Expose variables over OPC-UA.

coupler/opc-ua-server/ic2_set_relays_example.c

-/*
-  Example controling MOD-IO's relays' state 
-  Based on https://www.kernel.org/doc/Documentation/i2c/dev-interface
-  
-  To compile:
-    root@olimex-rt:~/osie/coupler/opc-ua-server# gcc ic2_set_relays_example.c -o ic2_set_relays_example
-    root@olimex-rt:~/osie/coupler/opc-ua-server# ./ic2_set_relays_example
-*/
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <stdint.h>
-#include <linux/i2c-dev.h>
-#include <fcntl.h>
-#include <sys/ioctl.h>
-#include <unistd.h>
-
-int main()
-{
-   int file;
-   int adapter_nr = 1; /* probably dynamically determined */
-   int addr = 0x58; /* The I2C slave's address */
-   char filename[20];
-
-   // step 1: open device
-   snprintf(filename, 19, "/dev/i2c-%d", adapter_nr);
-   file = open(filename, O_RDWR);
-   if (file < 0) {
-     /* ERROR HANDLING; you can check errno to see what went wrong */
-     printf("Error openind i2c device.");
-     exit(1);
-   }
-  
-   // step 2: address the slave by its address 
-   if (ioctl(file, I2C_SLAVE, addr) < 0) {
-    /* ERROR HANDLING; you can check errno to see what went wrong */
-    printf("Error addressing i2c slave.");
-    exit(1);
-   }
-
-   // step 3: write command over I2c
-   __u8 reg = 0x10; /* Device register to access */
-   __s32 res;
-   char buf[10];
-   buf[0] = reg;
-   buf[1] = 0x07; // the most right bits represent 4 relays' state: for example 00001111 - means all ON
-                  // send as a hexadecimal number
-   buf[2] = 0x65; // seems irrelevant the value
-   if (write(file, buf, 3) != 3) {
-     /* ERROR HANDLING: i2c transaction failed */
-     printf("Error writing to i2c slave."); 
-   }
-
-   printf("OK\n");
-   return 0;
-}

coupler/opc-ua-server/server.c

-/*
- * POC OPC-UA server based on https://github.com/open62541
+/* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
+ * See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */
+
+/**
+ * Adding Variables to a Server
+ * ----------------------------
+ *
+ * This tutorial shows how to work with data types and how to add variable nodes
+ * to a server. First, we add a new variable to the server. Take a look at the
+ * definition of the ``UA_VariableAttributes`` structure to see the list of all
+ * attributes defined for VariableNodes.
+ *
+ * Note that the default settings have the AccessLevel of the variable value as
+ * read only. See below for making the variable writable.
  */
+
+// Example controling MOD-IO's relays' state 
+// Based on https://www.kernel.org/doc/Documentation/i2c/dev-interface
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <linux/i2c-dev.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <signal.h>
+
 #include <open62541/plugin/log_stdout.h>
 #include <open62541/server.h>
 #include <open62541/server_config_default.h>
 
-#include <signal.h>
-#include <stdlib.h>
+// relays
+static int setRelayState(int command) {
+    // Set relays' state over I2C
+    int file;
+    int adapter_nr = 1; /* probably dynamically determined */
+    char filename[20];
+
+    // step 1: open device
+    snprintf(filename, 19, "/dev/i2c-%d", adapter_nr);
+    file = open(filename, O_RDWR);
+    if (file < 0) {
+        /* ERROR HANDLING; you can check errno to see what went wrong */
+        printf("Error openind i2c device.");
+        exit(1);
+    }
+
+    // step 2: address the slave by its address 
+    int addr = 0x58; /* The I2C address */
+    if (ioctl(file, I2C_SLAVE, addr) < 0) {
+        /* ERROR HANDLING; you can check errno to see what went wrong */
+        printf("Error addressing i2c slave.");
+        exit(1);
+    }
+
+    // step 3: write command over I2c
+    __u8 reg = 0x10; /* Device register to access */
+    __s32 res;
+    char buf[10];
+    buf[0] = reg;
+    buf[1] = command; //0x00 -all off, 0x0F - all 4 on
+    buf[2] = 0x65; // seems irrelevant the value
+    if (write(file, buf, 3) != 3) {
+        /* ERROR HANDLING: i2c transaction failed */
+        printf("Error writing to i2c slave."); 
+    }
+}
+
+static void
+addVariable(UA_Server *server) {
+    /* Define the attribute of the myInteger variable node */
+    UA_VariableAttributes attr = UA_VariableAttributes_default;
+    UA_Int32 myInteger = 42;
+    UA_Variant_setScalar(&attr.value, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
+    attr.description = UA_LOCALIZEDTEXT("en-US","the answer");
+    attr.displayName = UA_LOCALIZEDTEXT("en-US","the answer");
+    attr.dataType = UA_TYPES[UA_TYPES_INT32].typeId;
+    attr.accessLevel = UA_ACCESSLEVELMASK_READ | UA_ACCESSLEVELMASK_WRITE;
+
+    /* Add the variable node to the information model */
+    UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
+    UA_QualifiedName myIntegerName = UA_QUALIFIEDNAME(1, "the answer");
+    UA_NodeId parentNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER);
+    UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_ORGANIZES);
+    UA_Server_addVariableNode(server, myIntegerNodeId, parentNodeId,
+                              parentReferenceNodeId, myIntegerName,
+                              UA_NODEID_NUMERIC(0, UA_NS0ID_BASEDATAVARIABLETYPE), attr, NULL, NULL);
+}
+
+static void
+addMatrixVariable(UA_Server *server) {
+    UA_VariableAttributes attr = UA_VariableAttributes_default;
+    attr.displayName = UA_LOCALIZEDTEXT("en-US", "Double Matrix");
+    attr.accessLevel = UA_ACCESSLEVELMASK_READ | UA_ACCESSLEVELMASK_WRITE;
+
+    /* Set the variable value constraints */
+    attr.dataType = UA_TYPES[UA_TYPES_DOUBLE].typeId;
+    attr.valueRank = UA_VALUERANK_TWO_DIMENSIONS;
+    UA_UInt32 arrayDims[2] = {2,2};
+    attr.arrayDimensions = arrayDims;
+    attr.arrayDimensionsSize = 2;
+
+    /* Set the value. The array dimensions need to be the same for the value. */
+    UA_Double zero[4] = {0.0, 0.0, 0.0, 0.0};
+    UA_Variant_setArray(&attr.value, zero, 4, &UA_TYPES[UA_TYPES_DOUBLE]);
+    attr.value.arrayDimensions = arrayDims;
+    attr.value.arrayDimensionsSize = 2;
+
+    UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "double.matrix");
+    UA_QualifiedName myIntegerName = UA_QUALIFIEDNAME(1, "double matrix");
+    UA_NodeId parentNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER);
+    UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_ORGANIZES);
+    UA_Server_addVariableNode(server, myIntegerNodeId, parentNodeId,
+                              parentReferenceNodeId, myIntegerName,
+                              UA_NODEID_NUMERIC(0, UA_NS0ID_BASEDATAVARIABLETYPE),
+                              attr, NULL, NULL);
+}
+
+/**
+ * Now we change the value with the write service. This uses the same service
+ * implementation that can also be reached over the network by an OPC UA client.
+ */
+
+static void
+writeVariable(UA_Server *server) {
+    UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
+
+    /* Write a different integer value */
+    UA_Int32 myInteger = 43;
+    UA_Variant myVar;
+    UA_Variant_init(&myVar);
+    UA_Variant_setScalar(&myVar, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
+    UA_Server_writeValue(server, myIntegerNodeId, myVar);
+
+    /* Set the status code of the value to an error code. The function
+     * UA_Server_write provides access to the raw service. The above
+     * UA_Server_writeValue is syntactic sugar for writing a specific node
+     * attribute with the write service. */
+    UA_WriteValue wv;
+    UA_WriteValue_init(&wv);
+    wv.nodeId = myIntegerNodeId;
+    wv.attributeId = UA_ATTRIBUTEID_VALUE;
+    wv.value.status = UA_STATUSCODE_BADNOTCONNECTED;
+    wv.value.hasStatus = true;
+    UA_Server_write(server, &wv);
+
+    /* Reset the variable to a good statuscode with a value */
+    wv.value.hasStatus = false;
+    wv.value.value = myVar;
+    wv.value.hasValue = true;
+    UA_Server_write(server, &wv);
+}
+
+/**
+ * Note how we initially set the DataType attribute of the variable node to the
+ * NodeId of the Int32 data type. This forbids writing values that are not an
+ * Int32. The following code shows how this consistency check is performed for
+ * every write.
+ */
+
+static void
+writeWrongVariable(UA_Server *server) {
+    UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
+
+    /* Write a string */
+    UA_String myString = UA_STRING("test");
+    UA_Variant myVar;
+    UA_Variant_init(&myVar);
+    UA_Variant_setScalar(&myVar, &myString, &UA_TYPES[UA_TYPES_STRING]);
+    UA_StatusCode retval = UA_Server_writeValue(server, myIntegerNodeId, myVar);
+    printf("Writing a string returned statuscode %s\n", UA_StatusCode_name(retval));
+}
+
+/** It follows the main server code, making use of the above definitions. */
 
 static volatile UA_Boolean running = true;
-static void stopHandler(int sig) {
-    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "received ctrl-c");
+static void stopHandler(int sign) {
+    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "received ctrl-c");
     running = false;
 }
 
 int main(void) {
+    
+    // switch on all relays 
+    setRelayState(0x0F);
+    printf("Relays ON.\n");
+
+    // wait 1s 
+    sleep(1);
+
+    // switch off all relays
+    setRelayState(0x00);
+    printf("Relays OFF.\n");
+
     signal(SIGINT, stopHandler);
     signal(SIGTERM, stopHandler);
 
     UA_Server *server = UA_Server_new();
     UA_ServerConfig_setDefault(UA_Server_getConfig(server));
+    UA_ServerConfig* config = UA_Server_getConfig(server);
+    config->verifyRequestTimestamp = UA_RULEHANDLING_ACCEPT;
+#ifdef UA_ENABLE_WEBSOCKET_SERVER
+    UA_ServerConfig_addNetworkLayerWS(UA_Server_getConfig(server), 7681, 0, 0, NULL, NULL);
+#endif
+
+    addVariable(server);
+    addMatrixVariable(server);
+    writeVariable(server);
+    writeWrongVariable(server);
 
     UA_StatusCode retval = UA_Server_run(server, &running);