'Usage
Dim name As String Dim instance As New UADataVariable(name)
Parameters
- name
- The name of the data variable.
The value of this parameter cannot be
null
(Nothing
in Visual Basic).
The value of this parameter cannot be null
(Nothing
in Visual Basic).
'Usage
Dim name As String Dim instance As New UADataVariable(name)
The value of this parameter cannot be null
(Nothing
in Visual Basic).
Exception | Description |
---|---|
System.ArgumentNullException |
A 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. |
// This example shows how to create a data variable and implement reading its attribute data using a function. // 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 ReadFunction { 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, defining its read attribute data (including status code and source timestamp) by a // function. // The type of the data variable (Int32, in this case) is inferred from the type returned by the function. var random = new Random(); server.Add(new UADataVariable("ReadThisVariable").ReadFunction(() => new UAAttributeData<int>( random.Next(), DateTime.UtcNow.AddMinutes(-10)))); // 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 data variable and implement reading its attribute data using a function. ' 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 ReadFunction 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, defining its read attribute data (including status code and source timestamp) by a ' function. ' The type of the data variable (Int32, in this case) is inferred from the type returned by the function. Dim random = New Random() server.Add(New UADataVariable("ReadThisVariable").ReadFunction(Function() New UAAttributeData(Of Integer)( random.Next(), DateTime.UtcNow.AddMinutes(-10)))) ' 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