ReadWrite<TValue>(UADataVariable,UAAttributeData<TValue>) Method

Makes the data variable into a read-write register, specifying initial typed attribute data (typed value, status code, timestamp).

Syntax

Visual Basic
C#
C++/CLI

'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function ReadWrite(Of TValue)( _
   ByVal dataVariable As UADataVariable, _
   ByVal attributeData As UAAttributeData(Of TValue) _
) As UADataVariable

'Usage
 
Dim dataVariable As UADataVariable
Dim attributeData As UAAttributeData(Of TValue)
Dim value As UADataVariable
 
value = UADataVariableExtension.ReadWrite(Of TValue)(dataVariable, attributeData)

[Extension()]
[NotNull()]
public static UADataVariable ReadWrite<TValue>( 
   UADataVariable dataVariable,
   UAAttributeData<TValue> attributeData
)

[Extension()]
[NotNull()]
public:
static UADataVariable^ ReadWritegeneric<typename TValue>
( 
   UADataVariable^ dataVariable,
   UAAttributeData<TValue^>^ attributeData
)

Parameters

dataVariable: The data variable that will be modified and returned.
The value of this parameter cannot be null (Nothing in Visual Basic).
attributeData: The initial attribute data of the data variable.
The value of this parameter cannot be null (Nothing in Visual Basic).

Type Parameters

TValue: The type of the value of the data variable.

Return Value

Returns the , internally modified as defined by the method.

This method never returns 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

This method overload infers the OPC data type and value rank of the data variable from the TValue type.

This is an extension method (info: C#, VB.NET). In languages that have support for extensions methods (such as C# and VB.NET), you can use the extension method as if it were a regular method on the object that is its first parameter. In other languages (such as with Python.NET), you will call the extension as a static method, and pass it the object on which it acts as its first parameter.

Example

CSharp
VB.NET

// This example shows how to create a read-write data variable that behaves like a register, specifying initial attribute
// data (including the status code and source timestamp).
// 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.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.Generic;
using OpcLabs.EasyOpc.UA.NodeSpace;

namespace UAServerDocExamples._UADataVariable
{
    partial class ReadWrite
    {
        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 data variable that is a read-write register, defining its initial attribute data.
            // The type of the data variable (Int32, in this case) is inferred from the initial data.
            server.Add(new UADataVariable("MyVariable").ReadWrite(new UAAttributeData<int>(
                value:42,
                UACodeBits.GoodLocalOverride,
                DateTime.UtcNow)));

            // 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.");
        }
    }
}

' This example shows how to create a read-write data variable that behaves like a register, specifying initial attribute
' data (including the status code and source timestamp).
' 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.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.Generic
Imports OpcLabs.EasyOpc.UA.NodeSpace

Namespace _UADataVariable
    Partial Friend Class ReadWrite
        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 data variable that is a read-write register, defining its initial attribute data.
            ' The type of the data variable (Int32, in this case) is inferred from the initial data.
            server.Add(New UADataVariable("MyVariable").ReadWrite(New UAAttributeData(Of Integer)(
                value:=42,
                UACodeBits.GoodLocalOverride,
                DateTime.UtcNow)))

            ' 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
    End Class
End Namespace

CSharp
VB.NET

// This example shows how to create a read-write data variable that behaves like a register, specifying initial "Bad"
// attribute data.
// 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.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.Generic;
using OpcLabs.EasyOpc.UA.NodeSpace;

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

            // Create a data variable that is a read-write register, defining its initial attribute data.
            // The type of the data variable (Int32, in this case) is inferred from the initial data.
            server.Add(new UADataVariable("MyVariable").ReadWrite(new UAAttributeData<int>(
                value:0,
                UACodeBits.BadNoCommunication,
                DateTime.UtcNow)));

            // 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.");
        }
    }
}

' This example shows how to create a read-write data variable that behaves like a register, specifying initial "Bad"
' attribute data.
' 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.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.Generic
Imports OpcLabs.EasyOpc.UA.NodeSpace

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

            ' Create a data variable that is a read-write register, defining its initial attribute data.
            ' The type of the data variable (Int32, in this case) is inferred from the initial data.
            server.Add(New UADataVariable("MyVariable").ReadWrite(New UAAttributeData(Of Integer)(
                value:=0,
                UACodeBits.BadNoCommunication,
                DateTime.UtcNow)))

            ' 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
    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

UADataVariableExtension Class
UADataVariableExtension Members
Overload List

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