// This example shows how to use a function to define what happens with the value 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
{
class WriteValueFunction
{
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 non-negative values to be written to the variable.
server.Add(new UADataVariable("WriteToThisVariable").WriteValueFunction<int>(
value =>
{
if (value < 0)
{
Console.WriteLine($"Value rejected: {value}");
return UACodeBits.BadOutOfRange;
}
Console.WriteLine($"Value written: {value}");
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.");
}
}
}