_tutorial_opc_ua/build/plc_main.c

+/**
+ * Head of code common to all C targets
+ **/
+
+#include "beremiz.h"
+#include <string.h>
+/*
+ * Prototypes of functions provided by generated C softPLC
+ **/
+void config_run__(unsigned long tick);
+void config_init__(void);
+
+/*
+ * Prototypes of functions provided by generated target C code
+ * */
+long long AtomicCompareExchange64(long long*, long long, long long);
+void __init_debug(void);
+void __cleanup_debug(void);
+/*void __retrieve_debug(void);*/
+void __publish_debug(void);
+
+/*
+ *  Variables used by generated C softPLC and plugins
+ **/
+IEC_TIME __CURRENT_TIME;
+IEC_BOOL __DEBUG = 0;
+unsigned long __tick = 0;
+char *PLC_ID = NULL;
+
+/*
+ *  Variable generated by C softPLC and plugins
+ **/
+extern unsigned long greatest_tick_count__;
+
+/* Help to quit cleanly when init fail at a certain level */
+static int init_level = 0;
+
+/*
+ * Prototypes of functions exported by plugins
+ **/
+int __init_py_ext(int argc,char **argv);
+void __cleanup_py_ext(void);
+void __retrieve_py_ext(void);
+void __publish_py_ext(void);
+int __init_0(int argc,char **argv);
+void __cleanup_0(void);
+void __retrieve_0(void);
+void __publish_0(void);
+int __init_1(int argc,char **argv);
+void __cleanup_1(void);
+void __retrieve_1(void);
+void __publish_1(void);
+
+/*
+ * Retrieve input variables, run PLC and publish output variables
+ **/
+void __run(void)
+{
+    __tick++;
+    if (greatest_tick_count__)
+        __tick %= greatest_tick_count__;
+
+    __retrieve_py_ext();
+    __retrieve_0();
+    __retrieve_1();
+
+    /*__retrieve_debug();*/
+
+    config_run__(__tick);
+
+    __publish_debug();
+
+    __publish_1();
+    __publish_0();
+    __publish_py_ext();
+
+}
+
+/*
+ * Initialize variables according to PLC's default values,
+ * and then init plugins with that values
+ **/
+int __init(int argc,char **argv)
+{
+    int res = 0;
+    init_level = 0;
+    
+    /* Effective tick time with 1ms default value */
+    if(!common_ticktime__)
+        common_ticktime__ = 1000000;
+
+    config_init__();
+    __init_debug();
+    init_level=1; if((res = __init_py_ext(argc,argv))){return res;}
+    init_level=2; if((res = __init_0(argc,argv))){return res;}
+    init_level=3; if((res = __init_1(argc,argv))){return res;}
+    return res;
+}
+/*
+ * Calls plugin cleanup proc.
+ **/
+void __cleanup(void)
+{
+    if(init_level >= 3) __cleanup_1();
+    if(init_level >= 2) __cleanup_0();
+    if(init_level >= 1) __cleanup_py_ext();
+    __cleanup_debug();
+}
+
+void PLC_GetTime(IEC_TIME *CURRENT_TIME);
+void PLC_SetTimer(unsigned long long next, unsigned long long period);
+
+
+
+/**
+ * Linux specific code
+ **/
+
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <locale.h>
+#include <semaphore.h>
+
+static sem_t Run_PLC;
+
+long AtomicCompareExchange(long* atomicvar,long compared, long exchange)
+{
+    return __sync_val_compare_and_swap(atomicvar, compared, exchange);
+}
+long long AtomicCompareExchange64(long long* atomicvar, long long compared, long long exchange)
+{
+    return __sync_val_compare_and_swap(atomicvar, compared, exchange);
+}
+
+void PLC_GetTime(IEC_TIME *CURRENT_TIME)
+{
+    struct timespec tmp;
+    clock_gettime(CLOCK_REALTIME, &tmp);
+    CURRENT_TIME->tv_sec = tmp.tv_sec;
+    CURRENT_TIME->tv_nsec = tmp.tv_nsec;
+}
+
+void PLC_timer_notify(sigval_t val)
+{
+    PLC_GetTime(&__CURRENT_TIME);
+    sem_post(&Run_PLC);
+}
+
+timer_t PLC_timer;
+
+void PLC_SetTimer(unsigned long long next, unsigned long long period)
+{
+    struct itimerspec timerValues;
+	/*
+	printf("SetTimer(%lld,%lld)\n",next, period);
+	*/
+    memset (&timerValues, 0, sizeof (struct itimerspec));
+	{
+#ifdef __lldiv_t_defined
+		lldiv_t nxt_div = lldiv(next, 1000000000);
+		lldiv_t period_div = lldiv(period, 1000000000);
+	    timerValues.it_value.tv_sec = nxt_div.quot;
+	    timerValues.it_value.tv_nsec = nxt_div.rem;
+	    timerValues.it_interval.tv_sec = period_div.quot;
+	    timerValues.it_interval.tv_nsec = period_div.rem;
+#else
+	    timerValues.it_value.tv_sec = next / 1000000000;
+	    timerValues.it_value.tv_nsec = next % 1000000000;
+	    timerValues.it_interval.tv_sec = period / 1000000000;
+	    timerValues.it_interval.tv_nsec = period % 1000000000;
+#endif
+	}
+    timer_settime (PLC_timer, 0, &timerValues, NULL);
+}
+//
+void catch_signal(int sig)
+{
+//  signal(SIGTERM, catch_signal);
+  signal(SIGINT, catch_signal);
+  printf("Got Signal %d\n",sig);
+  exit(0);
+}
+
+
+static unsigned long __debug_tick;
+
+pthread_t PLC_thread;
+static pthread_mutex_t python_wait_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t python_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t debug_wait_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t debug_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+int PLC_shutdown = 0;
+
+int ForceSaveRetainReq(void) {
+    return PLC_shutdown;
+}
+
+void PLC_thread_proc(void *arg)
+{
+    while (!PLC_shutdown) {
+        sem_wait(&Run_PLC);
+        __run();
+    }
+    pthread_exit(0);
+}
+
+#define maxval(a,b) ((a>b)?a:b)
+int startPLC(int argc,char **argv)
+{
+    struct sigevent sigev;
+    setlocale(LC_NUMERIC, "C");
+
+    PLC_shutdown = 0;
+
+    sem_init(&Run_PLC, 0, 0);
+
+    pthread_create(&PLC_thread, NULL, (void*) &PLC_thread_proc, NULL);
+
+    memset (&sigev, 0, sizeof (struct sigevent));
+    sigev.sigev_value.sival_int = 0;
+    sigev.sigev_notify = SIGEV_THREAD;
+    sigev.sigev_notify_attributes = NULL;
+    sigev.sigev_notify_function = PLC_timer_notify;
+
+    pthread_mutex_init(&debug_wait_mutex, NULL);
+    pthread_mutex_init(&debug_mutex, NULL);
+    pthread_mutex_init(&python_wait_mutex, NULL);
+    pthread_mutex_init(&python_mutex, NULL);
+
+    pthread_mutex_lock(&debug_wait_mutex);
+    pthread_mutex_lock(&python_wait_mutex);
+
+    timer_create (CLOCK_MONOTONIC, &sigev, &PLC_timer);
+    if(  __init(argc,argv) == 0 ){
+        PLC_SetTimer(common_ticktime__,common_ticktime__);
+
+        /* install signal handler for manual break */
+        signal(SIGINT, catch_signal);
+    }else{
+        return 1;
+    }
+    return 0;
+}
+
+int TryEnterDebugSection(void)
+{
+    if (pthread_mutex_trylock(&debug_mutex) == 0){
+        /* Only enter if debug active */
+        if(__DEBUG){
+            return 1;
+        }
+        pthread_mutex_unlock(&debug_mutex);
+    }
+    return 0;
+}
+
+void LeaveDebugSection(void)
+{
+    pthread_mutex_unlock(&debug_mutex);
+}
+
+int stopPLC()
+{
+    /* Stop the PLC */
+    PLC_shutdown = 1;
+    sem_post(&Run_PLC);
+    PLC_SetTimer(0,0);
+	pthread_join(PLC_thread, NULL);
+	sem_destroy(&Run_PLC);
+    timer_delete (PLC_timer);
+    __cleanup();
+    pthread_mutex_destroy(&debug_wait_mutex);
+    pthread_mutex_destroy(&debug_mutex);
+    pthread_mutex_destroy(&python_wait_mutex);
+    pthread_mutex_destroy(&python_mutex);
+    return 0;
+}
+
+extern unsigned long __tick;
+
+int WaitDebugData(unsigned long *tick)
+{
+    int res;
+    if (PLC_shutdown) return 1;
+    /* Wait signal from PLC thread */
+    res = pthread_mutex_lock(&debug_wait_mutex);
+    *tick = __debug_tick;
+    return res;
+}
+
+/* Called by PLC thread when debug_publish finished
+ * This is supposed to unlock debugger thread in WaitDebugData*/
+void InitiateDebugTransfer()
+{
+    /* remember tick */
+    __debug_tick = __tick;
+    /* signal debugger thread it can read data */
+    pthread_mutex_unlock(&debug_wait_mutex);
+}
+
+int suspendDebug(int disable)
+{
+    /* Prevent PLC to enter debug code */
+    pthread_mutex_lock(&debug_mutex);
+    /*__DEBUG is protected by this mutex */
+    __DEBUG = !disable;
+    if (disable)
+    	pthread_mutex_unlock(&debug_mutex);
+    return 0;
+}
+
+void resumeDebug(void)
+{
+    __DEBUG = 1;
+    /* Let PLC enter debug code */
+    pthread_mutex_unlock(&debug_mutex);
+}
+
+/* from plc_python.c */
+int WaitPythonCommands(void)
+{
+    /* Wait signal from PLC thread */
+    return pthread_mutex_lock(&python_wait_mutex);
+}
+
+/* Called by PLC thread on each new python command*/
+void UnBlockPythonCommands(void)
+{
+    /* signal debugger thread it can read data */
+    pthread_mutex_unlock(&python_wait_mutex);
+}
+
+int TryLockPython(void)
+{
+    return pthread_mutex_trylock(&python_mutex) == 0;
+}
+
+void UnLockPython(void)
+{
+    pthread_mutex_unlock(&python_mutex);
+}
+
+void LockPython(void)
+{
+    pthread_mutex_lock(&python_mutex);
+}
+
+struct RT_to_nRT_signal_s {
+    pthread_cond_t WakeCond;
+    pthread_mutex_t WakeCondLock;
+};
+
+typedef struct RT_to_nRT_signal_s RT_to_nRT_signal_t;
+
+#define _LogAndReturnNull(text) \
+    {\
+    	char mstr[256] = text " for ";\
+        strncat(mstr, name, 255);\
+        LogMessage(LOG_CRITICAL, mstr, strlen(mstr));\
+        return NULL;\
+    }
+
+void *create_RT_to_nRT_signal(char* name){
+    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t*)malloc(sizeof(RT_to_nRT_signal_t));
+
+    if(!sig) 
+    	_LogAndReturnNull("Failed allocating memory for RT_to_nRT signal");
+
+    pthread_cond_init(&sig->WakeCond, NULL);
+    pthread_mutex_init(&sig->WakeCondLock, NULL);
+
+    return (void*)sig;
+}
+
+void delete_RT_to_nRT_signal(void* handle){
+    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t*)handle;
+
+    pthread_cond_destroy(&sig->WakeCond);
+    pthread_mutex_destroy(&sig->WakeCondLock);
+
+    free(sig);
+}
+
+int wait_RT_to_nRT_signal(void* handle){
+    int ret;
+    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t*)handle;
+    pthread_mutex_lock(&sig->WakeCondLock);
+    ret = pthread_cond_wait(&sig->WakeCond, &sig->WakeCondLock);
+    pthread_mutex_unlock(&sig->WakeCondLock);
+    return ret;
+}
+
+int unblock_RT_to_nRT_signal(void* handle){
+    RT_to_nRT_signal_t *sig = (RT_to_nRT_signal_t*)handle;
+    return pthread_cond_signal(&sig->WakeCond);
+}
+
+void nRT_reschedule(void){
+    sched_yield();
+}
+
+/*
+  This file is part of Beremiz, a Integrated Development Environment for
+  programming IEC 61131-3 automates supporting plcopen standard and CanFestival.
+
+  See COPYING.runtime
+
+  Copyright (C) 2018: Sergey Surkov <surkov.sv@summatechnology.ru>
+  Copyright (C) 2018: Andrey Skvortsov <andrej.skvortzov@gmail.com>
+
+*/
+
+#ifndef HAVE_RETAIN
+#include <stdio.h>
+#include <stdint.h>
+#include <unistd.h>
+#include "iec_types.h"
+
+int GetRetainSize(void);
+
+/* Retain buffer.  */
+FILE *retain_buffer;
+const char rb_file[]      = "retain_buffer_file";
+const char rb_file_bckp[] = "retain_buffer_file.bak";
+
+
+/* Retain header struct.  */
+struct retain_info_t {
+	uint32_t retain_size;
+	uint32_t hash_size;
+	uint8_t* hash;
+	uint32_t header_offset;
+	uint32_t header_crc;
+};
+
+/* Init retain info structure.  */
+struct retain_info_t retain_info;
+
+/* CRC lookup table and initial state.  */
+static const uint32_t crc32_table[256] = {
+	0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
+	0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
+	0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
+	0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
+	0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
+	0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
+	0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
+	0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924, 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
+	0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
+	0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
+	0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
+	0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
+	0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
+	0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
+	0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
+	0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
+	0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
+	0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
+	0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
+	0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
+	0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
+	0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
+	0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236, 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
+	0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
+	0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
+	0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
+	0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
+	0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
+	0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
+	0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
+	0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
+	0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D,
+};
+uint32_t retain_crc;
+
+
+/* Calculate CRC32 for len bytes from pointer buf with init starting value.  */
+uint32_t GenerateCRC32Sum(const void* buf, unsigned int len, uint32_t init)
+{
+	uint32_t crc = ~init;
+	unsigned char* current = (unsigned char*) buf;
+	while (len--)
+		crc = crc32_table[(crc ^ *current++) & 0xFF] ^ (crc >> 8);
+	return ~crc;
+}
+
+/* Calc CRC32 for retain file byte by byte.  */
+int CheckFileCRC(FILE* file_buffer)
+{
+	/* Set the magic constant for one-pass CRC calc according to ZIP CRC32.  */
+	const uint32_t magic_number = 0x2144df1c;
+
+	/* CRC initial state.  */
+	uint32_t calc_crc32 = 0;
+	char data_block = 0;
+
+	while(!feof(file_buffer)){
+		if (fread(&data_block, sizeof(data_block), 1, file_buffer))
+			calc_crc32 = GenerateCRC32Sum(&data_block, sizeof(char), calc_crc32);
+	}
+
+	/* Compare crc result with a magic number.  */
+	return (calc_crc32 == magic_number) ? 1 : 0;
+}
+
+/* Compare current hash with hash from file byte by byte.  */
+int CheckFilehash(void)
+{
+	int k,ret;
+	int offset = sizeof(retain_info.retain_size);
+
+	rewind(retain_buffer);
+	fseek(retain_buffer, offset , SEEK_SET);
+
+	uint32_t size;
+	ret = fread(&size, sizeof(size), 1, retain_buffer);
+	if (size != retain_info.hash_size)
+		return 0;
+
+	for(k = 0; k < retain_info.hash_size; k++){
+		uint8_t file_digit;
+		ret = fread(&file_digit, sizeof(char), 1, retain_buffer);
+		if (file_digit != *(retain_info.hash+k))
+			return 0;
+	}
+
+	return 1;
+}
+
+void InitRetain(void)
+{
+	int i;
+
+	/* Get retain size in bytes */
+	retain_info.retain_size = GetRetainSize();
+
+	/* Hash stored in retain file as array of char in hex digits
+	   (that's why we divide strlen in two).  */
+	retain_info.hash_size = PLC_ID ? strlen(PLC_ID)/2 : 0;
+	//retain_info.hash_size = 0;
+	retain_info.hash = malloc(retain_info.hash_size);
+
+	/* Transform hash string into byte sequence.  */
+	for (i = 0; i < retain_info.hash_size; i++) {
+		int byte = 0;
+		sscanf((PLC_ID + i*2), "%02X", &byte);
+		retain_info.hash[i] = byte;
+	}
+
+	/* Calc header offset.  */
+	retain_info.header_offset = sizeof(retain_info.retain_size) + \
+		sizeof(retain_info.hash_size) + \
+		retain_info.hash_size;
+
+	/*  Set header CRC initial state.  */
+	retain_info.header_crc = 0;
+
+	/* Calc crc for header.  */
+	retain_info.header_crc = GenerateCRC32Sum(
+		&retain_info.retain_size,
+		sizeof(retain_info.retain_size),
+		retain_info.header_crc);
+
+	retain_info.header_crc = GenerateCRC32Sum(
+		&retain_info.hash_size,
+		sizeof(retain_info.hash_size),
+		retain_info.header_crc);
+
+	retain_info.header_crc = GenerateCRC32Sum(
+		retain_info.hash,
+		retain_info.hash_size,
+		retain_info.header_crc);
+}
+
+void CleanupRetain(void)
+{
+	/* Free hash memory.  */
+	free(retain_info.hash);
+}
+
+int CheckRetainFile(const char * file)
+{
+	retain_buffer = fopen(file, "rb");
+	if (retain_buffer) {
+		/* Check CRC32 and hash.  */
+		if (CheckFileCRC(retain_buffer))
+			if (CheckFilehash())
+				return 1;
+		fclose(retain_buffer);
+		retain_buffer = NULL;
+	}
+	return 0;
+}
+
+int CheckRetainBuffer(void)
+{
+	retain_buffer = NULL;
+	if (!retain_info.retain_size)
+		return 1;
+
+	/* Check latest retain file.  */
+	if (CheckRetainFile(rb_file))
+		return 1;
+
+	/* Check if we have backup.  */
+	if (CheckRetainFile(rb_file_bckp))
+		return 1;
+
+	/* We don't have any valid retain buffer - nothing to remind.  */
+	return 0;
+}
+
+#ifndef FILE_RETAIN_SAVE_PERIOD_S
+#define FILE_RETAIN_SAVE_PERIOD_S 1.0
+#endif
+
+static double CalcDiffSeconds(IEC_TIME* t1, IEC_TIME *t2)
+{
+	IEC_TIME dt ={
+		t1->tv_sec  - t2->tv_sec,
+		t1->tv_nsec - t2->tv_nsec
+	};
+
+	if ((dt.tv_nsec < -1000000000) || ((dt.tv_sec > 0) && (dt.tv_nsec < 0))){
+		dt.tv_sec--;
+		dt.tv_nsec += 1000000000;
+	}
+	if ((dt.tv_nsec > +1000000000) || ((dt.tv_sec < 0) && (dt.tv_nsec > 0))){
+		dt.tv_sec++;
+		dt.tv_nsec -= 1000000000;
+	}
+	return dt.tv_sec + 1e-9*dt.tv_nsec;
+}
+
+
+int RetainSaveNeeded(void)
+{
+	int ret = 0;
+	static IEC_TIME last_save;
+	IEC_TIME now;
+	double diff_s;
+
+	/* no retain */
+	if (!retain_info.retain_size)
+		return 0;
+
+	/* periodic retain flush to avoid high I/O load */
+	PLC_GetTime(&now);
+
+	diff_s = CalcDiffSeconds(&now, &last_save);
+
+	if ((diff_s > FILE_RETAIN_SAVE_PERIOD_S) || ForceSaveRetainReq()) {
+		ret = 1;
+		last_save = now;
+	}
+	return ret;
+}
+
+void ValidateRetainBuffer(void)
+{
+	if (!retain_buffer)
+		return;
+
+	/* Add retain data CRC to the end of buffer file.  */
+	fseek(retain_buffer, 0, SEEK_END);
+	fwrite(&retain_crc, sizeof(uint32_t), 1, retain_buffer);
+
+	/* Sync file buffer and close file.  */
+#ifdef __WIN32
+	fflush(retain_buffer);
+#else
+	fsync(fileno(retain_buffer));
+#endif
+
+	fclose(retain_buffer);
+	retain_buffer = NULL;
+}
+
+void InValidateRetainBuffer(void)
+{
+	if (!RetainSaveNeeded())
+		return;
+
+	/* Rename old retain file into *.bak if it exists.  */
+	rename(rb_file, rb_file_bckp);
+
+	/* Set file CRC initial value.  */
+	retain_crc = retain_info.header_crc;
+
+	/* Create new retain file.  */
+	retain_buffer = fopen(rb_file, "wb+");
+	if (!retain_buffer) {
+		fprintf(stderr, "Failed to create retain file : %s\n", rb_file);
+		return;
+	}
+
+	/* Write header to the new file.  */
+	fwrite(&retain_info.retain_size,
+		sizeof(retain_info.retain_size), 1, retain_buffer);
+	fwrite(&retain_info.hash_size,
+		sizeof(retain_info.hash_size),   1, retain_buffer);
+	fwrite(retain_info.hash ,
+		sizeof(char), retain_info.hash_size, retain_buffer);
+}
+
+void Retain(unsigned int offset, unsigned int count, void *p)
+{
+	if (!retain_buffer)
+		return;
+
+	/* Generate CRC 32 for each data block.  */
+	retain_crc = GenerateCRC32Sum(p, count, retain_crc);
+
+	/* Save current var in file.  */
+	fseek(retain_buffer, retain_info.header_offset+offset, SEEK_SET);
+	fwrite(p, count, 1, retain_buffer);
+}
+
+void Remind(unsigned int offset, unsigned int count, void *p)
+{
+    int ret;
+	/* Remind variable from file.  */
+	fseek(retain_buffer, retain_info.header_offset+offset, SEEK_SET);
+	ret = fread((void *)p, count, 1, retain_buffer);
+}
+#endif // !HAVE_RETAIN
+/**
+ * Tail of code common to all C targets
+ **/
+
+/** 
+ * LOGGING
+ **/
+#ifndef TARGET_LOGGING_DISABLE
+
+#ifndef LOG_BUFFER_SIZE
+#define LOG_BUFFER_SIZE (1<<14) /*16Ko*/
+#endif
+#ifndef LOG_BUFFER_ATTRS
+#define LOG_BUFFER_ATTRS
+#endif
+
+#define LOG_BUFFER_MASK (LOG_BUFFER_SIZE-1)
+
+static char LogBuff[LOG_LEVELS][LOG_BUFFER_SIZE] LOG_BUFFER_ATTRS;
+static void inline copy_to_log(uint8_t level, uint32_t buffpos, void* buf, uint32_t size){
+    if(buffpos + size < LOG_BUFFER_SIZE){
+        memcpy(&LogBuff[level][buffpos], buf, size);
+    }else{
+        uint32_t remaining = LOG_BUFFER_SIZE - buffpos; 
+        memcpy(&LogBuff[level][buffpos], buf, remaining);
+        memcpy(LogBuff[level], (char*)buf + remaining, size - remaining);
+    }
+}
+static void inline copy_from_log(uint8_t level, uint32_t buffpos, void* buf, uint32_t size){
+    if(buffpos + size < LOG_BUFFER_SIZE){
+        memcpy(buf, &LogBuff[level][buffpos], size);
+    }else{
+        uint32_t remaining = LOG_BUFFER_SIZE - buffpos; 
+        memcpy(buf, &LogBuff[level][buffpos], remaining);
+        memcpy((char*)buf + remaining, LogBuff[level], size - remaining);
+    }
+}
+
+/* Log buffer structure
+
+ |<-Tail1.msgsize->|<-sizeof(mTail)->|<--Tail2.msgsize-->|<-sizeof(mTail)->|...
+ |  Message1 Body  |      Tail1      |   Message2 Body   |      Tail2      |
+
+*/
+typedef struct {
+    uint32_t msgidx;
+    uint32_t msgsize;
+    unsigned long tick;
+    IEC_TIME time;
+} mTail;
+
+/* Log cursor : 64b
+   |63 ... 32|31 ... 0|
+   | Message | Buffer |
+   | counter | Index  | */
+static uint64_t LogCursor[LOG_LEVELS] LOG_BUFFER_ATTRS = {0x0,0x0,0x0,0x0};
+
+void ResetLogCount(void) {
+	uint8_t level;
+	for(level=0;level<LOG_LEVELS;level++){
+		LogCursor[level] = 0;
+	}
+}
+
+/* Store one log message of give size */
+int LogMessage(uint8_t level, char* buf, uint32_t size){
+    if(size < LOG_BUFFER_SIZE - sizeof(mTail)){
+        uint32_t buffpos;
+        uint64_t new_cursor, old_cursor;
+
+        mTail tail;
+        tail.msgsize = size;
+        tail.tick = __tick;
+        PLC_GetTime(&tail.time);
+
+        /* We cannot increment both msg index and string pointer 
+           in a single atomic operation but we can detect having been interrupted.
+           So we can try with atomic compare and swap in a loop until operation
+           succeeds non interrupted */
+        do{
+            old_cursor = LogCursor[level];
+            buffpos = (uint32_t)old_cursor;
+            tail.msgidx = (old_cursor >> 32); 
+            new_cursor = ((uint64_t)(tail.msgidx + 1)<<32) 
+                         | (uint64_t)((buffpos + size + sizeof(mTail)) & LOG_BUFFER_MASK);
+        }while(AtomicCompareExchange64(
+            (long long*)&LogCursor[level],
+            (long long)old_cursor,
+            (long long)new_cursor)!=(long long)old_cursor);
+
+        copy_to_log(level, buffpos, buf, size);
+        copy_to_log(level, (buffpos + size) & LOG_BUFFER_MASK, &tail, sizeof(mTail));
+
+        return 1; /* Success */
+    }else{
+    	char mstr[] = "Logging error : message too big";
+        LogMessage(LOG_CRITICAL, mstr, sizeof(mstr));
+    }
+    return 0;
+}
+
+uint32_t GetLogCount(uint8_t level){
+    return (uint64_t)LogCursor[level] >> 32;
+}
+
+/* Return message size and content */
+uint32_t GetLogMessage(uint8_t level, uint32_t msgidx, char* buf, uint32_t max_size, uint32_t* tick, uint32_t* tv_sec, uint32_t* tv_nsec){
+    uint64_t cursor = LogCursor[level];
+    if(cursor){
+        /* seach cursor */
+        uint32_t stailpos = (uint32_t)cursor; 
+        uint32_t smsgidx;
+        mTail tail;
+        tail.msgidx = cursor >> 32;
+        tail.msgsize = 0;
+
+        /* Message search loop */
+        do {
+            smsgidx = tail.msgidx;
+            stailpos = (stailpos - sizeof(mTail) - tail.msgsize ) & LOG_BUFFER_MASK;
+            copy_from_log(level, stailpos, &tail, sizeof(mTail));
+        }while((tail.msgidx == smsgidx - 1) && (tail.msgidx > msgidx));
+
+        if(tail.msgidx == msgidx){
+            uint32_t sbuffpos = (stailpos - tail.msgsize ) & LOG_BUFFER_MASK; 
+            uint32_t totalsize = tail.msgsize;
+            *tick = tail.tick; 
+            *tv_sec = tail.time.tv_sec; 
+            *tv_nsec = tail.time.tv_nsec; 
+            copy_from_log(level, sbuffpos, buf, 
+                          totalsize > max_size ? max_size : totalsize);
+            return totalsize;
+        }
+    }
+    return 0;
+}
+
+#endif
+
+#ifndef TARGET_EXT_SYNC_DISABLE
+
+#define CALIBRATED -2
+#define NOT_CALIBRATED -1
+static int calibration_count = NOT_CALIBRATED;
+static IEC_TIME cal_begin;
+static long long Tsync = 0;
+static long long FreqCorr = 0;
+static int Nticks = 0;
+static unsigned long last_tick = 0;
+
+/*
+ * Called on each external periodic sync event
+ * make PLC tick synchronous with external sync
+ * ratio defines when PLC tick occurs between two external sync
+ * @param sync_align_ratio 
+ *          0->100 : align ratio
+ *          < 0 : no align, calibrate period
+ **/
+void align_tick(int sync_align_ratio)
+{
+	/*
+	printf("align_tick(%d)\n", calibrate);
+	*/
+	if(sync_align_ratio < 0){ /* Calibration */
+		if(calibration_count == CALIBRATED)
+			/* Re-calibration*/
+			calibration_count = NOT_CALIBRATED;
+		if(calibration_count == NOT_CALIBRATED)
+			/* Calibration start, get time*/
+			PLC_GetTime(&cal_begin);
+		calibration_count++;
+	}else{ /* do alignment (if possible) */
+		if(calibration_count >= 0){
+			/* End of calibration */
+			/* Get final time */
+			IEC_TIME cal_end;
+			PLC_GetTime(&cal_end);
+			/*adjust calibration_count*/
+			calibration_count++;
+			/* compute mean of Tsync, over calibration period */
+			Tsync = ((long long)(cal_end.tv_sec - cal_begin.tv_sec) * (long long)1000000000 +
+					(cal_end.tv_nsec - cal_begin.tv_nsec)) / calibration_count;
+			if( (Nticks = (Tsync / common_ticktime__)) > 0){
+				FreqCorr = (Tsync % common_ticktime__); /* to be divided by Nticks */
+			}else{
+				FreqCorr = Tsync - (common_ticktime__ % Tsync);
+			}
+			/*
+			printf("Tsync = %ld\n", Tsync);
+			printf("calibration_count = %d\n", calibration_count);
+			printf("Nticks = %d\n", Nticks);
+			*/
+			calibration_count = CALIBRATED;
+		}
+		if(calibration_count == CALIBRATED){
+			/* Get Elapsed time since last PLC tick (__CURRENT_TIME) */
+			IEC_TIME now;
+			long long elapsed;
+			long long Tcorr;
+			long long PhaseCorr;
+			long long PeriodicTcorr;
+			PLC_GetTime(&now);
+			elapsed = (now.tv_sec - __CURRENT_TIME.tv_sec) * 1000000000 + now.tv_nsec - __CURRENT_TIME.tv_nsec;
+			if(Nticks > 0){
+				PhaseCorr = elapsed - (common_ticktime__ + FreqCorr/Nticks)*sync_align_ratio/100; /* to be divided by Nticks */
+				Tcorr = common_ticktime__ + (PhaseCorr + FreqCorr) / Nticks;
+				if(Nticks < 2){
+					/* When Sync source period is near Tick time */
+					/* PhaseCorr may not be applied to Periodic time given to timer */
+					PeriodicTcorr = common_ticktime__ + FreqCorr / Nticks;
+				}else{
+					PeriodicTcorr = Tcorr;
+				}
+			}else if(__tick > last_tick){
+				last_tick = __tick;
+				PhaseCorr = elapsed - (Tsync*sync_align_ratio/100);
+				PeriodicTcorr = Tcorr = common_ticktime__ + PhaseCorr + FreqCorr;
+			}else{
+				/*PLC did not run meanwhile. Nothing to do*/
+				return;
+			}
+			/* DO ALIGNEMENT */
+			PLC_SetTimer(Tcorr - elapsed, PeriodicTcorr);
+		}
+	}
+}
+
+#endif

Beremiz/beremiz_tutorial_opc_ua/build/py_ext.c

+/*
+ * Python Asynchronous execution code
+ *
+ * PLC put python commands in a fifo, respecting execution order
+ * with the help of C pragmas inserted in python_eval FB code
+ *
+ * Buffer content is read asynchronously, (from non real time part),
+ * commands are executed and result stored for later use by PLC.
+ *
+ * In this implementation, fifo is a list of pointer to python_eval
+ * function blocks structures. Some local variables have been added in
+ * python_eval interface. We use those local variables as buffer and state
+ * flags.
+ *
+ * */
+
+#include "iec_types_all.h"
+#include "POUS.h"
+#include <string.h>
+
+/* The fifo (fixed size, as number of FB is fixed) */
+static PYTHON_EVAL* EvalFBs[1];
+/* Producer and consumer cursors */
+static int Current_PLC_EvalFB;
+static int Current_Python_EvalFB;
+
+/* A global IEC-Python gateway state, for use inside python_eval FBs*/
+static int PythonState;
+#define PYTHON_LOCKED_BY_PYTHON 0
+#define PYTHON_LOCKED_BY_PLC 1
+#define PYTHON_MUSTWAKEUP 2
+#define PYTHON_FINISHED 4
+
+/* Each python_eval FunctionBlock have it own state */
+#define PYTHON_FB_FREE 0
+#define PYTHON_FB_REQUESTED 1
+#define PYTHON_FB_PROCESSING 2
+#define PYTHON_FB_ANSWERED 3
+
+int WaitPythonCommands(void);
+void UnBlockPythonCommands(void);
+int TryLockPython(void);
+void UnLockPython(void);
+void LockPython(void);
+
+int __init_py_ext()
+{
+	int i;
+	/* Initialize cursors */
+	Current_Python_EvalFB = 0;
+	Current_PLC_EvalFB = 0;
+	PythonState = PYTHON_LOCKED_BY_PYTHON;
+	for(i = 0; i < 1; i++)
+		EvalFBs[i] = NULL;
+  return 0;
+}
+
+void __cleanup_py_ext()
+{
+	PythonState = PYTHON_FINISHED;
+	UnBlockPythonCommands();
+}
+
+void __retrieve_py_ext()
+{
+	/* Check Python thread is not being
+	 * modifying internal python_eval data */
+	PythonState = TryLockPython() ?
+	                PYTHON_LOCKED_BY_PLC :
+	                PYTHON_LOCKED_BY_PYTHON;
+	/* If python thread _is_ in, then PythonState remains PYTHON_LOCKED_BY_PYTHON
+	 * and python_eval will no do anything */
+}
+
+void __publish_py_ext()
+{
+	if(PythonState & PYTHON_LOCKED_BY_PLC){
+		/* If runnig PLC did push something in the fifo*/
+		if(PythonState & PYTHON_MUSTWAKEUP){
+			/* WakeUp python thread */
+			UnBlockPythonCommands();
+		}
+		UnLockPython();
+	}
+}
+/**
+ * Called by the PLC, each time a python_eval
+ * FB instance is executed
+ */
+void __PythonEvalFB(int poll, PYTHON_EVAL* data__)
+{
+    if(!__GET_VAR(data__->TRIG)){
+        /* ACK is False when TRIG is false, except a pulse when receiving result */
+        __SET_VAR(data__->, ACK,, 0);
+    }
+	/* detect rising edge on TRIG to trigger evaluation */
+	if(((__GET_VAR(data__->TRIG) && !__GET_VAR(data__->TRIGM1)) ||
+	   /* polling is equivalent to trig on value rather than on rising edge*/
+	    (poll && __GET_VAR(data__->TRIG) )) &&
+	    /* trig only if not already trigged */
+	    __GET_VAR(data__->TRIGGED) == 0){
+		/* mark as trigged */
+	    __SET_VAR(data__->, TRIGGED,, 1);
+		/* make a safe copy of the code */
+		__SET_VAR(data__->, PREBUFFER,, __GET_VAR(data__->CODE));
+	}
+	/* retain value for next rising edge detection */
+	__SET_VAR(data__->, TRIGM1,, __GET_VAR(data__->TRIG));
+
+	/* python thread is not in ? */
+	if( PythonState & PYTHON_LOCKED_BY_PLC){
+		/* if some answer are waiting, publish*/
+		if(__GET_VAR(data__->STATE) == PYTHON_FB_ANSWERED){
+			/* Copy buffer content into result*/
+			__SET_VAR(data__->, RESULT,, __GET_VAR(data__->BUFFER));
+			/* signal result presence to PLC*/
+			__SET_VAR(data__->, ACK,, 1);
+			/* Mark as free */
+			__SET_VAR(data__->, STATE,, PYTHON_FB_FREE);
+			/* mark as not trigged */
+			if(!poll)
+			    __SET_VAR(data__->, TRIGGED,, 0);
+			/*printf("__PythonEvalFB pop %d - %*s\n",Current_PLC_EvalFB, data__->BUFFER.len, data__->BUFFER.body);*/
+		}else if(poll){
+			/* when in polling, no answer == ack down */
+		    __SET_VAR(data__->, ACK,, 0);
+		}
+		/* got the order to act ?*/
+		if(__GET_VAR(data__->TRIGGED) == 1 &&
+		   /* and not already being processed */
+		   __GET_VAR(data__->STATE) == PYTHON_FB_FREE)
+		{
+			/* Enter the block in the fifo
+			 * Don't have to check if fifo cell is free
+			 * as fifo size == FB count, and a FB cannot
+			 * be requested twice */
+			EvalFBs[Current_PLC_EvalFB] = data__;
+			/* copy into BUFFER local*/
+			__SET_VAR(data__->, BUFFER,, __GET_VAR(data__->PREBUFFER));
+			/* Set ACK pin to low so that we can set a rising edge on result */
+			if(!poll){
+				/* when not polling, a new answer imply reseting ack*/
+			    __SET_VAR(data__->, ACK,, 0);
+			}else{
+				/* when in polling, acting reset trigger */
+			    __SET_VAR(data__->, TRIGGED,, 0);
+			}
+			/* Mark FB busy */
+			__SET_VAR(data__->, STATE,, PYTHON_FB_REQUESTED);
+			/* Have to wakeup python thread in case he was asleep */
+			PythonState |= PYTHON_MUSTWAKEUP;
+			/*printf("__PythonEvalFB push %d - %*s\n",Current_PLC_EvalFB, data__->BUFFER.len, data__->BUFFER.body);*/
+			/* Get a new line */
+			Current_PLC_EvalFB = (Current_PLC_EvalFB + 1) % 1;
+		}
+	}
+}
+
+char* PythonIterator(char* result, void** id)
+{
+	char* next_command;
+	PYTHON_EVAL* data__;
+	//printf("PythonIterator result %s\n", result);
+    /*emergency exit*/
+    if(PythonState & PYTHON_FINISHED) return NULL;
+	/* take python mutex to prevent changing PLC data while PLC running */
+	LockPython();
+	/* Get current FB */
+	data__ = EvalFBs[Current_Python_EvalFB];
+	if(data__ && /* may be null at first run */
+	    __GET_VAR(data__->STATE) == PYTHON_FB_PROCESSING){ /* some answer awaited*/
+	   	/* If result not None */
+	   	if(result){
+			/* Get results len */
+	   	    __SET_VAR(data__->, BUFFER, .len, strlen(result));
+			/* prevent results overrun */
+			if(__GET_VAR(data__->BUFFER, .len) > STR_MAX_LEN)
+			{
+			    __SET_VAR(data__->, BUFFER, .len, STR_MAX_LEN);
+				/* TODO : signal error */
+			}
+			/* Copy results to buffer */
+			strncpy((char*)__GET_VAR(data__->BUFFER, .body), result, __GET_VAR(data__->BUFFER,.len));
+	   	}else{
+	   	    __SET_VAR(data__->, BUFFER, .len, 0);
+	   	}
+		/* remove block from fifo*/
+		EvalFBs[Current_Python_EvalFB] = NULL;
+		/* Mark block as answered */
+		__SET_VAR(data__->, STATE,, PYTHON_FB_ANSWERED);
+		/* Get a new line */
+		Current_Python_EvalFB = (Current_Python_EvalFB + 1) % 1;
+		//printf("PythonIterator ++ Current_Python_EvalFB %d\n", Current_Python_EvalFB);
+	}
+	/* while next slot is empty */
+	while(((data__ = EvalFBs[Current_Python_EvalFB]) == NULL) ||
+	 	  /* or doesn't contain command */
+	      __GET_VAR(data__->STATE) != PYTHON_FB_REQUESTED)
+	{
+		UnLockPython();
+		/* wait next FB to eval */
+		//printf("PythonIterator wait\n");
+		if(WaitPythonCommands()) return NULL;
+		/*emergency exit*/
+		if(PythonState & PYTHON_FINISHED) return NULL;
+		LockPython();
+	}
+	/* Mark block as processing */
+	__SET_VAR(data__->, STATE,, PYTHON_FB_PROCESSING);
+	//printf("PythonIterator\n");
+	/* make BUFFER a null terminated string */
+	__SET_VAR(data__->, BUFFER, .body[__GET_VAR(data__->BUFFER, .len)], 0);
+	/* next command is BUFFER */
+	next_command = (char*)__GET_VAR(data__->BUFFER, .body);
+	*id=data__;
+	/* free python mutex */
+	UnLockPython();
+	/* return the next command to eval */
+	return next_command;
+}
+

Beremiz/beremiz_tutorial_opc_ua/build/resource1.c

+/*******************************************/
+/*     FILE GENERATED BY iec2c             */
+/* Editing this file is not recommended... */
+/*******************************************/
+
+#include "iec_std_lib.h"
+
+// RESOURCE RESOURCE1
+
+extern unsigned long long common_ticktime__;
+
+#include "accessor.h"
+#include "POUS.h"
+
+#include "config.h"
+
+#include "POUS.c"
+
+BOOL TASK0;
+PLC_PRG RESOURCE1__INSTANCE0;
+#define INSTANCE0 RESOURCE1__INSTANCE0
+
+void RESOURCE1_init__(void) {
+  BOOL retain;
+  retain = 0;
+  
+  TASK0 = __BOOL_LITERAL(FALSE);
+  PLC_PRG_init__(&INSTANCE0,retain);
+}
+
+void RESOURCE1_run__(unsigned long tick) {
+  TASK0 = !(tick % 1);
+  if (TASK0) {
+    PLC_PRG_body__(&INSTANCE0);
+  }
+}
+

Beremiz/beremiz_tutorial_opc_ua/build/runtime_modbus_websettings.py

+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# This file is part of Beremiz runtime.
+#
+# Copyright (C) 2020: Mario de Sousa
+#
+# See COPYING.Runtime file for copyrights details.
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+
+
+
+##############################################################################################
+# This file implements an extension to the web server embedded in the Beremiz_service.py     #
+# runtime manager (webserver is in runtime/NevowServer.py).                                  #
+#                                                                                            #
+# The extension implemented in this file allows for runtime configuration                    #
+# of Modbus plugin parameters                                                                #
+##############################################################################################
+
+
+
+import json
+import os
+import ctypes
+import string
+import hashlib
+
+from formless import annotate, webform
+
+import runtime.NevowServer as NS
+
+# Directory in which to store the persistent configurations
+# Should be a directory that does not get wiped on reboot!
+_ModbusConfFiledir = WorkingDir
+
+# List of all Web Extension Setting nodes we are handling.
+# One WebNode each for:
+#   - Modbus TCP client 
+#   - Modbus TCP server
+#   - Modbus RTU client
+#   - Modbus RTU slave
+# configured in the loaded PLC (i.e. the .so file loaded into memory)
+# Each entry will be a dictionary. See _AddWebNode() for the details
+# of the data structure in each entry.
+_WebNodeList = []
+
+
+
+
+class MB_StrippedString(annotate.String):
+    def __init__(self, *args, **kwargs):
+        annotate.String.__init__(self, strip = True, *args, **kwargs)
+
+
+class MB_StopBits(annotate.Choice):
+    _choices = [0, 1, 2]
+
+    def coerce(self, val, configurable):
+        return int(val)
+    def __init__(self, *args, **kwargs):
+        annotate.Choice.__init__(self, choices = self._choices, *args, **kwargs)
+
+
+class MB_Baud(annotate.Choice):
+    _choices = [110, 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200]
+
+    def coerce(self, val, configurable):
+        return int(val)
+    def __init__(self, *args, **kwargs):
+        annotate.Choice.__init__(self, choices = self._choices, *args, **kwargs)
+
+
+class MB_Parity(annotate.Choice):
+    # For more info on what this class really does, have a look at the code in
+    # file twisted/nevow/annotate.py
+    # grab this code from $git clone https://github.com/twisted/nevow/
+    # 
+    # Warning: do _not_ name this variable choice[] without underscore, as that name is
+    # already used for another similar variable by the underlying class annotate.Choice
+    _choices = [  0,      1,      2  ]
+    _label   = ["none", "odd", "even"]
+    
+    def choice_to_label(self, key):
+        #PLCObject.LogMessage("Modbus web server extension::choice_to_label()  " + str(key))
+        return self._label[key]
+    
+    def coerce(self, val, configurable):
+        """Coerce a value with the help of an object, which is the object
+        we are configuring.
+        """
+        # Basically, make sure the value the user introduced is valid, and transform
+        # into something that is valid if necessary or mark it as an error 
+        # (by raising an exception ??).
+        #
+        # We are simply using this functions to transform the input value (a string)
+        # into an integer. Note that although the available options are all
+        # integers (0, 1 or 2), even though what is shown on the user interface
+        # are actually strings, i.e. the labels), these parameters are for some 
+        # reason being parsed as strings, so we need to map them back to an
+        # integer.
+        #
+        #PLCObject.LogMessage("Modbus web server extension::coerce  " + val )
+        return int(val)
+
+    def __init__(self, *args, **kwargs):
+        annotate.Choice.__init__(self, 
+                                 choices   = self._choices,
+                                 stringify = self.choice_to_label,
+                                 *args, **kwargs)
+
+
+
+# Parameters we will need to get from the C code, but that will not be shown
+# on the web interface. Common to all modbus entry types (client/server, tcp/rtu/ascii)
+#
+# The annotate type entry is basically useless and is completely ignored.
+# We kee that entry so that this list can later be correctly merged with the
+# following lists...
+General_parameters = [
+    #    param. name       label                        ctype type         annotate type
+    # (C code var name)   (used on web interface)      (C data type)       (web data type)
+    #                                                                      (annotate.String,
+    #                                                                       annotate.Integer, ...)
+    ("config_name"      , _("")                      , ctypes.c_char_p,    annotate.String),
+    ("addr_type"        , _("")                      , ctypes.c_char_p,    annotate.String)
+    ]                                                                      
+                                                                           
+# Parameters we will need to get from the C code, and that _will_ be shown
+# on the web interface.
+TCPclient_parameters = [                                                   
+    #    param. name       label                        ctype type         annotate type
+    # (C code var name)   (used on web interface)      (C data type)       (web data type)
+    #                                                                      (annotate.String,
+    #                                                                       annotate.Integer, ...)
+    ("host"             , _("Remote IP Address")     , ctypes.c_char_p,    MB_StrippedString),
+    ("port"             , _("Remote Port Number")    , ctypes.c_char_p,    MB_StrippedString),
+    ("comm_period"      , _("Invocation Rate (ms)")  , ctypes.c_ulonglong, annotate.Integer )
+    ]
+
+RTUclient_parameters = [                                                   
+    #    param. name       label                        ctype type         annotate type
+    # (C code var name)   (used on web interface)      (C data type)       (web data type)
+    #                                                                      (annotate.String,
+    #                                                                       annotate.Integer, ...)
+    ("device"           , _("Serial Port")           , ctypes.c_char_p,    MB_StrippedString),
+    ("baud"             , _("Baud Rate")             , ctypes.c_int,       MB_Baud         ),
+    ("parity"           , _("Parity")                , ctypes.c_int,       MB_Parity       ),
+    ("stop_bits"        , _("Stop Bits")             , ctypes.c_int,       MB_StopBits     ),
+    ("comm_period"      , _("Invocation Rate (ms)")  , ctypes.c_ulonglong, annotate.Integer)
+    ]
+
+TCPserver_parameters = [                                                   
+    #    param. name       label                        ctype type         annotate type
+    # (C code var name)   (used on web interface)      (C data type)       (web data type)
+    #                                                                      (annotate.String,
+    #                                                                       annotate.Integer, ...)
+    ("host"             , _("Local IP Address")      , ctypes.c_char_p,    MB_StrippedString),
+    ("port"             , _("Local Port Number")     , ctypes.c_char_p,    MB_StrippedString),
+    ("slave_id"         , _("Slave ID")              , ctypes.c_ubyte,     annotate.Integer )
+    ]
+
+RTUslave_parameters = [                                                   
+    #    param. name       label                        ctype type         annotate type
+    # (C code var name)   (used on web interface)      (C data type)       (web data type)
+    #                                                                      (annotate.String,
+    #                                                                       annotate.Integer, ...)
+    ("device"           , _("Serial Port")           , ctypes.c_char_p,    MB_StrippedString),
+    ("baud"             , _("Baud Rate")             , ctypes.c_int,       MB_Baud         ),
+    ("parity"           , _("Parity")                , ctypes.c_int,       MB_Parity       ),
+    ("stop_bits"        , _("Stop Bits")             , ctypes.c_int,       MB_StopBits     ),
+    ("slave_id"         , _("Slave ID")              , ctypes.c_ubyte,     annotate.Integer)
+    ]
+
+
+
+
+# Dictionary containing List of Web viewable parameters
+# Note: the dictionary key must be the same as the string returned by the 
+# __modbus_get_ClientNode_addr_type()
+# __modbus_get_ServerNode_addr_type()
+# functions implemented in C (see modbus/mb_runtime.c)
+_client_WebParamListDict = {}
+_client_WebParamListDict["tcp"  ] = TCPclient_parameters
+_client_WebParamListDict["rtu"  ] = RTUclient_parameters
+_client_WebParamListDict["ascii"] = []  # (Note: ascii not yet implemented in Beremiz modbus plugin)
+
+_server_WebParamListDict = {}
+_server_WebParamListDict["tcp"  ] = TCPserver_parameters
+_server_WebParamListDict["rtu"  ] = RTUslave_parameters
+_server_WebParamListDict["ascii"] = []  # (Note: ascii not yet implemented in Beremiz modbus plugin)
+
+WebParamListDictDict = {}
+WebParamListDictDict['client'] = _client_WebParamListDict
+WebParamListDictDict['server'] = _server_WebParamListDict
+
+
+
+
+
+
+def _SetModbusSavedConfiguration(WebNode_id, newConfig):
+    """ Stores a dictionary in a persistant file containing the Modbus parameter configuration """
+    WebNode_entry = _WebNodeList[WebNode_id]
+
+    if WebNode_entry["DefaultConfiguration"] == newConfig:
+
+        _DelModbusSavedConfiguration(WebNode_id)
+        WebNode_entry["ModbusSavedConfiguration"] = None
+
+    else:
+
+        # Add the addr_type and node_type to the data that will be saved to file
+        # This allows us to confirm the saved data contains the correct addr_type
+        # when loading from file
+        save_info = {}
+        save_info["addr_type"] = WebNode_entry["addr_type"]
+        save_info["node_type"] = WebNode_entry["node_type"]
+        save_info["config"   ] = newConfig
+        
+        filename = WebNode_entry["filename"]
+
+        with open(os.path.realpath(filename), 'w') as f:
+            json.dump(save_info, f, sort_keys=True, indent=4)
+            
+        WebNode_entry["ModbusSavedConfiguration"] = newConfig
+
+
+
+
+def _DelModbusSavedConfiguration(WebNode_id):
+    """ Deletes the file cotaining the persistent Modbus configuration """
+    filename = _WebNodeList[WebNode_id]["filename"]
+    
+    if os.path.exists(filename):
+        os.remove(filename)
+
+
+
+
+def _GetModbusSavedConfiguration(WebNode_id):
+    """
+    Returns a dictionary containing the Modbus parameter configuration
+    that was last saved to file. If no file exists, or file contains 
+    wrong addr_type (i.e. 'tcp', 'rtu' or 'ascii' -> does not match the
+    addr_type of the WebNode_id), then return None
+    """
+    filename = _WebNodeList[WebNode_id]["filename"]
+    try:
+        #if os.path.isfile(filename):
+        save_info = json.load(open(os.path.realpath(filename)))
+    except Exception:    
+        return None
+
+    if save_info["addr_type"] != _WebNodeList[WebNode_id]["addr_type"]:
+        return None
+    if save_info["node_type"] != _WebNodeList[WebNode_id]["node_type"]:
+        return None
+    if "config" not in save_info:
+        return None
+    
+    saved_config = save_info["config"]
+    
+    #if _CheckConfiguration(saved_config):
+    #    return saved_config
+    #else:
+    #    return None
+
+    return saved_config
+
+
+
+def _GetModbusPLCConfiguration(WebNode_id):
+    """
+    Returns a dictionary containing the current Modbus parameter configuration
+    stored in the C variables in the loaded PLC (.so file)
+    """
+    current_config = {}
+    C_node_id      = _WebNodeList[WebNode_id]["C_node_id"]
+    WebParamList   = _WebNodeList[WebNode_id]["WebParamList"]
+    GetParamFuncs  = _WebNodeList[WebNode_id]["GetParamFuncs"]
+
+    for par_name, x1, x2, x3 in WebParamList:
+        value = GetParamFuncs[par_name](C_node_id)
+        if value is not None:
+            current_config[par_name] = value
+    
+    return current_config
+
+
+
+def _SetModbusPLCConfiguration(WebNode_id, newconfig):
+    """
+    Stores the Modbus parameter configuration into the
+    the C variables in the loaded PLC (.so file)
+    """
+    C_node_id      = _WebNodeList[WebNode_id]["C_node_id"]
+    SetParamFuncs  = _WebNodeList[WebNode_id]["SetParamFuncs"]
+
+    for par_name in newconfig:
+        value = newconfig[par_name]
+        if value is not None:
+            SetParamFuncs[par_name](C_node_id, value)
+            
+
+
+
+def _GetModbusWebviewConfigurationValue(ctx, WebNode_id, argument):
+    """
+    Callback function, called by the web interface (NevowServer.py)
+    to fill in the default value of each parameter of the web form
+    
+    Note that the real callback function is a dynamically created function that
+    will simply call this function to do the work. It will also pass the WebNode_id 
+    as a parameter.
+    """    
+    try:
+        return _WebNodeList[WebNode_id]["WebviewConfiguration"][argument.name]
+    except Exception:
+        return ""
+
+
+
+def OnModbusButtonSave(**kwargs):
+    """
+    Function called when user clicks 'Save' button in web interface
+    The function will configure the Modbus plugin in the PLC with the values
+    specified in the web interface. However, values must be validated first!
+    
+    Note that this function does not get called directly. The real callback
+    function is the dynamic __OnButtonSave() function, which will add the 
+    "WebNode_id" argument, and call this function to do the work.
+    """
+
+    #PLCObject.LogMessage("Modbus web server extension::OnModbusButtonSave()  Called")
+    
+    newConfig    = {}
+    WebNode_id   =  kwargs.get("WebNode_id", None)
+    WebParamList = _WebNodeList[WebNode_id]["WebParamList"]
+    
+    for par_name, x1, x2, x3 in WebParamList:
+        value = kwargs.get(par_name, None)
+        if value is not None:
+            newConfig[par_name] = value
+
+    # First check if configuration is OK.
+    # Note that this is not currently required, as we use drop down choice menus
+    # for baud, parity and sop bits, so the values should always be correct!
+    #if not _CheckWebConfiguration(newConfig):
+    #    return
+    
+    # store to file the new configuration so that 
+    # we can recoup the configuration the next time the PLC
+    # has a cold start (i.e. when Beremiz_service.py is retarted)
+    _SetModbusSavedConfiguration(WebNode_id, newConfig)
+
+    # Configure PLC with the current Modbus parameters
+    _SetModbusPLCConfiguration(WebNode_id, newConfig)
+
+    # Update the viewable configuration
+    # The PLC may have coerced the values on calling _SetModbusPLCConfiguration()
+    # so we do not set it directly to newConfig
+    _WebNodeList[WebNode_id]["WebviewConfiguration"] = _GetModbusPLCConfiguration(WebNode_id)
+
+
+
+def OnModbusButtonReset(**kwargs):
+    """
+    Function called when user clicks 'Delete' button in web interface
+    The function will delete the file containing the persistent
+    Modbus configution
+    """
+
+    WebNode_id = kwargs.get("WebNode_id", None)
+    
+    # Delete the file
+    _DelModbusSavedConfiguration(WebNode_id)
+
+    # Set the current configuration to the default (hardcoded in C)
+    new_config = _WebNodeList[WebNode_id]["DefaultConfiguration"]
+    _SetModbusPLCConfiguration(WebNode_id, new_config)
+    
+    #Update the webviewconfiguration
+    _WebNodeList[WebNode_id]["WebviewConfiguration"] = new_config
+    
+    # Reset ModbusSavedConfiguration
+    _WebNodeList[WebNode_id]["ModbusSavedConfiguration"] = None
+    
+
+
+
+
+def _AddWebNode(C_node_id, node_type, GetParamFuncs, SetParamFuncs):
+    """
+    Load from the compiled code (.so file, aloready loaded into memmory)
+    the configuration parameters of a specific Modbus plugin node.
+    This function works with both client and server nodes, depending on the
+    Get/SetParamFunc dictionaries passed to it (either the client or the server
+    node versions of the Get/Set functions)
+    """
+    WebNode_entry = {}
+
+    # Get the config_name from the C code...
+    config_name = GetParamFuncs["config_name"](C_node_id)
+    # Get the addr_type from the C code...
+    # addr_type will be one of "tcp", "rtu" or "ascii"
+    addr_type   = GetParamFuncs["addr_type"  ](C_node_id)   
+    # For some operations we cannot use the config name (e.g. filename to store config)
+    # because the user may be using characters that are invalid for that purpose ('/' for
+    # example), so we create a hash of the config_name, and use that instead.
+    config_hash = hashlib.md5(config_name).hexdigest()
+    
+    #PLCObject.LogMessage("Modbus web server extension::_AddWebNode("+str(C_node_id)+") config_name="+config_name)
+
+    # Add the new entry to the global list
+    # Note: it is OK, and actually necessary, to do this _before_ seting all the parameters in WebNode_entry
+    #       WebNode_entry will be stored as a reference, so we can later insert parameters at will.
+    global _WebNodeList
+    _WebNodeList.append(WebNode_entry)
+    WebNode_id = len(_WebNodeList) - 1
+
+    # store all WebNode relevant data for future reference
+    #
+    # Note that "WebParamList" will reference one of:
+    #  - TCPclient_parameters, TCPserver_parameters, RTUclient_parameters, RTUslave_parameters
+    WebNode_entry["C_node_id"    ] = C_node_id
+    WebNode_entry["config_name"  ] = config_name 
+    WebNode_entry["config_hash"  ] = config_hash
+    WebNode_entry["filename"     ] = os.path.join(_ModbusConfFiledir, "Modbus_config_" + config_hash + ".json")
+    WebNode_entry["GetParamFuncs"] = GetParamFuncs
+    WebNode_entry["SetParamFuncs"] = SetParamFuncs
+    WebNode_entry["WebParamList" ] = WebParamListDictDict[node_type][addr_type] 
+    WebNode_entry["addr_type"    ] = addr_type  # 'tcp', 'rtu', or 'ascii' (as returned by C function)
+    WebNode_entry["node_type"    ] = node_type  # 'client', 'server'
+        
+    
+    # Dictionary that contains the Modbus configuration currently being shown
+    # on the web interface
+    # This configuration will almost always be identical to the current
+    # configuration in the PLC (i.e., the current state stored in the 
+    # C variables in the .so file).
+    # The configuration viewed on the web will only be different to the current 
+    # configuration when the user edits the configuration, and when
+    # the user asks to save an edited configuration that contains an error.
+    WebNode_entry["WebviewConfiguration"] = None
+
+    # Upon PLC load, this Dictionary is initialised with the Modbus configuration
+    # hardcoded in the C file
+    # (i.e. the configuration inserted in Beremiz IDE when project was compiled)
+    WebNode_entry["DefaultConfiguration"] = _GetModbusPLCConfiguration(WebNode_id)
+    WebNode_entry["WebviewConfiguration"] = WebNode_entry["DefaultConfiguration"]
+    
+    # Dictionary that stores the Modbus configuration currently stored in a file
+    # Currently only used to decide whether or not to show the "Delete" button on the
+    # web interface (only shown if "ModbusSavedConfiguration" is not None)
+    SavedConfig = _GetModbusSavedConfiguration(WebNode_id)
+    WebNode_entry["ModbusSavedConfiguration"] = SavedConfig
+    
+    if SavedConfig is not None:
+        _SetModbusPLCConfiguration(WebNode_id, SavedConfig)
+        WebNode_entry["WebviewConfiguration"] = SavedConfig
+        
+    # Define the format for the web form used to show/change the current parameters
+    # We first declare a dynamic function to work as callback to obtain the default values for each parameter
+    # Note: We transform every parameter into a string
+    #       This is not strictly required for parameters of type annotate.Integer that will correctly
+    #           accept the default value as an Integer python object
+    #       This is obviously also not required for parameters of type annotate.String, that are
+    #           always handled as strings.
+    #       However, the annotate.Choice parameters (and all parameters that derive from it,
+    #           sucn as Parity, Baud, etc.) require the default value as a string
+    #           even though we store it as an integer, which is the data type expected
+    #           by the set_***() C functions in mb_runtime.c
+    def __GetWebviewConfigurationValue(ctx, argument):
+        return str(_GetModbusWebviewConfigurationValue(ctx, WebNode_id, argument))
+    
+    webFormInterface = [(name, web_dtype (label=web_label, default=__GetWebviewConfigurationValue)) 
+                    for name, web_label, c_dtype, web_dtype in WebNode_entry["WebParamList"]]
+
+    # Configure the web interface to include the Modbus config parameters
+    def __OnButtonSave(**kwargs):
+        OnModbusButtonSave(WebNode_id=WebNode_id, **kwargs)
+
+    WebSettings = NS.newExtensionSetting("Modbus #"+ str(WebNode_id), config_hash)
+
+    WebSettings.addSettings(
+        "ModbusConfigParm"          + config_hash,     # name (internal, may not contain spaces, ...)
+        _("Modbus Configuration: ") + config_name,     # description (user visible label)
+        webFormInterface,                              # fields
+        _("Apply"), # button label
+        __OnButtonSave)                                # callback   
+    
+    def __OnButtonReset(**kwargs):
+        return OnModbusButtonReset(WebNode_id = WebNode_id, **kwargs)
+            
+    def getModbusConfigStatus():
+        if WebNode_entry["WebviewConfiguration"] == WebNode_entry["DefaultConfiguration"]:
+            return "Unchanged"
+        return "Modified"
+
+    WebSettings.addSettings(
+        "ModbusConfigDelSaved"      + config_hash,  # name (internal, may not contain spaces, ...)
+        _("Modbus Configuration: ") + config_name,  # description (user visible label)
+        [ ("status",
+           annotate.String(label=_("Current state"),
+                           immutable=True,
+                           default=lambda *k:getModbusConfigStatus())),
+        ],                                       # fields  (empty, no parameters required!)
+        _("Reset"), # button label
+        __OnButtonReset)
+
+
+
+
+def _runtime_0_modbus_websettings_init():
+    """
+    Callback function, called (by PLCObject.py) when a new PLC program
+    (i.e. XXX.so file) is transfered to the PLC runtime
+    and loaded into memory
+    """
+
+    #PLCObject.LogMessage("Modbus web server extension::OnLoadPLC() Called...")
+
+    if PLCObject.PLClibraryHandle is None:
+        # PLC was loaded but we don't have access to the library of compiled code (.so lib)?
+        # Hmm... This shold never occur!! 
+        return  
+    
+    # Get the number of Modbus Client and Servers (Modbus plugin)
+    # configured in the currently loaded PLC project (i.e., the .so file)
+    # If the "__modbus_plugin_client_node_count" 
+    # or the "__modbus_plugin_server_node_count" C variables 
+    # are not present in the .so file we conclude that the currently loaded 
+    # PLC does not have the Modbus plugin included (situation (2b) described above init())
+    try:
+        # XXX TODO : stop reading from PLC .so file. This code is template code
+        #            that can use modbus extension build data, such as client node count.
+        client_count = ctypes.c_int.in_dll(PLCObject.PLClibraryHandle, "__modbus_plugin_client_node_count").value
+        server_count = ctypes.c_int.in_dll(PLCObject.PLClibraryHandle, "__modbus_plugin_server_node_count").value
+    except Exception:
+        # Loaded PLC does not have the Modbus plugin => nothing to do
+        #   (i.e. do _not_ configure and make available the Modbus web interface)
+        return
+
+    if client_count < 0: client_count = 0
+    if server_count < 0: server_count = 0
+    
+    if (client_count == 0) and (server_count == 0):
+        # The Modbus plugin in the loaded PLC does not have any client and servers configured
+        #  => nothing to do (i.e. do _not_ configure and make available the Modbus web interface)
+        return
+    
+    # Map the get/set functions (written in C code) we will be using to get/set the configuration parameters
+    # Will contain references to the C functions (implemented in beremiz/modbus/mb_runtime.c)
+    GetClientParamFuncs = {}
+    SetClientParamFuncs = {}
+    GetServerParamFuncs = {}
+    SetServerParamFuncs = {}
+
+    # XXX TODO : stop reading from PLC .so file. This code is template code
+    #            that can use modbus extension build data
+    for name, web_label, c_dtype, web_dtype in TCPclient_parameters + RTUclient_parameters + General_parameters:
+        ParamFuncName                      = "__modbus_get_ClientNode_" + name        
+        GetClientParamFuncs[name]          = getattr(PLCObject.PLClibraryHandle, ParamFuncName)
+        GetClientParamFuncs[name].restype  = c_dtype
+        GetClientParamFuncs[name].argtypes = [ctypes.c_int]
+        
+    for name, web_label, c_dtype, web_dtype in TCPclient_parameters + RTUclient_parameters:
+        ParamFuncName                      = "__modbus_set_ClientNode_" + name
+        SetClientParamFuncs[name]          = getattr(PLCObject.PLClibraryHandle, ParamFuncName)
+        SetClientParamFuncs[name].restype  = None
+        SetClientParamFuncs[name].argtypes = [ctypes.c_int, c_dtype]
+
+    # XXX TODO : stop reading from PLC .so file. This code is template code
+    #            that can use modbus extension build data
+    for name, web_label, c_dtype, web_dtype in TCPserver_parameters + RTUslave_parameters + General_parameters:
+        ParamFuncName                      = "__modbus_get_ServerNode_" + name        
+        GetServerParamFuncs[name]          = getattr(PLCObject.PLClibraryHandle, ParamFuncName)
+        GetServerParamFuncs[name].restype  = c_dtype
+        GetServerParamFuncs[name].argtypes = [ctypes.c_int]
+        
+    for name, web_label, c_dtype, web_dtype in TCPserver_parameters + RTUslave_parameters:
+        ParamFuncName                      = "__modbus_set_ServerNode_" + name
+        SetServerParamFuncs[name]          = getattr(PLCObject.PLClibraryHandle, ParamFuncName)
+        SetServerParamFuncs[name].restype  = None
+        SetServerParamFuncs[name].argtypes = [ctypes.c_int, c_dtype]
+
+    for node_id in range(client_count):
+        _AddWebNode(node_id, "client" ,GetClientParamFuncs, SetClientParamFuncs)
+
+    for node_id in range(server_count):
+        _AddWebNode(node_id, "server", GetServerParamFuncs, SetServerParamFuncs)
+
+
+
+
+
+def _runtime_0_modbus_websettings_cleanup():
+    """
+    Callback function, called (by PLCObject.py) when a PLC program is unloaded from memory
+    """
+
+    #PLCObject.LogMessage("Modbus web server extension::OnUnLoadPLC() Called...")
+    
+    # Delete the Modbus specific web interface extensions
+    # (Safe to ask to delete, even if it has not been added!)
+    global _WebNodeList
+    for index, WebNode_entry in enumerate(_WebNodeList):
+        config_hash = WebNode_entry["config_hash"]
+        NS.removeExtensionSetting(config_hash)
+        
+    # Dele all entries...
+    _WebNodeList = []
+

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/ModbusTCPclient_0@ModbusTCPclient/ModbusRequest_0@ModbusRequest/baseconfnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<BaseParams xmlns:xsd="http://www.w3.org/2001/XMLSchema" IEC_Channel="0" Name="ModbusRequest_0"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/ModbusTCPclient_0@ModbusTCPclient/ModbusRequest_0@ModbusRequest/confnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<ModbusRequest xmlns:xsd="http://www.w3.org/2001/XMLSchema" Write_on_change="false" SlaveID="0" Function="05 - Write Single coil" Timeout_in_ms="30"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/ModbusTCPclient_0@ModbusTCPclient/ModbusRequest_1@ModbusRequest/baseconfnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<BaseParams xmlns:xsd="http://www.w3.org/2001/XMLSchema" IEC_Channel="1" Name="ModbusRequest_1"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/ModbusTCPclient_0@ModbusTCPclient/ModbusRequest_1@ModbusRequest/confnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<ModbusRequest xmlns:xsd="http://www.w3.org/2001/XMLSchema" Function="05 - Write Single coil" Write_on_change="false" Start_Address="1" SlaveID="0" Timeout_in_ms="30"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/ModbusTCPclient_0@ModbusTCPclient/ModbusRequest_2@ModbusRequest/baseconfnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<BaseParams xmlns:xsd="http://www.w3.org/2001/XMLSchema" IEC_Channel="2" Name="ModbusRequest_2"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/ModbusTCPclient_0@ModbusTCPclient/ModbusRequest_2@ModbusRequest/confnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<ModbusRequest xmlns:xsd="http://www.w3.org/2001/XMLSchema" Function="05 - Write Single coil" Start_Address="2" SlaveID="0" Timeout_in_ms="30"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/ModbusTCPclient_0@ModbusTCPclient/ModbusRequest_3@ModbusRequest/baseconfnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<BaseParams xmlns:xsd="http://www.w3.org/2001/XMLSchema" IEC_Channel="3" Name="ModbusRequest_3"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/ModbusTCPclient_0@ModbusTCPclient/ModbusRequest_3@ModbusRequest/confnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<ModbusRequest xmlns:xsd="http://www.w3.org/2001/XMLSchema" Function="05 - Write Single coil" SlaveID="0" Start_Address="3" Timeout_in_ms="30"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/ModbusTCPclient_0@ModbusTCPclient/baseconfnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<BaseParams xmlns:xsd="http://www.w3.org/2001/XMLSchema" IEC_Channel="0" Name="ModbusTCPclient_0"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/ModbusTCPclient_0@ModbusTCPclient/confnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<ModbusTCPclient xmlns:xsd="http://www.w3.org/2001/XMLSchema" Configuration_Name="Modbus TCP Client 0.0" Remote_IP_Address="192.168.0.78" Invocation_Rate_in_ms="1000" Remote_Port_Number="1502"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/baseconfnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<BaseParams xmlns:xsd="http://www.w3.org/2001/XMLSchema" IEC_Channel="0" Name="modbus_0"/>

Beremiz/beremiz_tutorial_opc_ua/modbus_0@modbus/confnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<ModbusRoot xmlns:xsd="http://www.w3.org/2001/XMLSchema"/>

Beremiz/beremiz_tutorial_opc_ua/opcua_0@opcua/baseconfnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<BaseParams xmlns:xsd="http://www.w3.org/2001/XMLSchema" IEC_Channel="1" Name="opcua_0"/>

Beremiz/beremiz_tutorial_opc_ua/opcua_0@opcua/confnode.xml

+<?xml version='1.0' encoding='utf-8'?>
+<OPCUAClient xmlns:xsd="http://www.w3.org/2001/XMLSchema" Server_URI="opc.tcp://192.168.0.78:4840"/>

Beremiz/beremiz_tutorial_opc_ua/opcua_0@opcua/selected.csv

+input,"LocalizedText(Encoding:3, Locale:en-US, Text:Relay 0)",1,str,relay0,Int32,0
+input,"LocalizedText(Encoding:3, Locale:en-US, Text:Relay 1)",1,str,relay1,Int32,1
+input,"LocalizedText(Encoding:3, Locale:en-US, Text:Relay 2)",1,str,relay2,Int32,2
+input,"LocalizedText(Encoding:3, Locale:en-US, Text:Relay 3)",1,str,relay3,Int32,3
+output,"LocalizedText(Encoding:3, Locale:en-US, Text:Relay 0)",1,str,relay0,Int32,0
+output,"LocalizedText(Encoding:3, Locale:en-US, Text:Relay 1)",1,str,relay1,Int32,1
+output,"LocalizedText(Encoding:3, Locale:en-US, Text:Relay 2)",1,str,relay2,Int32,2
+output,"LocalizedText(Encoding:3, Locale:en-US, Text:Relay 3)",1,str,relay3,Int32,3

Beremiz/beremiz_tutorial_opc_ua/plc.xml

+<?xml version='1.0' encoding='utf-8'?>
+<project xmlns:ns1="http://www.plcopen.org/xml/tc6_0201" xmlns:xhtml="http://www.w3.org/1999/xhtml" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.plcopen.org/xml/tc6_0201">
+  <fileHeader companyName="Unknown" productName="Unnamed" productVersion="1" creationDateTime="2021-05-14T14:33:11"/>
+  <contentHeader name="Counter (OSIE)" modificationDateTime="2021-10-20T13:35:20">
+    <coordinateInfo>
+      <fbd>
+        <scaling x="0" y="0"/>
+      </fbd>
+      <ld>
+        <scaling x="0" y="0"/>
+      </ld>
+      <sfc>
+        <scaling x="0" y="0"/>
+      </sfc>
+    </coordinateInfo>
+  </contentHeader>
+  <types>
+    <dataTypes/>
+    <pous>
+      <pou name="plc_prg" pouType="program">
+        <interface>
+          <inputVars>
+            <variable name="Reset">
+              <type>
+                <BOOL/>
+              </type>
+            </variable>
+          </inputVars>
+          <outputVars>
+            <variable name="Cnt0">
+              <type>
+                <INT/>
+              </type>
+            </variable>
+            <variable name="Cnt1">
+              <type>
+                <INT/>
+              </type>
+            </variable>
+          </outputVars>
+          <localVars>
+            <variable name="CounterST0">
+              <type>
+                <derived name="CounterST"/>
+              </type>
+            </variable>
+          </localVars>
+        </interface>
+        <body>
+          <FBD>
+            <comment localId="1" height="143" width="201">
+              <position x="566" y="75"/>
+              <content>
+                <xhtml:p><![CDATA[Test Ivan: this PLC will switch ON / OFF attached over modbus relays {0..3} of a Lime2 coupler.]]></xhtml:p>
+              </content>
+            </comment>
+            <block localId="2" typeName="CounterST" instanceName="CounterST0" executionOrderId="0" height="109" width="99">
+              <position x="288" y="192"/>
+              <inputVariables>
+                <variable formalParameter="Reset">
+                  <connectionPointIn>
+                    <relPosition x="0" y="42"/>
+                    <connection refLocalId="3">
+                      <position x="288" y="234"/>
+                      <position x="258" y="234"/>
+                      <position x="258" y="218"/>
+                      <position x="231" y="218"/>
+                    </connection>
+                  </connectionPointIn>
+                </variable>
+              </inputVariables>
+              <inOutVariables/>
+              <outputVariables>
+                <variable formalParameter="Out1">
+                  <connectionPointOut>
+                    <relPosition x="99" y="42"/>
+                  </connectionPointOut>
+                </variable>
+                <variable formalParameter="Out0">
+                  <connectionPointOut>
+                    <relPosition x="99" y="86"/>
+                  </connectionPointOut>
+                </variable>
+              </outputVariables>
+            </block>
+            <inVariable localId="3" executionOrderId="0" height="24" width="50" negated="false">
+              <position x="181" y="206"/>
+              <connectionPointOut>
+                <relPosition x="50" y="12"/>
+              </connectionPointOut>
+              <expression>Reset</expression>
+            </inVariable>
+            <outVariable localId="4" executionOrderId="0" height="24" width="42" negated="false">
+              <position x="433" y="266"/>
+              <connectionPointIn>
+                <relPosition x="0" y="12"/>
+                <connection refLocalId="2" formalParameter="Out0">
+                  <position x="433" y="278"/>
+                  <position x="387" y="278"/>
+                </connection>
+              </connectionPointIn>
+              <expression>Cnt0</expression>
+            </outVariable>
+            <outVariable localId="6" executionOrderId="0" height="24" width="42" negated="false">
+              <position x="435" y="222"/>
+              <connectionPointIn>
+                <relPosition x="0" y="12"/>
+                <connection refLocalId="2" formalParameter="Out1">
+                  <position x="435" y="234"/>
+                  <position x="387" y="234"/>
+                </connection>
+              </connectionPointIn>
+              <expression>Cnt1</expression>
+            </outVariable>
+          </FBD>
+        </body>
+      </pou>
+      <pou name="CounterST" pouType="functionBlock">
+        <interface>
+          <inputVars>
+            <variable name="Reset">
+              <type>
+                <BOOL/>
+              </type>
+            </variable>
+          </inputVars>
+          <outputVars>
+            <variable name="Out1">
+              <type>
+                <INT/>
+              </type>
+            </variable>
+            <variable name="Out0">
+              <type>
+                <INT/>
+              </type>
+            </variable>
+          </outputVars>
+          <localVars>
+            <variable name="Cnt1">
+              <type>
+                <INT/>
+              </type>
+            </variable>
+            <variable name="Cnt0">
+              <type>
+                <INT/>
+              </type>
+            </variable>
+          </localVars>
+          <externalVars>
+            <variable name="ResetCounterValue">
+              <type>
+                <INT/>
+              </type>
+            </variable>
+            <variable name="Relay0Value">
+              <type>
+                <BOOL/>
+              </type>
+            </variable>
+            <variable name="Relay1Value">
+              <type>
+                <BOOL/>
+              </type>
+            </variable>
+            <variable name="Relay2Value">
+              <type>
+                <BOOL/>
+              </type>
+            </variable>
+            <variable name="Relay3Value">
+              <type>
+                <BOOL/>
+              </type>
+            </variable>
+            <variable name="Relay3Value0">
+              <type>
+                <DINT/>
+              </type>
+            </variable>
+          </externalVars>
+        </interface>
+        <body>
+          <ST>
+            <xhtml:p><![CDATA[IF Reset THEN
+  Cnt0 := ResetCounterValue;
+  Cnt1 := ResetCounterValue;
+  Reset := False;
+ELSE
+  Cnt0 := Cnt0 + 1;
+  Cnt1 := Cnt1 + 1;
+  IF Cnt1 = 100 THEN
+    Relay3Value0 := 1;
+  END_IF;
+  
+  IF Cnt1 = 500 THEN
+    Relay3Value0 := 0;
+  END_IF;
+  
+END_IF;
+
+Out1 := Cnt1;
+Out0 := Cnt0;]]></xhtml:p>
+          </ST>
+        </body>
+      </pou>
+    </pous>
+  </types>
+  <instances>
+    <configurations>
+      <configuration name="config">
+        <resource name="resource1">
+          <task name="task0" priority="0" interval="T#20ms">
+            <pouInstance name="instance0" typeName="plc_prg"/>
+          </task>
+        </resource>
+        <globalVars>
+          <variable name="ResetCounterValue">
+            <type>
+              <INT/>
+            </type>
+            <initialValue>
+              <simpleValue value="0"/>
+            </initialValue>
+          </variable>
+          <variable name="Relay0Value" address="%QX0.0.0.0">
+            <type>
+              <BOOL/>
+            </type>
+            <initialValue>
+              <simpleValue value="0"/>
+            </initialValue>
+            <documentation>
+              <xhtml:p><![CDATA[The status of the Lime's relay0 (read over modbus)]]></xhtml:p>
+            </documentation>
+          </variable>
+          <variable name="Relay1Value" address="%QX0.0.1.1">
+            <type>
+              <BOOL/>
+            </type>
+            <initialValue>
+              <simpleValue value="0"/>
+            </initialValue>
+            <documentation>
+              <xhtml:p><![CDATA[The status of the Lime's relay1 (read over modbus)]]></xhtml:p>
+            </documentation>
+          </variable>
+          <variable name="Relay2Value" address="%QX0.0.2.2">
+            <type>
+              <BOOL/>
+            </type>
+            <initialValue>
+              <simpleValue value="0"/>
+            </initialValue>
+            <documentation>
+              <xhtml:p><![CDATA[The status of the Lime's relay2 (read over modbus)]]></xhtml:p>
+            </documentation>
+          </variable>
+          <variable name="Relay3Value" address="%QX0.0.3.3">
+            <type>
+              <BOOL/>
+            </type>
+            <initialValue>
+              <simpleValue value="0"/>
+            </initialValue>
+            <documentation>
+              <xhtml:p><![CDATA[The status of the Lime's relay3 (read over modbus)]]></xhtml:p>
+            </documentation>
+          </variable>
+          <variable name="Relay3Value0" address="%QD1.0">
+            <type>
+              <DINT/>
+            </type>
+            <initialValue>
+              <simpleValue value="0"/>
+            </initialValue>
+            <documentation>
+              <xhtml:p><![CDATA[OPC-UA relay valu]]></xhtml:p>
+            </documentation>
+          </variable>
+        </globalVars>
+      </configuration>
+    </configurations>
+  </instances>
+</project>