OPC Studio User's Guide and Reference
ConversionError Event (UAServerNode)
Example 



OpcLabs.ServerOpcUA Assembly > OpcLabs.EasyOpc.UA.NodeSpace Namespace > UAServerNode Class : ConversionError Event
Raised when data cannot be converted from Read, for Write, or in data subscription's OpcLabs.BaseLib.ISink<T>.OnNext.
Syntax
'Declaration
 
Public Event ConversionError As UADataVariableConversionErrorEventHandler
'Usage
 
Dim instance As UAServerNode
Dim handler As UADataVariableConversionErrorEventHandler
 
AddHandler instance.ConversionError, handler
public event UADataVariableConversionErrorEventHandler ConversionError
public:
event UADataVariableConversionErrorEventHandler^ ConversionError
Event Data

The event handler receives an argument of type UADataVariableConversionErrorEventArgs containing data related to this event. The following UADataVariableConversionErrorEventArgs properties provide information specific to this event.

PropertyDescription
Describes where the conversion error has occurred.  
The data variable being processed. (Inherited from OpcLabs.EasyOpc.UA.OperationModel.UADataVariableProcessedEventArgs)
(Inherited from System.ComponentModel.HandledEventArgs)
Contains the OPC UA service result of the failed conversion.  
Remarks

This event is raised in scenarios where data conversion fails during operations like reading from, writing to, or updating subscriptions in the OPC UA server. Handling this event allows for custom error handling or logging of conversion issues, which can be critical for diagnosing data integrity or compatibility problems.

Example
// 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}");
        }
    }
}
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