OPC Studio User's Guide and Reference
Examples - OPC UA Complex Data - Subscribe to data change

The example below shows how to subscribe to OPC UA complex data and display the incoming values.

.NET

// Shows how to subscribe to complex data with OPC UA Complex Data plug-in.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

using System;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples.ComplexData._EasyUAClient
{
    class SubscribeDataChange
    {
        public static void Main1()
        {
            // Define which server and node we will work with.
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"
            UANodeDescriptor nodeDescriptor =
                "nsu=http://test.org/UA/Data/ ;i=10867"; // [ObjectsFolder]/Data.Dynamic.Scalar.StructureValue

            // Instantiate the client object and hook the event handler.
            var client = new EasyUAClient();
            client.DataChangeNotification += client_DataChangeNotification;

            // Subscribe to a node which returns complex data. This is done in the same way as regular subscribes - just 
            // the data returned is different.
            Console.WriteLine("Subscribing...");
            client.SubscribeDataChange(endpointDescriptor, nodeDescriptor, samplingInterval:1000);

            Console.WriteLine("Processing data change events for 20 seconds...");
            System.Threading.Thread.Sleep(20 * 1000);

            Console.WriteLine("Unsubscribing...");
            client.UnsubscribeAllMonitoredItems();

            Console.WriteLine("Waiting for 5 seconds...");
            System.Threading.Thread.Sleep(5 * 1000);

            // Unhook the event handler.
            client.DataChangeNotification -= client_DataChangeNotification;


            // Example output:
            //
            //Subscribing...
            //Processing data change events for 20 seconds...
            //(ScalarValueDataType) structured
            //(ArrayValueDataType) structured
            //(ArrayValueDataType) structured
            //(ArrayValueDataType) structured
            //(ArrayValueDataType) structured
            //(ArrayValueDataType) structured
            //(ArrayValueDataType) structured
            //(ArrayValueDataType) structured
            //(ScalarValueDataType) structured
            //(ScalarValueDataType) structured
            //(ArrayValueDataType) structured
            //(ArrayValueDataType) structured
            //(ScalarValueDataType) structured
            //(ArrayValueDataType) structured
            //(ArrayValueDataType) structured
            //(ScalarValueDataType) structured
            //(ScalarValueDataType) structured
            //(ScalarValueDataType) structured
            //Unsubscribing...
            //Waiting for 5 seconds...
        }

        static void client_DataChangeNotification(object sender, EasyUADataChangeNotificationEventArgs e)
        {
            // Display value
            if (e.Succeeded)
                Console.WriteLine("Value: {0}", e.AttributeData.Value);
            else
                Console.WriteLine("*** Failure: {0}", e.ErrorMessageBrief);

            // For processing the internals of the data, refer to examples for GenericData and DataType classes.
        }
    }
}

# Shows how to subscribe to complex data with OPC UA Complex Data plug-in.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import time

# Import .NET namespaces.
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.OperationModel import *


def dataChangeNotification(sender, e):
    # Display value.
    if e.Succeeded:
        print('Value: ', e.AttributeData.Value, sep='')
    else:
        print('*** Failure: ', e.ErrorMessageBrief, sep='')
    #
    # For processing the internals of the data, refer to examples for GenericData and DataType classes.


endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer')
# or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported)
# or 'https://opcua.demo-this.com:51212/UA/SampleServer/'

# [ObjectsFolder]/Data.Dynamic.Scalar.StructureValue
nodeDescriptor = UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10867')

# Instantiate the client object and hook events.
client = EasyUAClient()
client.DataChangeNotification += dataChangeNotification

# Subscribe to a node which returns complex data. This is done in the same way as regular subscribes - just
# the data returned is different.
print('Subscribing...')
IEasyUAClientExtension.SubscribeDataChange(client,
    endpointDescriptor,
    nodeDescriptor,
    1000)   # samplingInterval

print('Processing data change events for 30 seconds...')
time.sleep(30)

print('Unsubscribing...')
client.UnsubscribeAllMonitoredItems()

print('Waiting for 5 seconds...')
time.sleep(5)

# Unhook the event handler.
client.DataChangeNotification -= dataChangeNotification

print('Finished.')

' Shows how to subscribe to complex data with OPC UA Complex Data plug-in.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

Imports System
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace ComplexData._EasyUAClient

    Friend Class SubscribeDataChange

        Public Shared Sub Main1()

            ' Define which server we will work with.
            Dim endpointDescriptor As UAEndpointDescriptor =
                    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
            ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            ' or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            ' Define which node we will work with.
            Dim nodeDescriptor As UANodeDescriptor = _
                "nsu=http://test.org/UA/Data/ ;i=10867"  ' [ObjectsFolder]/Data.Dynamic.Scalar.StructureValue

            ' Instantiate the client object and hook the event handler.
            Dim client = New EasyUAClient
            AddHandler client.DataChangeNotification, AddressOf client_DataChangeNotification

            ' Subscribe to a node which returns complex data. This is done in the same way as regular subscribes - just 
            ' the data returned is different.
            Console.WriteLine("Subscribing...")
            client.SubscribeDataChange(endpointDescriptor, nodeDescriptor, samplingInterval:=1000)

            Console.WriteLine("Processing data change events for 20 seconds...")
            Threading.Thread.Sleep((20 * 1000))

            Console.WriteLine("Unsubscribing...")
            client.UnsubscribeAllMonitoredItems()

            Console.WriteLine("Waiting for 5 seconds...")
            Threading.Thread.Sleep((5 * 1000))

            ' Unhook the event handler.
            RemoveHandler client.DataChangeNotification, AddressOf client_DataChangeNotification


            ' Example output:
            '
            'Subscribing...
            'Processing data change events for 20 seconds...
            '(ScalarValueDataType) structured
            '(ArrayValueDataType) structured
            '(ArrayValueDataType) structured
            '(ArrayValueDataType) structured
            '(ArrayValueDataType) structured
            '(ArrayValueDataType) structured
            '(ArrayValueDataType) structured
            '(ArrayValueDataType) structured
            '(ScalarValueDataType) structured
            '(ScalarValueDataType) structured
            '(ArrayValueDataType) structured
            '(ArrayValueDataType) structured
            '(ScalarValueDataType) structured
            '(ArrayValueDataType) structured
            '(ArrayValueDataType) structured
            '(ScalarValueDataType) structured
            '(ScalarValueDataType) structured
            '(ScalarValueDataType) structured
            'Unsubscribing...
            'Waiting for 5 seconds...
        End Sub

        Private Shared Sub client_DataChangeNotification(sender As Object, e As EasyUADataChangeNotificationEventArgs)
            ' Display value
            If e.Succeeded Then
                Console.WriteLine("Value: {0}", e.AttributeData.Value)
            Else
                Console.WriteLine("*** Failure: {0}", e.ErrorMessageBrief)
            End If

            ' For processing the internals of the data, refer to examples for GenericData and DataType classes.
        End Sub
    End Class
End Namespace

COM

// Shows how to subscribe to complex data with OPC UA Complex Data plug-in.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

type
  TClientEventHandlers33 = class
    procedure OnDataChangeNotification(
      ASender: TObject;
      sender: OleVariant;
      const eventArgs: _EasyUADataChangeNotificationEventArgs);
  end;

procedure TClientEventHandlers33.OnDataChangeNotification(
  ASender: TObject;
  sender: OleVariant;
  const eventArgs: _EasyUADataChangeNotificationEventArgs);
begin
  // Display value
  if eventArgs.Succeeded then
      WriteLn('Value: ', eventArgs.AttributeData.Value.ToString)
  else
      WriteLn('*** Failure: ', eventArgs.ErrorMessageBrief);

  // For processing the internals of the data, refer to examples for GenericData and DataType classes.
end;

class procedure SubscribeDataChange.Main;
var
  Client: TEasyUAClient;
  ClientEventHandlers: TClientEventHandlers33;
  EndpointDescriptor: string;
  NodeDescriptor: string;
begin
  // Define which server and node we will work with.
  EndpointDescriptor := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  NodeDescriptor := 'nsu=http://test.org/UA/Data/ ;i=10867';  // [ObjectsFolder]/Data.Dynamic.Scalar.StructureValue

  // Instantiate the client object and hook events
  Client := TEasyUAClient.Create(nil);
  ClientEventHandlers := TClientEventHandlers33.Create;
  Client.OnDataChangeNotification := ClientEventHandlers.OnDataChangeNotification;

  // Subscribe to a node which returns complex data. This is done in the same way as regular subscribes - just
  // the data returned is different.
  WriteLn('Subscribing...');
  Client.SubscribeDataChange(EndpointDescriptor, NodeDescriptor, 1000);

  WriteLn('Processing data change events for 20 seconds...');
  PumpSleep(20*1000);

  WriteLn('Unsubscribing...');
  Client.UnsubscribeAllMonitoredItems;

  WriteLn('Waiting for 5 seconds...');
  PumpSleep(5*1000);

  WriteLn('Finished.');
  FreeAndNil(Client);
  FreeAndNil(ClientEventHandlers);

  // Example output:
  //
  //Subscribing...
  //Processing data change events for 20 seconds...
  //(ScalarValueDataType) structured
  //(ArrayValueDataType) structured
  //(ArrayValueDataType) structured
  //(ArrayValueDataType) structured
  //(ArrayValueDataType) structured
  //(ArrayValueDataType) structured
  //(ArrayValueDataType) structured
  //(ArrayValueDataType) structured
  //(ScalarValueDataType) structured
  //(ScalarValueDataType) structured
  //(ArrayValueDataType) structured
  //(ArrayValueDataType) structured
  //(ScalarValueDataType) structured
  //(ArrayValueDataType) structured
  //(ArrayValueDataType) structured
  //(ScalarValueDataType) structured
  //(ScalarValueDataType) structured
  //(ScalarValueDataType) structured
  //Unsubscribing...
  //Waiting for 5 seconds...
end;

// Shows how to subscribe to complex data with OPC UA Complex Data plug-in.
//
// Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

class ClientEvents {
    function DataChangeNotification($Sender, $E)
    {
        // Display value
        if ($E->Succeeded)
        printf("Value: %s\n", $E->AttributeData->Value);
        else
        printf("*** Failure : %s\n", $E->ErrorMessageBrief);
        // For processing the internals of the data, refer to examples for GenericData and DataType classes.
    }
}

// Define which server and node we will work with.
$EndpointDescriptor = 
    //"http://opcua.demo-this.com:51211/UA/SampleServer";
    //"https://opcua.demo-this.com:51212/UA/SampleServer/";
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
$NodeDescriptor = "nsu=http://test.org/UA/Data/ ;i=10867";  // [ObjectsFolder]/Data.Dynamic.Scalar.StructureValue

// Instantiate the client object and hook events
$Client = new COM("OpcLabs.EasyOpc.UA.EasyUAClient");
$ClientEvents = new ClientEvents();
com_event_sink($Client, $ClientEvents, "DEasyUAClientEvents");

// Subscribe to a node which returns complex data. This is done in the same way as regular subscribes - just
// the data returned is different.
printf("Subscribing...\n");
$Client->SubscribeDataChange($EndpointDescriptor, $NodeDescriptor, 1000);

printf("Processing data change events for 20 seconds...\n");
$startTime = time(); do { com_message_pump(1000); } while (time() < $startTime + 20);

printf("Unsubscribing...\n");
$Client->UnsubscribeAllMonitoredItems;

printf("Waiting for 5 seconds...\n");
$startTime = time(); do { com_message_pump(1000); } while (time() < $startTime + 5);

 

See Also
Examples - OPC UA Complex Data - Read a value
Examples - OPC UA Complex Data - Process generic data

Conceptual

OPC UA Complex Data subscribing

Examples - OPC Unified Architecture

Examples - OPC Unified Architecture - Subscribe to a single node for data changes

 

 

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