'Usage
Dim instance As UADataVariable Dim readValue As Object instance.UpdateReadAttributeData(readValue)
Parameters
- readValue
- The new value of the data variable for OPC reads.
The value of this parameter can be
null
(Nothing
in Visual Basic).
The value of this parameter can be null
(Nothing
in Visual Basic).
'Usage
Dim instance As UADataVariable Dim readValue As Object instance.UpdateReadAttributeData(readValue)
The value of this parameter can be null
(Nothing
in Visual Basic).
This method is useful in the data provision push model, as it combines the construction of the OpcLabs.EasyOpc.UA.UAAttributeData with obtaining the source timestamp and setting the ReadAttributeData. The source timestamp is set to the current time, and the status code is set to "Good". If your server provides its own source timestamps, do not use this method, construct OpcLabs.EasyOpc.UA.UAAttributeData yourself and set it into ReadAttributeData directly.
This method or property does not throw any exceptions, aside from execution exceptions such as System.Threading.ThreadAbortException or System.OutOfMemoryException.
// This example shows how to update the read value in the push data provision model. In this model, your code pushes the // data into the server, and the server then makes the data available to OPC clients. // 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 System.Timers; using OpcLabs.EasyOpc.UA; using OpcLabs.EasyOpc.UA.NodeSpace; namespace UAServerDocExamples._UADataVariable { class UpdateReadAttributeData { 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 read-only data variable. var dataVariable = UADataVariable.CreateIn(server.Objects, "ReadThisVariable") .ValueType<int>() .Writable(false); // Create a timer for pushing the data for OPC reads. In a real server the activity may also come from other // sources. var timer = new Timer { Interval = 1000, AutoReset = true, }; // Set the read attribute data of the data variable to a random value whenever the timer interval elapses. var random = new Random(); timer.Elapsed += (sender, args) => dataVariable.UpdateReadAttributeData(random.Next()); timer.Start(); // 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(); // Stop the timer. timer.Stop(); Console.WriteLine("The server is stopped."); } } }
' This example shows how to update the read value in the push data provision model. In this model, your code pushes the ' data into the server, and the server then makes the data available to OPC clients. ' 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 System.Timers Imports OpcLabs.EasyOpc.UA Imports OpcLabs.EasyOpc.UA.NodeSpace Namespace _UADataVariable Partial Friend Class UpdateReadAttributeData 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 read-only data variable. Dim dataVariable = UADataVariable.CreateIn(server.Objects, "ReadThisVariable") _ .ValueType(Of Integer)() _ .Writable(False) ' Create a timer for pushing the data for OPC reads. In a real server the activity may also come from other ' sources. Dim timer = New Timer With { .Interval = 1000, .AutoReset = True } ' Set the read attribute data of the data variable to a random value whenever the timer interval elapses. Dim random = New Random() AddHandler timer.Elapsed, Sub(sender, args) dataVariable.UpdateReadAttributeData(random.Next()) timer.Start() ' 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