// This example shows how to use a function to define what happens with the attribute data when an OPC client writes to a // data variable. This is an example of the push data consumption model. // 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 WriteFunction { 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 writable data variable and add a function that will be called when the data variable is written to. // The function returns a status code that indicates the outcome of the Write operation. We have chosen to only // allow "Good" and "Uncertain", non-negative values to be written to the variable. server.Add(new UADataVariable("WriteToThisVariable").WriteFunction<int>( data => { if (data.StatusCode.IsBad || (data.TypedValue < 0)) { Console.WriteLine($"Attribute data rejected: {data}"); return UACodeBits.BadOutOfRange; } Console.WriteLine($"Attribute data written: {data}"); return null; // "Good" })); // Start the server. Console.WriteLine("The server is starting..."); server.Start(); Console.WriteLine("The server is started."); Console.WriteLine("Any value written to the example data variable will be displayed on the console."); 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 use a function to define what happens with the attribute data when an OPC client writes to a ' data variable. This is an example of the push data consumption model. ' 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 WriteFunction 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 writable data variable and add a function that will be called when the data variable is written to. ' The function returns a status code that indicates the outcome of the Write operation. We have chosen to only ' allow "Good" and "Uncertain", non-negative values to be written to the variable. server.Add(New UADataVariable("WriteToThisVariable").WriteFunction(Of Integer)( Function(data) If data.StatusCode.IsBad OrElse (data.TypedValue < 0) Then Console.WriteLine($"Attribute data rejected: {data}") Return UACodeBits.BadOutOfRange End If Console.WriteLine($"Attribute data written: {data}") Return Nothing ' "Good" End Function )) ' Start the server. Console.WriteLine("The server is starting...") server.Start() Console.WriteLine("The server is started.") Console.WriteLine("Any value written to the example data variable will be displayed on the console.") 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
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