AttributeData Property (UADataVariableWriteEventArgs)

The value/timestamps/status code that is the input of the OPC UA write.

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<NotNullAttribute()>
Public Property AttributeData As UAAttributeData

'Usage
 
Dim instance As UADataVariableWriteEventArgs
Dim value As UAAttributeData
 
instance.AttributeData = value
 
value = instance.AttributeData

[NotNull()]
public UAAttributeData AttributeData {get; set;}

[NotNull()]
public:
property UAAttributeData^ AttributeData {
   UAAttributeData^ get();
   void set (    UAAttributeData^ value);
}

Property Value

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

Exceptions

Exception Description

Exception	Description
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.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 source timestamp is present iff the OpcLabs.EasyOpc.UA.NodeSpace.UADataVariable.WritableSourceTimestamp of the UADataVariableProcessedEventArgs.DataVariable is true.

The status code is present iff the OpcLabs.EasyOpc.UA.NodeSpace.UADataVariable.WritableStatusCode of the UADataVariableProcessedEventArgs.DataVariable is true.

Example

CSharp
VB.NET

// This example shows how to handle the write event on a folder, providing a way to implement writing of multiple data
// variables using a single handler.
// You can use any OPC UA client, including our Connectivity Explorer and OpcCmd utility, to connect to the server. 
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client, server and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-OPCStudio-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 OpcLabs.BaseLib.NodeSpace;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.NodeSpace;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UAServerDocExamples._UAServerNode
{
    class Write
    {
        public static void Main1()
        {
            // Instantiate the server object.
            // By default, the server will run on endpoint URL "opc.tcp://localhost:48040/".
            var server = new EasyUAServer();

            // Create a folder node.
            UAFolder myFolder = UAFolder.CreateIn(server.Objects, "MyFolder");

            // Create data variables in the folder. Distinguish them by their state.
            myFolder.Add(new UADataVariable("MyDataVariable1").ValueType<int>().SetState(1));
            myFolder.Add(new UADataVariable("MyDataVariable2").ValueType<int>().SetState(2));
            myFolder.Add(new UADataVariable("MyDataVariable3").ValueType<int>().SetState(3));
            myFolder.Add(new UADataVariable("MyDataVariable4").ValueType<int>().SetState(4));
            myFolder.Add(new UADataVariable("MyDataVariable5").ValueType<int>().SetState(5));

            // Handle the write event for the folder.
            myFolder.Write += MyFolderOnWrite;

            // Start the server.
            Console.WriteLine("The server is starting...");
            server.Start();

            Console.WriteLine("The server is started.");
            Console.WriteLine();

            // Let the user decide when to stop.
            Console.WriteLine("Press Enter to stop the server...");
            Console.ReadLine();

            // Stop the server.
            Console.WriteLine("The server is stopping...");
            server.Stop();

            Console.WriteLine("The server is stopped.");
        }

        /// <summary>
        /// Event handler for the write event on the folder. 
        /// </summary>
        /// <param name="sender">The folder object that sends the event.</param>
        /// <param name="e">Data for the variable write event.</param>
        static private void MyFolderOnWrite(object sender, UADataVariableWriteEventArgs e)
        {
            // Obtain the state associated with the data variable that is being written, and display it on the console
            // together with the new value.
            Console.WriteLine($"Data variable {e.DataVariable.State}, value written: {e.AttributeData.Value}");
        }
    }
}

' This example shows how to handle the write event on a folder, providing a way to implement writing of multiple data
' variables using a single handler.
' You can use any OPC UA client, including our Connectivity Explorer and OpcCmd utility, to connect to the 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 System
Imports OpcLabs.BaseLib.NodeSpace
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.NodeSpace
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _UAServerNode
    Partial Friend Class Write
        Shared Sub Main1()
            ' Instantiate the server object.
            ' By default, the server will run on endpoint URL "opc.tcp://localhost:48040/".
            Dim server = New EasyUAServer()

            ' Create a folder node.
            Dim myFolder As UAFolder = UAFolder.CreateIn(server.Objects, "MyFolder")

            ' Create data variables in the folder. Distinguish them by their state.
            myFolder.Add(New UADataVariable("MyDataVariable1").ValueType(Of Integer)().SetState(1))
            myFolder.Add(New UADataVariable("MyDataVariable2").ValueType(Of Integer)().SetState(2))
            myFolder.Add(New UADataVariable("MyDataVariable3").ValueType(Of Integer)().SetState(3))
            myFolder.Add(New UADataVariable("MyDataVariable4").ValueType(Of Integer)().SetState(4))
            myFolder.Add(New UADataVariable("MyDataVariable5").ValueType(Of Integer)().SetState(5))

            ' Handle the read event for the folder.
            AddHandler myFolder.Write, AddressOf MyFolderOnWrite

            ' Start the server.
            Console.WriteLine("The server is starting...")
            server.Start()

            Console.WriteLine("The server is started.")
            Console.WriteLine()

            ' Let the user decide when to stop.
            Console.WriteLine("Press Enter to stop the server...")
            Console.ReadLine()

            ' Stop the server.
            Console.WriteLine("The server is stopping...")
            server.Stop()

            Console.WriteLine("The server is stopped.")
        End Sub

        ''' <summary>
        ''' Event handler for the write event on the folder.  
        ''' </summary>
        ''' <param name="sender">The data variable object that sends the event.</param>
        ''' <param name="e">Data for the variable write event.</param>
        Private Shared Sub MyFolderOnWrite(ByVal sender As Object, ByVal e As UADataVariableWriteEventArgs)
            ' Obtain the state associated with the data variable that is being written, and display it on the console
            ' together with the new value.
            Console.WriteLine($"Data variable {e.DataVariable.State}, value written: {e.AttributeData.Value}")
        End Sub

        Private Shared ReadOnly Random As Random = New Random()
    End Class
End Namespace

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

UADataVariableWriteEventArgs Class
UADataVariableWriteEventArgs Members

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