学习open62541 --- [69] Client监测多个变量值

有读者问Client如何监测多个变量值，这篇文章给了提示，但是没给例子，本文给出详细例子，使用的open62541版本是1.3.3， 运行环境debian10.5。

一 准备Server

首先准备一个server，然后添加2个变量，再加个定时任务来修改这2个变量的值，代码如下，

// server.c

#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>

#include "open62541.h"

UA_Boolean running = true;

void stopHandler(int sign) {
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "received ctrl-c");
    running = false;
}



UA_NodeId addTheAnswerVariable(UA_Server *server) 
{
    /* Define the attribute of the myInteger variable node */
    UA_VariableAttributes attr = UA_VariableAttributes_default;
    UA_Int32 myInteger = 1;
    UA_Variant_setScalar(&attr.value, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
    attr.description = UA_LOCALIZEDTEXT((char*)"en-US", (char*)"the answer");
    attr.displayName = UA_LOCALIZEDTEXT((char*)"en-US", (char*)"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 theAnswerNodeId = UA_NODEID_STRING(1, (char*)"the.answer");
    UA_QualifiedName myIntegerName = UA_QUALIFIEDNAME(1, (char*)"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, theAnswerNodeId, parentNodeId,
                              parentReferenceNodeId, myIntegerName,
                              UA_NODEID_NUMERIC(0, UA_NS0ID_BASEDATAVARIABLETYPE), attr, NULL, NULL);
    
    return theAnswerNodeId;
}

UA_NodeId addTheAnswer2Variable(UA_Server *server) 
{
    /* Define the attribute of the myInteger variable node */
    UA_VariableAttributes attr = UA_VariableAttributes_default;
    UA_Int32 myInteger = 1;
    UA_Variant_setScalar(&attr.value, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
    attr.description = UA_LOCALIZEDTEXT((char*)"en-US", (char*)"the answer2");
    attr.displayName = UA_LOCALIZEDTEXT((char*)"en-US", (char*)"the answer2");
    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 theAnswerNodeId = UA_NODEID_STRING(1, (char*)"the.answer2");
    UA_QualifiedName myIntegerName = UA_QUALIFIEDNAME(1, (char*)"the answer2");
    UA_NodeId parentNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER);
    UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_ORGANIZES);
    UA_Server_addVariableNode(server, theAnswerNodeId, parentNodeId,
                              parentReferenceNodeId, myIntegerName,
                              UA_NODEID_NUMERIC(0, UA_NS0ID_BASEDATAVARIABLETYPE), attr, NULL, NULL);
    
    return theAnswerNodeId;
}

void cycleCallback(UA_Server *server, void *data) 
{
    static UA_Int32 update = 2;
    static UA_Int32 update2 = 8;
        
    UA_NodeId * idArray = (UA_NodeId*)data;

    UA_Variant myVar;
    UA_Variant_init(&myVar);
    UA_Variant_setScalar(&myVar, &update, &UA_TYPES[UA_TYPES_INT32]);
    UA_Server_writeValue(server, idArray[0], myVar);

    UA_Variant_init(&myVar);
    UA_Variant_setScalar(&myVar, &update2, &UA_TYPES[UA_TYPES_INT32]);
    UA_Server_writeValue(server, idArray[1], myVar);
    
    update++;
    update2++;
    
    if (update == 100)
    {
        update = 2;
    }

    if (update2 == 200)
    {
        update = 8;
    }
}


int main(void) 
{    
    signal(SIGINT, stopHandler);
    signal(SIGTERM, stopHandler);

    UA_Server *server = UA_Server_new();
    UA_ServerConfig_setDefault(UA_Server_getConfig(server));
    
    UA_NodeId targetNodeId = addTheAnswerVariable(server);
    UA_NodeId target2NodeId = addTheAnswer2Variable(server);

    UA_NodeId idArr[2] = {targetNodeId, target2NodeId};

    UA_UInt64 callbackId = 0;
	UA_Server_addRepeatedCallback(server, cycleCallback, idArr, 2000, &callbackId); // call every 2s
    
  
    UA_StatusCode retval = UA_Server_run(server, &running);
    
    UA_Server_delete(server);
    
    return retval == UA_STATUSCODE_GOOD ? EXIT_SUCCESS : EXIT_FAILURE;
}

这里使用了定时接口来做修改任务。

二 Client代码

代码如下，

#include <stdlib.h>
#include <signal.h>
#include "open62541.h"


UA_Boolean running = true;


UA_NodeId idArr[2] = {UA_NODEID_STRING(1, (char*)"the.answer"), UA_NODEID_STRING(1, (char*)"the.answer2")};

void stopHandler(int sign) {
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "received ctrl-c");
    running = false;
}


static void handler_DataChanged(UA_Client *client, UA_UInt32 subId, 
                                    void *subContext, UA_UInt32 monId, 
                                    void *monContext, UA_DataValue *value) 
{
    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_CLIENT, "Received Notification");

    UA_NodeId *ptr = (UA_NodeId*)monContext;

    if (UA_NodeId_equal(ptr, &idArr[0]))
    {
        UA_Int32 currentValue = *(UA_Int32*)(value->value.data);
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_CLIENT, "SubId:%u, MonId:%u, Current Value: %d\n", 
                                                            subId, monId, currentValue);
    }
    else if (UA_NodeId_equal(ptr, &idArr[1]))
    {
        UA_Int32 currentValue = *(UA_Int32*)(value->value.data);
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_CLIENT, "SubId:%u, MonId:%u, Current Value: %d\n", 
                                                            subId, monId, currentValue);
    }
}




void addMonitoredItemToVariable(UA_Client *client)
{
    /* Create a subscription */
    UA_CreateSubscriptionRequest request = UA_CreateSubscriptionRequest_default();
    UA_CreateSubscriptionResponse response = UA_Client_Subscriptions_create(client, request,
                                                                            NULL, NULL, NULL);

    UA_UInt32 subId = response.subscriptionId;
    if(response.responseHeader.serviceResult == UA_STATUSCODE_GOOD)
    {
        UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_CLIENT, "Create subscription succeeded, id %u\n", subId);
    }

    
	UA_MonitoredItemCreateRequest items[2];
    UA_UInt32 newMonitoredItemIds[2];
    UA_Client_DataChangeNotificationCallback callbacks[2];
    UA_Client_DeleteMonitoredItemCallback deleteCallbacks[2];
    void *contexts[2];

    /* monitor "ths answer" */
    items[0] = UA_MonitoredItemCreateRequest_default(idArr[0]);
    callbacks[0] = handler_DataChanged;
    contexts[0] = &idArr[0];
    deleteCallbacks[0] = NULL;

    /* monitor "the answer2" */
    items[1] = UA_MonitoredItemCreateRequest_default(idArr[1]);
    callbacks[1] = handler_DataChanged;
    contexts[1] = &idArr[1];
    deleteCallbacks[1] = NULL;


    UA_CreateMonitoredItemsRequest createRequest;
    UA_CreateMonitoredItemsRequest_init(&createRequest);
    createRequest.subscriptionId = subId;
    createRequest.timestampsToReturn = UA_TIMESTAMPSTORETURN_BOTH;
    createRequest.itemsToCreate = items;
    createRequest.itemsToCreateSize = 2;
    UA_CreateMonitoredItemsResponse createResponse =
       UA_Client_MonitoredItems_createDataChanges(client, createRequest, contexts,
                                                   callbacks, deleteCallbacks);


	for (uint32_t i = 0; i < createResponse.resultsSize; ++i)
	{
		if (createResponse.results->statusCode != UA_STATUSCODE_GOOD)
		{
			printf("==> error\n");
		}
	}

}

int main(void) 
{
    signal(SIGINT, stopHandler);
    signal(SIGTERM, stopHandler);


    UA_Client *client = UA_Client_new();
    UA_ClientConfig_setDefault(UA_Client_getConfig(client));
    UA_StatusCode retval = UA_Client_connect(client, "opc.tcp://localhost:4840");
    if(retval != UA_STATUSCODE_GOOD) 
    {
        UA_Client_delete(client);
        return (int)retval;
    }

    addMonitoredItemToVariable(client);

    while(running)
    {
        // send publish request, time out 1000ms
        UA_Client_run_iterate(client, 1000); 
    }

    UA_Client_delete(client); /* Disconnects the client internally */
    
    return EXIT_SUCCESS;
}

关键部分在addMonitoredItemToVariable()里，其实也比较简单，就是挨个赋值，2个监测项都使用相同的回调函数，里面会判断节点的nodeid，注意代码里使用了一个全局数组idArr来保存目标id。

三 运行

如何编译不再赘述，最后运行如下，

可以看到MonId是不同的，说明监测成功！