Isolated Property (_EasyDAClient)

Specifies that you wish that the OpcLabs.EasyOpc.DataAccess.EasyDAClientCore object instance works with an "isolated" connection to the OPC server, i.e. one that is not shared with other instances.

Syntax

bool Isolated {get; set;}

property bool Isolated {
   bool get();
   void set (    bool value);
}

'Declaration
 
Property Isolated As Boolean

'Usage
 
Dim instance As _EasyDAClient
Dim value As Boolean
 
instance.Isolated = value
 
value = instance.Isolated

Remarks

This member or type is for use from COM. It is not meant to be used from .NET or Python. Refer to the corresponding .NET member or type instead, if you are developing in .NET or Python.

This method or property does not throw any exceptions, aside from execution exceptions such as System.Threading.ThreadAbortException or System.OutOfMemoryException.

Example

// This example shows how to create and use two isolated client objects, resulting in two separate connections to the target
// OPC DA server.
//
// 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.Diagnostics;
using System.Threading;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.DataAccess.OperationModel;

namespace DocExamples.DataAccess._EasyDAClient
{
    class Isolated
    {
        public static void Main1()
        {
            // Instantiate the client objects and make them isolated
            var client1 = new EasyDAClient { Isolated = true };
            var client2 = new EasyDAClient { Isolated = true };

            // The callback is a local method the displays the value
            void ItemChangedCallback(object sender, EasyDAItemChangedEventArgs eventArgs)
            {
                Debug.Assert(!(eventArgs is null));

                string displayPrefix = $"[{eventArgs.Arguments.State}]";
                if (eventArgs.Succeeded)
                {
                    Debug.Assert(!(eventArgs.Vtq is null));
                    Console.WriteLine($"{displayPrefix} {eventArgs.Vtq}");
                }
                else
                    Console.WriteLine($"{displayPrefix} *** Failure: {eventArgs.ErrorMessageBrief}");
            }

            Console.WriteLine("Subscribing...");
            client1.SubscribeItem("", "OPCLabs.KitServer.2", "Simulation.Random", 1000, ItemChangedCallback, state: 1);
            client2.SubscribeItem("", "OPCLabs.KitServer.2", "Simulation.Random", 1000, ItemChangedCallback, state: 2);

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

            Console.WriteLine("Unsubscribing...");
            client1.UnsubscribeAllItems();
            client2.UnsubscribeAllItems();

            Console.WriteLine("Waiting for 2 seconds...");
            Thread.Sleep(2 * 1000);
        }
    }
}

' This example shows how to create and use two isolated client objects, resulting in two separate connections to the target
' OPC DA server.
'
' 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 OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.DataAccess.OperationModel

Namespace DataAccess._EasyDAClient
    Partial Friend Class Isolated
        Shared Sub Main1()
            ' Instantiate the client objects and make them isolated
            Dim client1 As New EasyDAClient() With {.Isolated = True}
            Dim client2 As New EasyDAClient() With {.Isolated = True}

            ' The callback is a local method the displays the value
            Dim ItemChagedCallback = Sub(sender As Object, eventArgs As EasyDAItemChangedEventArgs)
                                         Debug.Assert(eventArgs IsNot Nothing)

                                         Dim displayPrefix As String = $"[{eventArgs.Arguments.State}]"
                                         If eventArgs.Succeeded Then
                                             Debug.Assert(eventArgs.Vtq IsNot Nothing)
                                             Console.WriteLine($"{displayPrefix} {eventArgs.Vtq}")
                                         Else
                                             Console.WriteLine($"{displayPrefix} *** Failure: {eventArgs.ErrorMessageBrief}")
                                         End If
                                     End Sub

            Console.WriteLine("Subscribing...")
            client1.SubscribeItem("", "OPCLabs.KitServer.2", "Simulation.Random", 1000, ItemChagedCallback, state:=1)
            client2.SubscribeItem("", "OPCLabs.KitServer.2", "Simulation.Random", 1000, ItemChagedCallback, state:=2)

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

            Console.WriteLine("Unsubscribing...")
            client1.UnsubscribeAllItems()
            client2.UnsubscribeAllItems()

            Console.WriteLine("Waiting for 2 seconds...")
            Threading.Thread.Sleep(2 * 1000)
        End Sub
    End Class
End Namespace

# This example shows how to create and use two isolated client objects, resulting in two separate connections to the
# target OPC DA server.
#
# 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 *


# Item changed event handler
def itemChangedCallback(sender, eventArgs):
    assert eventArgs is not None
    displayPrefix = '[{}]'.format(eventArgs.Arguments.State)
    if eventArgs.Succeeded:
        assert eventArgs.Vtq is not None
        print(displayPrefix + ' ' + eventArgs.Vtq.ToString() + '\n', end='')
    else:
        print(displayPrefix + ' *** Failure: ' + eventArgs.ErrorMessageBrief + '\n', end='')


# Instantiate the client objects and make them isolated.
client1 = EasyDAClient()
client1.Isolated = True
client2 = EasyDAClient()
client2.Isolated = True

print('Subscribing item changes...')
IEasyDAClientExtension.SubscribeItem(client1,
                                     '', 'OPCLabs.KitServer.2', 'Simulation.Random', 1000,
                                     EasyDAItemChangedEventHandler(itemChangedCallback), 1)
IEasyDAClientExtension.SubscribeItem(client2,
                                     '', 'OPCLabs.KitServer.2', 'Simulation.Random', 1000,
                                     EasyDAItemChangedEventHandler(itemChangedCallback), 2)

print('Processing item change notifications for 10 seconds...')
time.sleep(10)

print('Unsubscribing all items...')
client1.UnsubscribeAllItems()
client2.UnsubscribeAllItems()

print('Waiting for 2 seconds...')
time.sleep(2)

print('Finished.')

Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

Reference

_EasyDAClient Interface
_EasyDAClient Members

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Missing some example? Ask us for it on our Online Forums! You do not have to own a commercial license in order to use Online Forums, and we reply to every post.