基于open62541的opc ua 服务器开发实现（1）

时间：2024-09-08 14:06:26

关于opcua的介绍这里就不多说了，相信大家大都有了一些了解，open62541是一个开源C（C99）的opc-ua实现，开源代码可在官网或github上下载。

话不多说，首先搭建一个opcua服务器实例

 #include <signal.h>

 #include "open62541.h"

    UA_Boolean running = true;

    static void stopHandler(int sig)
      {

    UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND, "received ctrl-c");

    running = false;

    }

 int main(void) {

    signal(SIGINT, stopHandler);

    signal(SIGTERM, stopHandler);

    UA_ServerConfig *config = UA_ServerConfig_new_default();

    UA_Server *server = UA_Server_new(config);

    UA_StatusCode retval = UA_Server_run(server, &running);

    UA_Server_delete(server);

    UA_ServerConfig_delete(config);

    return (int)retval;

    }

以下代码演示如何使用数据类型以及如何向服务器添加变量节点。首先，我们向服务器添加一个新变量。查看UA变量属性结构的定义，以查看为变量节点定义的所有属性的列表。请注意，默认设置将变量值的访问级别设置为只读。有关使变量可写的信息，请参见下文。

 #include <signal.h>

 #include <stdio.h>

 #include "open62541.h"

 static void

 addVariable(UA_Server *server) {

    /* Define the attribute of the myInteger variable node */

    UA_VariableAttributes attr = UA_VariableAttributes_default;

    UA_Int32 myInteger = ;

    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(, "the.answer");

    UA_QualifiedName myIntegerName = UA_QUALIFIEDNAME(, "the answer");

    UA_NodeId parentNodeId = UA_NODEID_NUMERIC(, UA_NS0ID_OBJECTSFOLDER);

    UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(, UA_NS0ID_ORGANIZES);

    UA_Server_addVariableNode(server, myIntegerNodeId, parentNodeId,

    parentReferenceNodeId, myIntegerName,

    UA_NODEID_NUMERIC(, UA_NS0ID_BASEDATAVARIABLETYPE),attr, NULL, NULL);

    }

现在我们用 写服务 更改节点值。也可以通过网络由OPC UA的客户端访问来修改值 。

 static void

 writeVariable(UA_Server *server) {

     UA_NodeId myIntegerNodeId =

     UA_NODEID_STRING(,"the.answer");

     /* Write a different integer value */

     UA_Int32 myInteger = ;

     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);

     }

注意我们最初如何将变量节点的data type属性设置为int32数据类型的nodeid。这禁止写入非Int32的值。下面的代码显示了如何对每次写入执行一致性检查。

 static void

 writeWrongVariable(UA_Server *server) {

    UA_NodeId myIntegerNodeId = UA_NODEID_STRING(, "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));

    }

它遵循主服务器代码，使用上述定义。

 UA_Boolean running = true;

 static void stopHandler(int sign) {

 UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "received ctrl-c");

 running = false;

 }

 int main(void) {

    signal(SIGINT, stopHandler);

    signal(SIGTERM, stopHandler);

    UA_ServerConfig *config = UA_ServerConfig_new_default();

    UA_Server *server = UA_Server_new(config);

    addVariable(server);

    writeVariable(server);

    writeWrongVariable(server);

    UA_StatusCode retval = UA_Server_run(server, &running);

    UA_Server_delete(server);

    UA_ServerConfig_delete(config);

    return (int)retval;

    }

在基于OPC UA的体系结构中，服务器通常位于信息源附近。在工业环境中，这意味着服务器接近物理过程，客户机在运行时使用数据。在前面的教程中，我们看到了如何向OPC UA信息模型添加变量。本实例演示如何将变量连接到运行时信息，例如从物理过程的测量中连接。为简单起见，我们以系统时钟为基础的“过程”。以下代码段分别与运行时更新变量值的不同方式有关。总之，代码片段定义了一个可编译的源文件。

作为起点，假设已在服务器中为datetime类型的值创建了一个标识符为“ns=1，s=current time”的变量。假设当一个新的值从底层进程到达时，我们的应用程序被触发，我们可以直接写入变量。

 #include <signal.h>

 #include "open62541.h"

 #pragma comment(lib, "WS2_32")

 static void

 updateCurrentTime(UA_Server *server) {

     UA_DateTime now = UA_DateTime_now();

     UA_Variant value;

     UA_Variant_setScalar(&value, &now, &UA_TYPES[UA_TYPES_DATETIME]);

     UA_NodeId currentNodeId = UA_NODEID_STRING(, "current-time");

     UA_Server_writeValue(server, currentNodeId, value);

 }

 static void

 addCurrentTimeVariable(UA_Server *server) {

     UA_DateTime now = ;

     UA_VariableAttributes attr = UA_VariableAttributes_default;

     attr.displayName = UA_LOCALIZEDTEXT("en-US", "Current time");

     attr.accessLevel = UA_ACCESSLEVELMASK_READ | UA_ACCESSLEVELMASK_WRITE;

     UA_Variant_setScalar(&attr.value, &now, &UA_TYPES[UA_TYPES_DATETIME]);

     UA_NodeId currentNodeId = UA_NODEID_STRING(, "current-time");

     UA_QualifiedName currentName = UA_QUALIFIEDNAME(, "current-time");

     UA_NodeId parentNodeId = UA_NODEID_NUMERIC(, UA_NS0ID_OBJECTSFOLDER);

     UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(, UA_NS0ID_ORGANIZES);

     UA_NodeId variableTypeNodeId = UA_NODEID_NUMERIC(, UA_NS0ID_BASEDATAVARIABLETYPE);

     UA_Server_addVariableNode(server, currentNodeId, parentNodeId,

         parentReferenceNodeId, currentName,

         variableTypeNodeId, attr, NULL, NULL);

     updateCurrentTime(server);

 }

2.值回调

当一个值不断变化时，例如系统时间，在一个紧密的循环中更新该值将占用大量的资源。值回调允许将变量值与外部表示同步。它们将回调附加到每次读操作之前和每次写操作之后执行的变量。

 static void

 beforeReadTime(UA_Server *server,

     const UA_NodeId *sessionId, void *sessionContext,

     const UA_NodeId *nodeid, void *nodeContext,

     const UA_NumericRange *range, const UA_DataValue *data) {

     UA_DateTime now = UA_DateTime_now();

     UA_Variant value;

     UA_Variant_setScalar(&value, &now, &UA_TYPES[UA_TYPES_DATETIME]);

     UA_NodeId currentNodeId = UA_NODEID_STRING(, "current-time");

     UA_Server_writeValue(server, currentNodeId, value);

 }

 static void

 afterWriteTime(UA_Server *server,

     const UA_NodeId *sessionId, void *sessionContext,

     const UA_NodeId *nodeId, void *nodeContext,

     const UA_NumericRange *range, const UA_DataValue *data) {

     UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_USERLAND,

         "The variable was updated");

 }

 static void

 addValueCallbackToCurrentTimeVariable(UA_Server *server) {

     UA_NodeId currentNodeId = UA_NODEID_STRING(, "current-time");

     UA_ValueCallback callback;

     callback.onRead = beforeReadTime;

     callback.onWrite = afterWriteTime;

     UA_Server_setVariableNode_valueCallback(server, currentNodeId, callback);

 }

3.变量数据源

对于值回调，该值仍存储在变量节点中。所谓的数据源更进一步。服务器将每个读写请求重定向到回调函数。在读取时，回调提供当前值的副本。在内部，数据源需要实现自己的内存管理。

 static UA_StatusCode

 readCurrentTime(UA_Server *server,

     const UA_NodeId *sessionId, void *sessionContext,

     const UA_NodeId *nodeId, void *nodeContext,

     UA_Boolean sourceTimeStamp, const UA_NumericRange *range,

     UA_DataValue *dataValue) {

     UA_DateTime now = UA_DateTime_now();

     UA_Variant_setScalarCopy(&dataValue->value, &now,

         &UA_TYPES[UA_TYPES_DATETIME]);

     dataValue->hasValue = true;

     return UA_STATUSCODE_GOOD;

 }

 static UA_StatusCode

 writeCurrentTime(UA_Server *server,

     const UA_NodeId *sessionId, void *sessionContext,

     const UA_NodeId *nodeId, void *nodeContext,

     const UA_NumericRange *range, const UA_DataValue *data) {

     UA_LOG_INFO(UA_Log_out, UA_LOGCATEGORY_USERLAND,

         "Changing the system time is not implemented");

     return UA_STATUSCODE_GOOD;

 }

 static void

 addCurrentTimeDataSourceVariable(UA_Server *server) {

     UA_VariableAttributes attr = UA_VariableAttributes_default;

     attr.displayName = UA_LOCALIZEDTEXT("en-US", "Current time - data source");

     attr.accessLevel = UA_ACCESSLEVELMASK_READ | UA_ACCESSLEVELMASK_WRITE;

     UA_NodeId currentNodeId = UA_NODEID_STRING(, "current-time-datasource");

     UA_QualifiedName currentName = UA_QUALIFIEDNAME(, "current-time-datasource");

     UA_NodeId parentNodeId = UA_NODEID_NUMERIC(, UA_NS0ID_OBJECTSFOLDER);

     UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(, UA_NS0ID_ORGANIZES);

     UA_NodeId variableTypeNodeId = UA_NODEID_NUMERIC(, UA_NS0ID_BASEDATAVARIABLETYPE);

     UA_DataSource timeDataSource;

     timeDataSource.read = readCurrentTime;

     timeDataSource.write = writeCurrentTime;

     UA_Server_addDataSourceVariableNode(server, currentNodeId, parentNodeId,

         parentReferenceNodeId, currentName,

         variableTypeNodeId, attr,

         timeDataSource, NULL, NULL);

 }

以下代码遵循主服务器代码，使用上述定义。

 UA_Boolean running = true;

 static void stopHandler(int sign) {

     UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "received ctrl-c");

     running = false;

 }

 int main(void) {

     signal(SIGINT, stopHandler);

     signal(SIGTERM, stopHandler);

     UA_ServerConfig *config = UA_ServerConfig_new_default();

     UA_Server *server = UA_Server_new(config);

     addCurrentTimeVariable(server);

     addValueCallbackToCurrentTimeVariable(server);

     addCurrentTimeDataSourceVariable(server);

     UA_StatusCode retval = UA_Server_run(server, &running);

     UA_Server_delete(server);

     UA_ServerConfig_delete(config);

     return (int)retval;

 }

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