OPC Studio User's Guide and Reference
ReadWriteValue<TValue>(UADataVariable,TValue,Int32[]) Method
Example 



OpcLabs.ServerOpcUA Assembly > OpcLabs.EasyOpc.UA.NodeSpace Namespace > UADataVariableExtension Class > ReadWriteValue Method : ReadWriteValue<TValue>(UADataVariable,TValue,Int32[]) Method
The type of the value of the data variable.
The data variable that will be modified and returned.

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

The initial value of the data variable.

The value of this parameter can be null (Nothing in Visual Basic).

The size of each dimension of the array value.

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

Makes the data variable into a read-write register, specifying the typed initial value, and array dimensions.
Syntax
'Declaration
 
<ExtensionAttribute()>
<NotNullAttribute()>
Public Overloads Shared Function ReadWriteValue(Of TValue)( _
   ByVal dataVariable As UADataVariable, _
   ByVal value As TValue, _
   ByVal ParamArray arrayDimensions() As Integer _
) As UADataVariable
'Usage
 
Dim dataVariable As UADataVariable
Dim value As TValue
Dim arrayDimensions() As Integer
Dim value As UADataVariable
 
value = UADataVariableExtension.ReadWriteValue(Of TValue)(dataVariable, value, arrayDimensions)
[Extension()]
[NotNull()]
public static UADataVariable ReadWriteValue<TValue>( 
   UADataVariable dataVariable,
   TValue value,
   params int[] arrayDimensions
)
[Extension()]
[NotNull()]
public:
static UADataVariable^ ReadWriteValuegeneric<typename TValue>
( 
   UADataVariable^ dataVariable,
   TValue^ value,
   ... array<int>^ arrayDimensions
) 

Parameters

dataVariable
The data variable that will be modified and returned.

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

value
The initial value of the data variable.

The value of this parameter can be null (Nothing in Visual Basic).

arrayDimensions
The size of each dimension of the array value.

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 dataVariable, internally modified as defined by the method.

This method never returns null (Nothing in Visual Basic).

Exceptions
ExceptionDescription

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 of the data variable from the TValue type.

The array dimensions are specified as a list of integers, one for each dimension. Each element represents a dimension of the array, and the value of the element represents the maximum size of the array in that dimension. If the maximum size of certain dimension is unknown, the value of corresponding element is 0.

The specified array dimensions will be stored in the ArrayDimensions property, and exposed to OPC UA clients via the OpcLabs.EasyOpc.UA.UAAttributeId.ArrayDimensions attribute. In addition, OPC Wizard will enforce the maximum array bounds automatically (where the specified array dimension is not 0).

When you use the method overload without the array dimensions (arrayDimensions parameter), the method determines the array dimensions automatically from the TValue type parameter, and if the type is an array, the individual dimension elements are set to 0, meaning that the size of the array is not limited in any dimension. If you want to limit the size of the array in certain dimensions, you need to use this method overload (with arrayDimensions parameter), and specify the array dimensions explicitly.

In languages that support parameter arrays (methods with variable number of arguments), such as C# or VB.NET, the arrayDimensions parameter can be specified as one or more arguments of type System.Int32, without having to construct the array of dimensions explicitly.

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
// This example shows how to create a read-write data variable of an array type that behaves like a register, and enforces
// maximum array dimensions.
// 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.NodeSpace;

namespace UAServerDocExamples._UADataVariable
{
    partial class ReadWriteValue
    {
        public static void BoundedArray()
        {
            // 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 value, and maximum array size.
            // The type of the data variable (Int32 array, in this case) is inferred from the initial value.
            server.Add(new UADataVariable("MyVariable").ReadWriteValue(new int[4], arrayDimensions:5));

            // 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 of an array type that behaves like a register, and enforces
' maximum array dimensions.
' 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.NodeSpace

Namespace _UADataVariable
    Partial Friend Class ReadWriteValue
        Shared Sub BoundedArray()
            ' 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 value, and maximum array size.
            ' The type of the data variable (Int32 array, in this case) is inferred from the initial value.
            server.Add(New UADataVariable("MyVariable").ReadWriteValue(New Integer(3) {}, 5))

            ' 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

See Also