EasyDAItemSubscriptionArguments Constructor(String,String,String,VarType,Int32,EasyDAItemChangedEventHandler,Object)

Initializes a new instance of the class. Initializes a new instance of the class, with the OPC server specified by machine name and server class, the OPC item specified by its ItemId and data type, the OPC group parameters specified by requested update rate, user-defined state object, and with a callback method.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
Public Function New( _
   ByVal machineName As String, _
   ByVal serverClass As String, _
   ByVal itemId As String, _
   ByVal dataType As VarType, _
   ByVal requestedUpdateRate As Integer, _
   ByVal callback As EasyDAItemChangedEventHandler, _
   ByVal state As Object _
)

'Usage
 
Dim machineName As String
Dim serverClass As String
Dim itemId As String
Dim dataType As VarType
Dim requestedUpdateRate As Integer
Dim callback As EasyDAItemChangedEventHandler
Dim state As Object
 
Dim instance As New EasyDAItemSubscriptionArguments(machineName, serverClass, itemId, dataType, requestedUpdateRate, callback, state)

public EasyDAItemSubscriptionArguments( 
   string machineName,
   string serverClass,
   string itemId,
   VarType dataType,
   int requestedUpdateRate,
   EasyDAItemChangedEventHandler callback,
   object state
)

public:
EasyDAItemSubscriptionArguments( 
   String^ machineName,
   String^ serverClass,
   String^ itemId,
   VarType^ dataType,
   int requestedUpdateRate,
   EasyDAItemChangedEventHandler^ callback,
   Object^ state
)

Parameters

machineName: Name of the machine. Determines the computer on which the OPC server is located. May be an empty string, in which case the OPC server is assumed to exist on the local computer or at the computer specified for it by DCOM configuration.
serverClass: Contains ProgID of the OPC server.
itemId: Contains OPC item identifier.
dataType: Specifies the data type requested. Passing OpcLabs.BaseLib.ComInterop.VarTypes.Empty means that the server's canonical data type should be used.
requestedUpdateRate: How often should the updates be received (number of milliseconds).
callback: A callback method to be invoked for each significant item change.
state: The state object (can be any value supplied by your code); available in event notifications.

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.ArgumentOutOfRangeException	The value of an argument is outside the allowable range of values as defined by the invoked method. 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.

System.ArgumentOutOfRangeException

The value of an argument is outside the allowable range of values as defined by the invoked method.

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

If is a null reference, only the notification events are generated, but no callback method is invoked.

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

EasyDAItemSubscriptionArguments Class
EasyDAItemSubscriptionArguments Members
Overload List

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