ChangeMultipleItemSubscriptions Method (

Changes parameters of subscriptions to multiple OPC items.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
Sub ChangeMultipleItemSubscriptions( _
   ByVal argumentsArray As Object _
)

'Usage
 
Dim instance As _EasyDAClient
Dim argumentsArray As Object
 
instance.ChangeMultipleItemSubscriptions(argumentsArray)

void ChangeMultipleItemSubscriptions( 
   object argumentsArray
)

void ChangeMultipleItemSubscriptions( 
   Object^ argumentsArray
)

Parameters

argumentsArray: Array of arguments, one element per each OPC item involved in the operation.

Exceptions

Exception Description

Exception	Description
System.ArgumentException	One of the arguments provided to a method is not valid. This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.
System.ArgumentNullException	A `null` reference (`Nothing` in Visual Basic) is passed to a method that does not accept it as a valid argument. This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

System.ArgumentException

One of the arguments provided to a method is not valid.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

System.ArgumentNullException

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

Remarks

The user-defined state, as given in OpcLabs.BaseLib.OperationModel.OperationArguments.State property of OpcLabs.EasyOpc.DataAccess.OperationModel.EasyDAItemSubscriptionArguments when subscribing to the item, cannot be changed. The OpcLabs.BaseLib.OperationModel.OperationArguments.State property of OpcLabs.EasyOpc.DataAccess.OperationModel.DAHandleGroupArguments in the OpcLabs.EasyOpc.DataAccess.IEasyDAClient.ChangeMultipleItemSubscriptions method call is not used.

When you use this method, the OpcLabs.EasyOpc.DataAccess.OperationModel.EasyDAItemChangedEventArgs.Arguments in the event notifications and callbacks may, during the transition period, correspond to an improper (older or newer) value.

This method operates (at least in part) asynchronously, with respect to the caller. The actual execution of the operation may be delayed, and the outcome of the operation (if any) is provided to the calling code using an event notification, callback, or other means explained in the text. In a properly written program, this method does not throw any exceptions. You should therefore not put try/catch statements or similar constructs around calls to this method. The only exceptions thrown by this method are for usage errors, i.e. when your code violates the usage contract of the method, such as passing in invalid arguments or calling the method when the state of the object does not allow it. Any operation-related errors (i.e. errors that depend on external conditions that your code cannot reliably check) are indicated by the means the operation returns its outcome (if any), which is described in the text. For more information, see Do not catch any exceptions with asynchronous or multiple-operation methods.

Example

.NET

// This example shows how change the update rate of multiple existing subscriptions.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

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

                Console.WriteLine("Subscribing...");
                int[] handleArray = 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("Waiting for 10 seconds...");
                Thread.Sleep(10 * 1000);

                Console.WriteLine("Changing subscriptions...");
                client.ChangeMultipleItemSubscriptions(new[]
                {
                    new DAHandleGroupArguments(handleArray[0], 100),
                    new DAHandleGroupArguments(handleArray[1], 100)
                });

                Console.WriteLine("Waiting for 10 seconds...");
                Thread.Sleep(10 * 1000);

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

                Console.WriteLine("Waiting for 10 seconds...");
                Thread.Sleep(10 * 1000);
            }
        }

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

# This example shows how change the update rate of multiple existing subscriptions.
#
# 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.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...')
handleArray = 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 10 seconds...')
time.sleep(10)

print('Changing item subscriptions...')
client.ChangeMultipleItemSubscriptions([
    DAHandleGroupArguments(handleArray[0], 100),
    DAHandleGroupArguments(handleArray[1], 100),
    ])

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

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

print('Waiting for 10 seconds...')
time.sleep(10)

client.ItemChanged -= itemChanged

print('Finished.')

' This example shows how change the update rate of multiple existing subscriptions.
'
' Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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

Namespace DataAccess._EasyDAClient

    Partial Friend Class ChangeMultipleItemSubscriptions
        Public Shared Sub Main1()
            Using client = New EasyDAClient()
                AddHandler client.ItemChanged, AddressOf client_ItemChanged

                Console.WriteLine("Subscribing...")
                Dim handle As Integer = client.SubscribeItem("", "OPCLabs.KitServer.2", "Simulation.Random", 1000)
                Dim handleArray() As Integer = 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("Waiting for 10 seconds...")
                Thread.Sleep(10 * 1000)

                Console.WriteLine("Changing subscription...")
                client.ChangeMultipleItemSubscriptions(New DAHandleGroupArguments() {
                    New DAHandleGroupArguments(handleArray(0), 100),
                    New DAHandleGroupArguments(handleArray(1), 100)
                })

                Console.WriteLine("Waiting for 10 seconds...")
                Thread.Sleep(10 * 1000)

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

                Console.WriteLine("Waiting for 10 seconds...")
                Thread.Sleep(10 * 1000)
            End Using
        End Sub

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

VBScript

Rem This example shows how change the update rate of multiple existing subscriptions.
Rem
Rem Find all latest examples here : https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .

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_"

WScript.Echo "Subscribing..."
Dim handleArray: handleArray = Client.SubscribeMultipleItems(arguments)

WScript.Echo "Waiting for 10 seconds..."
WScript.Sleep 10*1000

WScript.Echo "Changing subscriptions..."

Dim HandleGroupArguments1: Set HandleGroupArguments1 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAHandleGroupArguments")
HandleGroupArguments1.Handle = handleArray(0)
HandleGroupArguments1.GroupParameters.RequestedUpdateRate = 100

Dim HandleGroupArguments2: Set HandleGroupArguments2 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAHandleGroupArguments")
HandleGroupArguments2.Handle = handleArray(1)
HandleGroupArguments2.GroupParameters.RequestedUpdateRate = 100

Dim subscriptionChangeArguments(1)
Set subscriptionChangeArguments(0) = HandleGroupArguments1
Set subscriptionChangeArguments(1) = HandleGroupArguments2

Client.ChangeMultipleItemSubscriptions subscriptionChangeArguments

WScript.Echo "Waiting for 10 seconds..."
WScript.Sleep 10*1000

WScript.Echo "Unsubscribing..."
Client.UnsubscribeAllItems

WScript.Echo "Waiting for 10 seconds..."
WScript.Sleep 10*1000

WScript.DisconnectObject Client
Set Client = Nothing



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

    WScript.Echo e.Vtq
End Sub

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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