Examples - OPC Unified Architecture - Subscribe to all variables in an object

// This example shows how to subscribe to changes of all data variables under a specified object in OPC UA address space.

using System;
using System.Linq;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.AddressSpace;
using OpcLabs.EasyOpc.UA.OperationModel;

namespace UADocExamples._EasyUAClient
{
    partial class SubscribeMultipleMonitoredItems
    {
        public static void AllInObject()
        {
            UAEndpointDescriptor endpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer";
            // or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            // or "https://opcua.demo-this.com:51212/UA/SampleServer/"
            
            // Instantiate the client object and hook events
            var client = new EasyUAClient();
            client.DataChangeNotification += client_DataChangeNotification_AllInObject;

            // Obtain variables under "Scalar" node
            Console.WriteLine("Browsing...");
            UANodeElementCollection nodeElementCollection;
            try
            {
                nodeElementCollection = client.BrowseDataVariables(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;ns=2;i=10787");
            }
            catch (UAException uaException)
            {
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException().Message);
                return;
            }

            // Create array with monitored item arguments
            EasyUAMonitoredItemArguments[] monitoredItemArgumentsArray = nodeElementCollection
                .Select(element => new EasyUAMonitoredItemArguments(null, endpointDescriptor, element))
                .ToArray();

            Console.WriteLine("Subscribing...");
            client.SubscribeMultipleMonitoredItems(monitoredItemArgumentsArray);

            Console.WriteLine("Processing monitored item changed events for 20 seconds...");
            System.Threading.Thread.Sleep(20 * 1000);

            Console.WriteLine("Unsubscribing...");
            client.UnsubscribeAllMonitoredItems();

            Console.WriteLine("Waiting for 5 seconds...");
            System.Threading.Thread.Sleep(5 * 1000);
        }

        static void client_DataChangeNotification_AllInObject(object sender, EasyUADataChangeNotificationEventArgs e)
        {
            // Display value
            if (e.Succeeded)
                Console.WriteLine("{0}: {1}", e.Arguments.NodeDescriptor, e.AttributeData.Value);
            else
                Console.WriteLine("{0} *** Failure: {1}", e.Arguments.NodeDescriptor, e.ErrorMessageBrief);
        }
    }
}

# This example shows how to subscribe to changes of multiple monitored items and display the value of the monitored item
# with each change.

# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import time

# Import .NET namespaces.
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.OperationModel import *


def dataChangeNotification(sender, e):
    # Display value.
    if e.Succeeded:
        print(e.Arguments.NodeDescriptor, ': ', e.AttributeData.Value, sep='')
    else:
        print(e.Arguments.NodeDescriptor, ' *** Failure: ', e.ErrorMessageBrief, sep='')


endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer')
# or 'http://opcua.demo-this.com:51211/UA/SampleServer' (currently not supported)
# or 'https://opcua.demo-this.com:51212/UA/SampleServer/'

# Instantiate the client object and hook events.
client = EasyUAClient()
client.DataChangeNotification += dataChangeNotification

# Obtain variables under "Scalar" node.
print('Browsing...')
try:
    nodeElementCollection = IEasyUAClientExtension.BrowseDataVariables(client,
        endpointDescriptor, UANodeDescriptor('nsu=http://test.org/UA/Data/ ;ns=2;i=10787'))
except UAException as uaException:
    print('*** Failure: ' + uaException.GetBaseException().Message)
    exit()

# Create array with monitored item arguments.
monitoredItemArgumentsArray = list(map(
    lambda element: EasyUAMonitoredItemArguments(None, endpointDescriptor, element.ToUANodeDescriptor()),
    nodeElementCollection))

print('Subscribing...')
client.SubscribeMultipleMonitoredItems(monitoredItemArgumentsArray)

print('Processing data change events for 20 seconds...')
time.sleep(20)

print('Unsubscribing...')
client.UnsubscribeAllMonitoredItems()

print('Waiting for 5 seconds...')
time.sleep(5)

print('Finished.')

' This example shows how to subscribe to changes of all data variables under a specified object in OPC UA address space.

Imports System.Linq
Imports OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.AddressSpace
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Partial Friend Class SubscribeMultipleMonitoredItems
        Public Shared Sub AllInObject()

            ' Define which server we will work with.
            Dim endpointDescriptor As UAEndpointDescriptor =
                "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
            ' or "http://opcua.demo-this.com:51211/UA/SampleServer" (currently not supported)
            ' or "https://opcua.demo-this.com:51212/UA/SampleServer/"

            ' Instantiate the client object and hook events
            Dim client = New EasyUAClient()
            AddHandler client.DataChangeNotification, AddressOf client_DataChangeNotification_AllInObject

            ' Obtain variables under "Scalar" node
            Console.WriteLine("Subscribing...")
            Dim nodeElementCollection As UANodeElementCollection
            Try
                nodeElementCollection = client.BrowseDataVariables(endpointDescriptor, "nsu=http://test.org/UA/Data/ ;ns=2;i=10787")
            Catch uaException As UAException
                Console.WriteLine("*** Failure: {0}", uaException.GetBaseException.Message)
                Exit Sub
            End Try

            ' Create array with monitored item arguments

            Dim monitoredItemArgumentsArray() As EasyUAMonitoredItemArguments = nodeElementCollection.Select(Function(element) New EasyUAMonitoredItemArguments(Nothing, endpointDescriptor, element)).ToArray()

            Console.WriteLine("Subscribing...")
            client.SubscribeMultipleMonitoredItems(monitoredItemArgumentsArray)

            Console.WriteLine("Processing monitored item changed events for 20 seconds...")
            Threading.Thread.Sleep(20 * 1000)

            Console.WriteLine("Unsubscribing...")
            client.UnsubscribeAllMonitoredItems()

            Console.WriteLine("Waiting for 5 seconds...")
            Threading.Thread.Sleep(5 * 1000)
        End Sub

        Private Shared Sub client_DataChangeNotification_AllInObject(ByVal sender As Object, ByVal e As EasyUADataChangeNotificationEventArgs)
            ' Display value
            If e.Succeeded Then
                Console.WriteLine("{0}: {1}", e.Arguments.NodeDescriptor, e.AttributeData.Value)
            Else
                Console.WriteLine("{0} *** Failure: {1}", e.Arguments.NodeDescriptor, e.ErrorMessageBrief)
            End If
        End Sub
    End Class
End Namespace

Conceptual

Subscribing to OPC UA Data Changes