nodejs - 如何使用node-opcua訪問遠程opc服務器？

Question

我在github上找到了一個比較好的項目node-opcua，使用這個項目的簡單例子可以創建一個opc服務器和客戶端，並且在本地可以訪問，我現在需要訪問一個遠程opc服務器，提供幾個參數：IP網絡節點（如10.195.156.150），opc服務（例如ArchestrA。FSGateway），opc組（如ArchestrA），opc TagName（例如HXi1_P201_00。Ia），我可以使用node-opcua來訪問它嗎？ 謝謝！

sample_server代碼：

var opcua = require("node-opcua"); 
var os = require("os"); 

// Let's create an instance of OPCUAServer 
var server = new opcua.OPCUAServer({port: 4334}); 
var siteName = 'site01'; 

var var1 = {nodeId: 'ns=4;s=hook_weight', browseName: 'hook_weight', dataType: 'Double'}; 
var var2 = {nodeId: 'ns=4;s=rpm', browseName: 'rpm', dataType: 'Double'}; 
var var3 = {nodeId: 'ns=1;s=free_memory', browseName: 'free_memory', dataType: 'Double'}; 

function post_initialize(){ 
    console.log("server initialized"); 
    function construct_my_address_space(server) { 
     server.engine.createFolder("RootFolder",{ browseName: siteName}); 
     // emulate variable1 changing every 500 ms 
     var variable1 = 1; 
     setInterval(function(){ variable1 += 1; }, 1000); 

     var1.value = { 
      get: function(){ 
      return new opcua.Variant({dataType: opcua.DataType.Double, value: variable1 }); 
      } 
     }; 
     server.var1 = server.engine.addVariableInFolder(siteName, var1); 

     var2.value = { 
      get: function(){ 
      return new opcua.Variant({dataType: opcua.DataType.Double, value: 10}); 
      } 
     }; 
     server.var2 = server.engine.addVariableInFolder(siteName, var2); 

     /** 
     /** 
     * returns the percentage of free memory on the running machine 
     * @return {double} 
     */ 
     function available_memory() { 
      // var value = process.memoryUsage().heapUsed/1000000; 
      var percentageMemUsed = os.freemem()/os.totalmem() * 100.0; 
      return percentageMemUsed; 
     } 
     var3.value = { 
      get: function(){ 
      return new opcua.Variant({dataType: opcua.DataType.Double, value: available_memory()}); 
      } 
     }; 
     server.var3 = server.engine.addVariableInFolder(siteName, var3); 

    } 

    construct_my_address_space(server); 

    server.start(function() { 
     console.log("Server is now listening ... (press CTRL+C to stop)"); 
     console.log("port ", server.endpoints[0].port); 
     var endpointUrl = server.endpoints[0].endpointDescription().endpointUrl; 
     console.log(" the primary server endpoint url is ", endpointUrl); 
    }); 
} 
server.initialize(post_initialize); 

sample_client代碼：

var opcua = require("node-opcua"); 
var async = require("async"); 

var client = new opcua.OPCUAClient(); 
var endpointUrl = "opc.tcp://" + require("os").hostname().toLowerCase() + ":4334/UA/SampleServer"; 

var session, subscription; 

async.series([ 
    // step 1 : connect to 
    function(callback) { 
     client.connect(endpointUrl,function (err) { 
      if(err) { console.log(" cannot connect to endpoint :" , endpointUrl); } 
      else { console.log("connected !"); } 
      callback(err); 
     }); 
    }, 

    // step 2 : createSession 
    function(callback) { 
     client.createSession(function(err, _session) { 
      if(!err) { session = _session; } 
      callback(err); 
     }); 
    }, 

    // step 5: install a subscription and install a monitored item for 10 seconds 
    function(callback) { 
     subscription=new opcua.ClientSubscription(session,{ 
      requestedPublishingInterval: 1000, 
      requestedLifetimeCount: 10, 
      requestedMaxKeepAliveCount: 2, 
      maxNotificationsPerPublish: 10, 
      publishingEnabled: true, 
      priority: 10 
     }); 

     subscription.on("started",function(){ 
     console.log("subscriptionId=", subscription.subscriptionId); 
     }).on("keepalive",function(){ console.log(); }) 
     .on("terminated",function(){ callback(); }); 

     setTimeout(function() { 
       subscription.terminate(); 
     }, 10000); 

     // install monitored item 
     var monitoredItem = subscription.monitor({ 
       nodeId: opcua.resolveNodeId("ns=1;s=free_memory"), 
       attributeId: opcua.AttributeIds.Value 
      }, 
      { 
       samplingInterval: 100, 
       discardOldest: true, 
       queueSize: 100 
      }, 
      opcua.read_service.TimestampsToReturn.Both 
     ); 
     console.log("-------------------------------------"); 

     monitoredItem.on("changed", function (dataValue) { 
      console.log(" % free mem = ", dataValue.value.value); 
     }); 
    }, 

    // close session 
    function (callback) { 
     // _"closing session" 

     session.close(function (err) { 
      if (err) { 
       console.log("session closed failed ?"); 
      } 
      callback(); 
     }); 
    } 
], 
function(err) { 
    if (err) { console.log(" failure ",err); } 
    else { console.log('done!'); } 
    client.disconnect(function(){}); 
}); 

Answer 1

恐怕的ArchestrA沒有一個OPC UA服務器，所以從節點opcua訪問它，您將需要使用OPC UA網關，例如https://www.prosysopc.com/products/opc-ua-gateway/，它可以將OPC DA轉換爲OPC UA。