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

.NET

// This example shows how to subscribe to changes of a single monitored item and display the value of the item with each
// change.

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

namespace UADocExamples._EasyUAClient
{
    partial class SubscribeDataChange
    {
        public static void Overload1()
        {
            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/"

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

            Console.WriteLine("Subscribing...");
            client.SubscribeDataChange(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853", 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);

            Console.WriteLine("Finished.");
        }

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

# This example shows how to subscribe to changes of a single monitored item and display the value of the item with each
# change.

#requires -Version 5.1
using namespace OpcLabs.EasyOpc.UA

# The path below assumes that the current directory is [ProductDir]/Examples-NET/PowerShell/Windows .
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcUA.dll"
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcUAComponents.dll"

[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/"

# Instantiate the client object.
$client = New-Object EasyUAClient

# Data change notification handler
Register-ObjectEvent -InputObject $client -EventName DataChangeNotification -Action { 
    # Display value.
    if ($EventArgs.Succeeded) {
        Write-Host "Value: $($EventArgs.AttributeData.Value)"
    }
    else {
        Write-Host "*** Failure: $($EventArgs.ErrorMessageBrief)"
    }
}

Write-Host "Subscribing..."
$client.SubscribeDataChange($endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853", 1000)

Write-Host "Processing data change events for 20 seconds..."
$stopwatch =  [System.Diagnostics.Stopwatch]::StartNew() 
while ($stopwatch.Elapsed.TotalSeconds -lt 20) {    
    Start-Sleep -Seconds 1
}

Write-Host "Unsubscribing..."
$client.UnsubscribeAllMonitoredItems()

Write-Host "Waiting for 5 seconds..."
Start-Sleep -Seconds 5

Write-Host "Finished."

# This example shows how to subscribe to changes of a single monitored item and display the value of the item with each
# change.

# 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='')


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/'

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

print('Subscribing...')
IEasyUAClientExtension.SubscribeDataChange(client,
    endpointDescriptor,
    UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10853'),
    1000)

print('Processing data change events for 20 seconds...')
time.sleep(20)

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

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

print('Finished.')

' This example shows how to subscribe to changes of a single monitored item and display the value of the item with each change.

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

Namespace _EasyUAClient
    Friend Class SubscribeDataChange
        Public Shared Sub Overload1()

            ' 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/"

            ' Instantiate the client object and hook events
            Dim client = New EasyUAClient()
            AddHandler client.DataChangeNotification, AddressOf client_DataChangeNotification

            Console.WriteLine("Subscribing...")
            client.SubscribeDataChange(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853", 1000)

            Console.WriteLine("Processing monitored item changed events for 10 seconds...")
            Threading.Thread.Sleep(10 * 1000)

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

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

        Private Shared Sub client_DataChangeNotification(ByVal sender As Object, ByVal 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
        End Sub
    End Class
End Namespace

COM

// This example shows how to subscribe to changes of a single monitored item and display each change.

#include "stdafx.h"    // Includes "QuickOpc.h", and other commonly used files
#include <atlcom.h>
#include "SubscribeDataChange.h"

namespace _EasyUAClient
{
    // CEasyUAClientEvents

    class CEasyUAClientEvents : public IDispEventImpl<1, CEasyUAClientEvents>
    {
    public:
    BEGIN_SINK_MAP(CEasyUAClientEvents)
        // Event handlers must have the __stdcall calling convention
        SINK_ENTRY(1, DISPID_EASYUACLIENTEVENTS_DATACHANGENOTIFICATION, &CEasyUAClientEvents::DataChangeNotification)
    END_SINK_MAP()

    public:
        // The handler for EasyUAClient.DataChangeNotification event
        STDMETHOD(DataChangeNotification)(VARIANT varSender, _EasyUADataChangeNotificationEventArgs* pEventArgs)
        {
            // Display the data
            // Remark: Production code would check EventArgsPtr->Exception before accessing EventArgsPtr->AttributeData.
            _UAAttributeDataPtr AttributeDataPtr(pEventArgs->AttributeData);
            _tprintf(_T("%s\n"), (LPCTSTR)CW2CT(AttributeDataPtr->ToString));

            return S_OK;
        }
    };



    void SubscribeDataChange::Main()
    {
        // Initialize the COM library
        CoInitializeEx(NULL, COINIT_MULTITHREADED);
        {
            // Instantiate the client object
            _EasyUAClientPtr ClientPtr(__uuidof(EasyUAClient));

            // Hook events
            CEasyUAClientEvents* pClientEvents = new CEasyUAClientEvents();
            AtlGetObjectSourceInterface(ClientPtr, &pClientEvents->m_libid, &pClientEvents->m_iid, 
                &pClientEvents->m_wMajorVerNum, &pClientEvents->m_wMinorVerNum);
            pClientEvents->m_iid = _uuidof(DEasyUAClientEvents);
            pClientEvents->DispEventAdvise(ClientPtr, &pClientEvents->m_iid);

            //
            _tprintf(_T("Subscribing...\n"));
            ClientPtr->SubscribeDataChange(
                //L"http://opcua.demo-this.com:51211/UA/SampleServer", 
                L"opc.tcp://opcua.demo-this.com:51210/UA/SampleServer",
                L"nsu=http://test.org/UA/Data/ ;i=10853",
                1000);

            _tprintf(_T("Processing monitored item changed events for 1 minute...\n"));
            Sleep(60*1000);

            // Unhook events
            pClientEvents->DispEventUnadvise(ClientPtr, &pClientEvents->m_iid);
        }
         // Release all interface pointers BEFORE calling CoUninitialize()
        CoUninitialize();
    }
}

// This example shows how to subscribe to changes of a single monitored item
// and display each change.

type
  TClientEventHandlers = class
    procedure OnDataChangeNotification(
      Sender: TObject;
      sender0: OleVariant;
      eventArgs: _EasyUADataChangeNotificationEventArgs);
  end;

procedure TClientEventHandlers.OnDataChangeNotification(
  Sender: TObject;
  sender0: OleVariant;
  eventArgs: _EasyUADataChangeNotificationEventArgs);
begin
  // Display the data
  // Remark: Production code would check eventArgs.Exception before accessing
  // eventArgs.AttributeData.
    WriteLn(eventArgs.Arguments.NodeDescriptor.ToString, ': ',
    eventArgs.AttributeData.ToString);
end;

class procedure SubscribeDataChange.Main;
var
  Client: EasyUAClient;
  EvsClient: TEvsEasyUAClient;
  ClientEventHandlers: TClientEventHandlers;
begin
  // Instantiate the client object and hook events
  EvsClient := TEvsEasyUAClient.Create(nil);
  Client := EvsClient.ComServer;
  ClientEventHandlers := TClientEventHandlers.Create;
  EvsClient.OnDataChangeNotification := @ClientEventHandlers.OnDataChangeNotification;

  WriteLn('Subscribing...');
  Client.SubscribeDataChange(
    //'http://opcua.demo-this.com:51211/UA/SampleServer',
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer',
    'nsu=http://test.org/UA/Data/ ;i=10853',
    1000);

  WriteLn('Processing data change events for 1 minute...');
  PumpSleep(60*1000);
end;

// This example shows how to subscribe to changes of a single monitored item
// and display each change.

type
  TClientEventHandlers121 = class
    procedure OnDataChangeNotification(
      ASender: TObject;
      sender: OleVariant;
      const eventArgs: _EasyUADataChangeNotificationEventArgs);
  end;

procedure TClientEventHandlers121.OnDataChangeNotification(
  ASender: TObject;
  sender: OleVariant;
  const eventArgs: _EasyUADataChangeNotificationEventArgs);
begin
  // Display the data
  if eventArgs.Succeeded then
      WriteLn(eventArgs.Arguments.NodeDescriptor.ToString, ': ',
      eventArgs.AttributeData.ToString)
  else
      WriteLn(eventArgs.Arguments.NodeDescriptor.ToString, ' *** Failure: ',
      eventArgs.ErrorMessageBrief);
end;

class procedure SubscribeDataChange.Main;
var
  Client: TEasyUAClient;
  ClientEventHandlers: TClientEventHandlers121;
begin
  // Instantiate the client object and hook events
  Client := TEasyUAClient.Create(nil);
  ClientEventHandlers := TClientEventHandlers121.Create;
  Client.OnDataChangeNotification := ClientEventHandlers.OnDataChangeNotification;

  WriteLn('Subscribing...');
  Client.SubscribeDataChange(
      //'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',
    'nsu=http://test.org/UA/Data/ ;i=10853',
    1000);

  WriteLn('Processing data change events for 1 minute...');
  PumpSleep(60*1000);

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

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

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

// This example shows how to subscribe to changes of a single monitored item and display each change.

class ClientEvents {
    function DataChangeNotification($Sender, $E)
    {
        // Display the data
        if ($E->Succeeded)
        printf("%s\n", $E->AttributeData);
        else
        printf("*** Failure : %s\n", $E->ErrorMessageBrief);
    }
}



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

printf("Subscribing...\n");
$Client->SubscribeDataChange(
    //"http://opcua.demo-this.com:51211/UA/SampleServer", 
    "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", 
   "nsu=http://test.org/UA/Data/ ;i=10853", 
    1000);

printf("Processing monitored item changed events for 1 minute...\n");
$startTime = time(); do { com_message_pump(1000); } while (time() < $startTime + 60);

Rem This example shows how to subscribe to changes of a single monitored item and display each change.

' The client object, with events
'Public WithEvents Client1 As EasyUAClient

Public Sub SubscribeDataChange_Main_Command_Click()
    OutputText = ""
    
    Set Client1 = New EasyUAClient

    OutputText = OutputText & "Subscribing..." & vbCrLf
    Call Client1.SubscribeDataChange("opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/ ;i=10853", 1000)

    OutputText = OutputText & "Processing data changed notification events for 1 minute..." & vbCrLf
    Pause 60000

    OutputText = OutputText & "Unsubscribing..." & vbCrLf
    Client1.UnsubscribeAllMonitoredItems

    OutputText = OutputText & "Waiting for 5 seconds..." & vbCrLf
    Pause 5000

    OutputText = OutputText & "Finished." & vbCrLf
    Set Client1 = Nothing
End Sub

Public Sub Client1_DataChangeNotification(ByVal sender As Variant, ByVal eventArgs As EasyUADataChangeNotificationEventArgs)
    ' Display the data
    If eventArgs.Exception Is Nothing Then
        OutputText = OutputText & eventArgs.AttributeData & vbCrLf
    Else
        OutputText = OutputText & eventArgs.ErrorMessageBrief & vbCrLf
    End If
End Sub

Rem This example shows how to subscribe to changes of a single monitored item and display each change.

Option Explicit

' Instantiate the client object and hook events
Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient")
WScript.ConnectObject Client, "Client_"

WScript.Echo "Subscribing..."
Client.SubscribeDataChange "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer", "nsu=http://test.org/UA/Data/ ;i=10853", 1000

WScript.Echo "Processing monitored item changed events for 1 minute..."
WScript.Sleep 60*1000



Sub Client_DataChangeNotification(Sender, e)
    ' Display the data
    Dim display: If e.Exception Is Nothing Then display = e.AttributeData Else display = e.ErrorMessageBrief
    WScript.Echo display
End Sub

.NET

COM

Conceptual

Examples - OPC Data Access

Examples - OPC UA Alarms&Conditions

Examples - OPC UA Interaction

Examples - OPC UA Layered Extensions