OPC Studio User's Guide and Reference
Examples - Server OPC UA - Handle conversion errors on server level

.NET

// This example shows how to handle conversion errors on the server level.
// 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;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UAServerDocExamples._EasyUAServer
{
    class ConversionError
    {
        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();

            // Define a data variable of type Byte.
            UADataVariable dataVariable = UADataVariable.CreateIn(server.Objects, "MyDataVariable").ValueType<byte>();

            // Add a Read handler that returns random values between 0 and 511. Those greater than 255 will cause conversion
            // errors.
            var random = new Random();
            dataVariable.Read += (sender, args) => args.HandleAndReturn(random.Next(0, 512));

            // Hook events to the server.
            // Note that the conversion error event can also be handled on the data variable or folder level, if that's what
            // you requirements call for.
            server.ConversionError += ServerOnConversionError;

            // 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.");
        }

        // Event handler for the ConversionError event. It simply prints out the event.
        static private void ServerOnConversionError(object sender, UADataVariableConversionErrorEventArgs e)
        {
            Console.WriteLine();
            Console.WriteLine($"*** {e}");

            // Following are some useful properties in the event notification:
            //   e.DataVariable
            //   e.Action
            //   e.ServiceResult

            switch (e.Action)
            {
                case UADataVariableConversionAction.Read:
                    Console.WriteLine("The conversion error occurred during a Read operation.");
                    break;
                case UADataVariableConversionAction.Write:
                    Console.WriteLine("The conversion error occurred during a Write operation.");
                    break;
                case UADataVariableConversionAction.Update:
                    Console.WriteLine("The conversion error occurred during an Update operation.");
                    break;
            }

            Console.WriteLine($"It occured on the data variable: {e.DataVariable}.");
            Console.WriteLine($"The service result was: {e.ServiceResult.Message}");
        }
    }
}
' This example shows how to handle conversion errors on the server level.
' 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
Imports OpcLabs.EasyOpc.UA.OperationModel

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

            ' Define a data variable of type Byte.
            Dim dataVariable As UADataVariable = UADataVariable.CreateIn(server.Objects, "MyDataVariable").ValueType(Of Byte)()

            ' Add a Read handler that returns random values between 0 and 511. Those greater than 255 will cause conversion
            ' errors.
            Dim random = New Random()
            AddHandler dataVariable.Read, Sub(sender, args) args.HandleAndReturn(random.Next(0, 512))

            ' Hook events to the server.
            ' Note that the conversion error event can also be handled on the data variable or folder level, if that's what
            ' you requirements call for.
            AddHandler server.ConversionError, AddressOf ServerOnConversionError

            ' 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

        ' Event handler for the ConversionError event. It simply prints out the event.
        Private Shared Sub ServerOnConversionError(ByVal sender As Object, ByVal e As UADataVariableConversionErrorEventArgs)
            Console.WriteLine()
            Console.WriteLine($"*** {e}")

            ' Following are some useful properties in the event notification:
            '   e.DataVariable
            '   e.Action
            '   e.ServiceResult

            Select Case e.Action
                Case UADataVariableConversionAction.Read
                    Console.WriteLine("The conversion error occurred during a Read operation.")
                Case UADataVariableConversionAction.Write
                    Console.WriteLine("The conversion error occurred during a Write operation.")
                Case UADataVariableConversionAction.Update
                    Console.WriteLine("The conversion error occurred during an Update operation.")
            End Select

            Console.WriteLine($"It occured on the data variable: {e.DataVariable}.")
            Console.WriteLine($"The service result was: {e.ServiceResult.Message}")
        End Sub
    End Class
End Namespace
See Also

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