OPC Studio User's Guide and Reference
Examples - OPC Data Access - Subscribe to multiple items

.NET

// This example shows how subscribe to changes of multiple items and display the value of the item with each change.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-CSharp .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

using System;
using System.Threading;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.DataAccess.OperationModel;

namespace DocExamples.DataAccess._EasyDAClient
{
    partial class SubscribeMultipleItems
    {
        public static void Main1()
        {
            // Instantiate the client object.
            using (var client = new EasyDAClient())
            {
                client.ItemChanged += client_Main1_ItemChanged;

                Console.WriteLine("Subscribing item changes...");
                client.SubscribeMultipleItems(
                    new[] {
                            new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Simulation.Random", 1000, null), 
                            new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Ramp (1 min)", 1000, null), 
                            new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Sine (1 min)", 1000, null),  
                            new DAItemGroupArguments("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 1000, null)
                        });

                Console.WriteLine("Processing item changed events for 1 minute...");
                Thread.Sleep(60 * 1000);

                Console.WriteLine("Unsubscribing item changes...");
            }

            Console.WriteLine("Finished.");
        }

        // Item changed event handler
        static void client_Main1_ItemChanged(object sender, EasyDAItemChangedEventArgs e)
        {
            if (e.Succeeded)
                Console.WriteLine($"{e.Arguments.ItemDescriptor.ItemId}: {e.Vtq}");
            else
                Console.WriteLine($"{e.Arguments.ItemDescriptor.ItemId} *** Failure: {e.ErrorMessageBrief}");
        }
    }
}

# This example shows how subscribe to changes of multiple items and display the value of the item with each change.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in PowerShell on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PowerShell .
# Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
# a commercial license in order to use Online Forums, and we reply to every post.

#requires -Version 5.1
using namespace OpcLabs.EasyOpc.DataAccess
using namespace OpcLabs.EasyOpc.DataAccess.OperationModel

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

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

# Item changed event handler
Register-ObjectEvent -InputObject $client -EventName ItemChanged -Action { 
    if ($EventArgs.Succeeded) {
        Write-Host "$($EventArgs.Arguments.ItemDescriptor.ItemId): $($EventArgs.Vtq)"
    }
    else {
        Write-Host "$($EventArgs.Arguments.ItemDescriptor.ItemId) *** Failure: $($EventArgs.ErrorMessageBrief)"
    }
}

Write-Host "Subscribing item changes..."
$handleArray = [IEasyDAClientExtension]::SubscribeMultipleItems($client, @(
    (New-Object DAItemGroupArguments("", "OPCLabs.KitServer.2", "Simulation.Random", 1000, $null)),
    (New-Object DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Ramp (1 min)", 1000, $null)),
    (New-Object DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Sine (1 min)", 1000, $null)),
    (New-Object DAItemGroupArguments("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 1000, $null))
    ))

Write-Host "Processing item changed events for 1 minute..."
$stopwatch =  [System.Diagnostics.Stopwatch]::StartNew() 
while ($stopwatch.Elapsed.TotalSeconds -lt 30) {    
    Start-Sleep -Seconds 1
}

Write-Host "Unsubscribing item changes..."
$client.UnsubscribeAllItems()

Write-Host "Finished."

' This example shows how subscribe to changes of multiple items and display the value of the item with each change.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
' OPC client and subscriber examples in VB.NET on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBNET .
' Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
' a commercial license in order to use Online Forums, and we reply to every post.

Imports System.Threading
Imports OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.DataAccess.OperationModel

Namespace DataAccess._EasyDAClient
    Partial Friend Class SubscribeMultipleItems
        Public Shared Sub Main1()
            Using client = New EasyDAClient()
                AddHandler client.ItemChanged, AddressOf client_ItemChanged_Main1

                client.SubscribeMultipleItems(New DAItemGroupArguments() { _
                 New DAItemGroupArguments("", "OPCLabs.KitServer.2", "Simulation.Random", 1000, Nothing), _
                 New DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Ramp (1 min)", 1000, Nothing), _
                 New DAItemGroupArguments("", "OPCLabs.KitServer.2", "Trends.Sine (1 min)", 1000, Nothing), _
                 New DAItemGroupArguments("", "OPCLabs.KitServer.2", "Simulation.Register_I4", 1000, Nothing) _
                })

                Console.WriteLine("Processing item changed events for 1 minute...")
                Thread.Sleep(60 * 1000)
            End Using
        End Sub

        ' Item changed event handler
        Private Shared Sub client_ItemChanged_Main1(ByVal sender As Object, ByVal e As EasyDAItemChangedEventArgs)
            ' Display the data
            If e.Succeeded Then
                Console.WriteLine("{0}: {1}", e.Arguments.ItemDescriptor.ItemId, e.Vtq)
            Else
                Console.WriteLine("{0} *** Failure: {1}", e.Arguments.ItemDescriptor.ItemId, e.ErrorMessageBrief)
            End If
        End Sub
    End Class
End Namespace

COM

// This example shows how to subscribe to changes of multiple items and display the value of the item with each change.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in PHP on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PHP .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

class DEasyDAClientEvents {
    function ItemChanged($varSender, $varE)
    {
        if ($varE->Succeeded)
        {
            printf("s: s\n", $varE->Arguments->ItemDescriptor->ItemId, $varE->Vtq->ToString());
        }
        else
        {
            printf("*** Failure: %s\n", $varE->ErrorMessageBrief);
        }
    }
}

$ItemSubscriptionArguments1 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.EasyDAItemSubscriptionArguments");
$ItemSubscriptionArguments1->ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";
$ItemSubscriptionArguments1->ItemDescriptor->ItemID = "Simulation.Random";
$ItemSubscriptionArguments1->GroupParameters->RequestedUpdateRate = 1000;

$ItemSubscriptionArguments2 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.EasyDAItemSubscriptionArguments");
$ItemSubscriptionArguments2->ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";
$ItemSubscriptionArguments2->ItemDescriptor->ItemID = "Trends.Ramp (1 min)";
$ItemSubscriptionArguments2->GroupParameters->RequestedUpdateRate = 1000;

$ItemSubscriptionArguments3 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.EasyDAItemSubscriptionArguments");
$ItemSubscriptionArguments3->ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";
$ItemSubscriptionArguments3->ItemDescriptor->ItemID = "Trends.Sine (1 min)";
$ItemSubscriptionArguments3->GroupParameters->RequestedUpdateRate = 1000;

$ItemSubscriptionArguments4 = new COM("OpcLabs.EasyOpc.DataAccess.OperationModel.EasyDAItemSubscriptionArguments");
$ItemSubscriptionArguments4->ServerDescriptor->ServerClass = "OPCLabs.KitServer.2";
$ItemSubscriptionArguments4->ItemDescriptor->ItemID = "Simulation.Register_I4";
$ItemSubscriptionArguments4->GroupParameters->RequestedUpdateRate = 1000;

$arguments[0] = $ItemSubscriptionArguments1;
$arguments[1] = $ItemSubscriptionArguments2;
$arguments[2] = $ItemSubscriptionArguments3;
$arguments[3] = $ItemSubscriptionArguments4;

$Client = new COM("OpcLabs.EasyOpc.DataAccess.EasyDAClient");
$Events = new DEasyDAClientEvents();
com_event_sink($Client, $Events, "DEasyDAClientEvents");

$Client->SubscribeMultipleItems($arguments);

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

// This example shows how to subscribe to changes of multiple items and display the value of the item with each change.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in Object Pascal (Delphi) on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-OP .
// Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
// a commercial license in order to use Online Forums, and we reply to every post.

type
  TSubscribeMultipleItems_ClientEventHandlers = class
    // Item changed event handler
    procedure OnItemChanged(
      ASender: TObject;
      sender: OleVariant;
      const eventArgs: _EasyDAItemChangedEventArgs);
  end;

procedure TSubscribeMultipleItems_ClientEventHandlers.OnItemChanged(
  ASender: TObject;
  sender: OleVariant;
  const eventArgs: _EasyDAItemChangedEventArgs);
begin
  if eventArgs.Succeeded then
    WriteLn(eventArgs.Arguments.ItemDescriptor.ItemId, ': ', eventArgs.Vtq.ToString)
  else
    WriteLn(eventArgs.Arguments.ItemDescriptor.ItemId, ' *** Failure: ', eventArgs.ErrorMessageBrief);
end;

class procedure SubscribeMultipleItems.Main;
var
  Arguments: OleVariant;
  Client: TEasyDAClient;
  ClientEventHandlers: TSubscribeMultipleItems_ClientEventHandlers;
  HandleArray: OleVariant;
  ItemSubscriptionArguments1: _EasyDAItemSubscriptionArguments;
  ItemSubscriptionArguments2: _EasyDAItemSubscriptionArguments;
  ItemSubscriptionArguments3: _EasyDAItemSubscriptionArguments;
  ItemSubscriptionArguments4: _EasyDAItemSubscriptionArguments;
begin
  ItemSubscriptionArguments1 := CoEasyDAItemSubscriptionArguments.Create;
  ItemSubscriptionArguments1.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2';
  ItemSubscriptionArguments1.ItemDescriptor.ItemID := 'Simulation.Random';
  ItemSubscriptionArguments1.GroupParameters.RequestedUpdateRate := 1000;

  ItemSubscriptionArguments2 := CoEasyDAItemSubscriptionArguments.Create;
  ItemSubscriptionArguments2.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2';
  ItemSubscriptionArguments2.ItemDescriptor.ItemID := 'Trends.Ramp (1 min)';
  ItemSubscriptionArguments2.GroupParameters.RequestedUpdateRate := 1000;

  ItemSubscriptionArguments3 := CoEasyDAItemSubscriptionArguments.Create;
  ItemSubscriptionArguments3.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2';
  ItemSubscriptionArguments3.ItemDescriptor.ItemID := 'Trends.Sine (1 min)';
  ItemSubscriptionArguments3.GroupParameters.RequestedUpdateRate := 1000;

  ItemSubscriptionArguments4 := CoEasyDAItemSubscriptionArguments.Create;
  ItemSubscriptionArguments4.ServerDescriptor.ServerClass := 'OPCLabs.KitServer.2';
  ItemSubscriptionArguments4.ItemDescriptor.ItemID := 'Simulation.Register_I4';
  ItemSubscriptionArguments4.GroupParameters.RequestedUpdateRate := 1000;

  Arguments := VarArrayCreate([0, 3], varVariant);
  Arguments[0] := ItemSubscriptionArguments1;
  Arguments[1] := ItemSubscriptionArguments2;
  Arguments[2] := ItemSubscriptionArguments3;
  Arguments[3] := ItemSubscriptionArguments4;

  // Instantiate the client object and hook events
  Client := TEasyDAClient.Create(nil);
  ClientEventHandlers := TSubscribeMultipleItems_ClientEventHandlers.Create;
  Client.OnItemChanged := ClientEventHandlers.OnItemChanged;

  TVarData(HandleArray).VType := varArray or varVariant;
  TVarData(HandleArray).VArray := PVarArray(
    Client.SubscribeMultipleItems(Arguments));

  WriteLn('Processing item changed events for 1 minute...');
  PumpSleep(60*1000);

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

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

  WriteLn('Finished.');
  VarClear(HandleArray);
  VarClear(Arguments);
  FreeAndNil(Client);
  FreeAndNil(ClientEventHandlers);
end;

REM This example shows how to subscribe to changes of multiple items and display the value of the item with each change.
REM
REM Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
REM OPC client and subscriber examples in Visual Basic on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VB .
REM Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
REM a commercial license in order to use Online Forums, and we reply to every post.

' The client object, with events
'Public WithEvents Client2 As EasyDAClient

Private Sub SubscribeMultipleItems_Main_Command_Click()
    OutputText = ""
    
    Dim itemSubscriptionArguments1 As New EasyDAItemSubscriptionArguments
    itemSubscriptionArguments1.serverDescriptor.ServerClass = "OPCLabs.KitServer.2"
    itemSubscriptionArguments1.ItemDescriptor.itemId = "Simulation.Random"
    itemSubscriptionArguments1.GroupParameters.requestedUpdateRate = 1000

    Dim itemSubscriptionArguments2 As New EasyDAItemSubscriptionArguments
    itemSubscriptionArguments2.serverDescriptor.ServerClass = "OPCLabs.KitServer.2"
    itemSubscriptionArguments2.ItemDescriptor.itemId = "Trends.Ramp (1 min)"
    itemSubscriptionArguments2.GroupParameters.requestedUpdateRate = 1000

    Dim itemSubscriptionArguments3 As New EasyDAItemSubscriptionArguments
    itemSubscriptionArguments3.serverDescriptor.ServerClass = "OPCLabs.KitServer.2"
    itemSubscriptionArguments3.ItemDescriptor.itemId = "Trends.Sine (1 min)"
    itemSubscriptionArguments3.GroupParameters.requestedUpdateRate = 1000

    ' Intentionally specifying an unknown item here, to demonstrate its behavior.
    Dim itemSubscriptionArguments4 As New EasyDAItemSubscriptionArguments
    itemSubscriptionArguments4.serverDescriptor.ServerClass = "OPCLabs.KitServer.2"
    itemSubscriptionArguments4.ItemDescriptor.itemId = "Simulation.Register_I4"
    itemSubscriptionArguments4.GroupParameters.requestedUpdateRate = 1000

    Dim arguments(3) As Variant
    Set arguments(0) = itemSubscriptionArguments1
    Set arguments(1) = itemSubscriptionArguments2
    Set arguments(2) = itemSubscriptionArguments3
    Set arguments(3) = itemSubscriptionArguments4

    ' Instantiate the client object
    Set Client2 = New EasyDAClient

    OutputText = OutputText & "Subscribing item changes..." & vbCrLf
    Dim handleArray() As Variant
    handleArray = Client2.SubscribeMultipleItems(arguments)
    
    OutputText = OutputText & "Processing item changed events for 1 minute..." & vbCrLf
    Pause 60000

    OutputText = OutputText & "Unsubscribing..." & vbCrLf
    Client2.UnsubscribeAllItems

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

    OutputText = OutputText & "Finished." & vbCrLf
    Set Client2 = Nothing
End Sub

Public Sub Client2_ItemChanged(ByVal sender As Variant, ByVal eventArgs As EasyDAItemChangedEventArgs)
    If eventArgs.Succeeded Then
        OutputText = OutputText & eventArgs.arguments.ItemDescriptor.itemId & ": " & eventArgs.vtq & vbCrLf
    Else
        OutputText = OutputText & eventArgs.arguments.ItemDescriptor.itemId & " *** Failure: " & eventArgs.ErrorMessageBrief & vbCrLf
    End If
End Sub

Rem This example shows how to subscribe to changes of multiple items and display the value of the item with each change.
Rem
Rem Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
Rem OPC client and subscriber examples in VBScript on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBScript .
Rem Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
Rem a commercial license in order to use Online Forums, and we reply to every post.

Option Explicit

Dim ItemSubscriptionArguments1: Set ItemSubscriptionArguments1 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.EasyDAItemSubscriptionArguments")
ItemSubscriptionArguments1.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ItemSubscriptionArguments1.ItemDescriptor.ItemID = "Simulation.Random"
ItemSubscriptionArguments1.GroupParameters.RequestedUpdateRate = 1000

Dim ItemSubscriptionArguments2: Set ItemSubscriptionArguments2 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.EasyDAItemSubscriptionArguments")
ItemSubscriptionArguments2.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ItemSubscriptionArguments2.ItemDescriptor.ItemID = "Trends.Ramp (1 min)"
ItemSubscriptionArguments2.GroupParameters.RequestedUpdateRate = 1000

Dim ItemSubscriptionArguments3: Set ItemSubscriptionArguments3 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.EasyDAItemSubscriptionArguments")
ItemSubscriptionArguments3.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ItemSubscriptionArguments3.ItemDescriptor.ItemID = "Trends.Sine (1 min)"
ItemSubscriptionArguments3.GroupParameters.RequestedUpdateRate = 1000

Dim ItemSubscriptionArguments4: Set ItemSubscriptionArguments4 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.EasyDAItemSubscriptionArguments")
ItemSubscriptionArguments4.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ItemSubscriptionArguments4.ItemDescriptor.ItemID = "Simulation.Register_I4"
ItemSubscriptionArguments4.GroupParameters.RequestedUpdateRate = 1000

Dim arguments(3)
Set arguments(0) = ItemSubscriptionArguments1
Set arguments(1) = ItemSubscriptionArguments2
Set arguments(2) = ItemSubscriptionArguments3
Set arguments(3) = ItemSubscriptionArguments4

Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
WScript.ConnectObject Client, "Client_"

Client.SubscribeMultipleItems arguments

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

Sub Client_ItemChanged(Sender, e)
    If Not (e.Succeeded) Then
        WScript.Echo "*** Failure: " & e.ErrorMessageBrief
        Exit Sub
    End If

    WScript.Echo e.Arguments.ItemDescriptor.ItemId & ": " & e.Vtq
End Sub

Python

# This example shows how subscribe to changes of multiple items and display the value of the item with each change.
#
# 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 .
# Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
# a commercial license in order to use Online Forums, and we reply to every post.
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import time

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


# Item changed event handler.
def itemChanged(sender, e):
    if e.Succeeded:
        print(e.Arguments.ItemDescriptor.ItemId, ': ', e.Vtq, sep='')
    else:
        print(e.Arguments.ItemDescriptor.ItemId, ' *** Failure: ', e.ErrorMessageBrief, sep='')


# Instantiate the client object.
client = EasyDAClient()

client.ItemChanged += itemChanged

print('Subscribing item changes...')
client.SubscribeMultipleItems([
    EasyDAItemSubscriptionArguments('', 'OPCLabs.KitServer.2', 'Simulation.Random', 1000, None),
    EasyDAItemSubscriptionArguments('', 'OPCLabs.KitServer.2', 'Trends.Ramp (1 min)', 1000, None),
    EasyDAItemSubscriptionArguments('', 'OPCLabs.KitServer.2', 'Trends.Sine (1 min)', 1000, None),
    EasyDAItemSubscriptionArguments('', 'OPCLabs.KitServer.2', 'Simulation.Register_I4', 1000, None),
    ])

print('Processing item change notifications for 1 minute...')
time.sleep(60)

print('Unsubscribing all items...')
client.UnsubscribeAllItems()

client.ItemChanged -= itemChanged

print('Finished.')

 

See Also
Examples - OPC Data Access - Subscribe to a single item
Examples - OPC Data Access - Unsubscribe from multiple items
Examples - OPC Data Access - Unsubscribe from all items
Examples - OPC Data Access - Read multiple items
Examples - OPC Data Access - Subscribe to items of various data types
Examples - OPC Data Access - Subscribe to large number of items
Examples - OPC Data Access - Identify subscriptions by an integer state
Examples - OPC Data Access - Identify subscriptions by an object state
Examples - OPC Data Access - Subscribe to multiple items with percent deadband
Examples - OPC Data Access - Subscribe to multiple items and keep state in dictionary
Examples - OPC Data Access - Subscribe to multiple items

Concepts

Subscribing to OPC Classic Items

Examples - Client OPC Unified Architecture

Examples - OPC Unified Architecture - Subscribe to multiple nodes for data changes

Examples - Client OPC Classic Specialized

Examples - OPC Classic Specialized - Schneider Electric OPC Factory Server - Subscribe to multiple items

 

 

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