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.

The value of this parameter cannot be null (Nothing in Visual Basic).

The individual elements of the parameter value cannot be null (Nothing in Visual Basic).

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 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.

Example

COM

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 .
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_"

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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