OPC Studio User's Guide and Reference
Obtaining Subscription Information (OPC Data)
Concepts > QuickOPC Concepts > QuickOPC Development Models > Imperative Programming Model > Imperative Programming Model for OPC Data (Classic and UA) > Subscribing to Information (OPC Data) > Obtaining Subscription Information (OPC Data)

If you need to obtain information about a subscription made or modified earlier, you have two methods available in QuickOPC-UA.

Calling GetMonitoredItemArguments method with a handle obtained when the subscription was made will return an EasyUAMonitoredItemArguments object with all current parameters.

.NET

// This example shows how to obtain parameters of certain monitored item subscription.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-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.OperationModel;

namespace UADocExamples._EasyUAClient
{
    class GetMonitoredItemArguments
    {
        public static void Main1()
        {
            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;

            Console.WriteLine("Subscribing...");
            int[] handleArray = client.SubscribeMultipleMonitoredItems(new[]
                {
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10845", 1000),
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10853", 1000),
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10855", 1000)
                });

            Console.WriteLine("Getting monitored item arguments...");
            EasyUAMonitoredItemArguments monitoredItemArguments =
                client.GetMonitoredItemArguments(handleArray[2]);
            Console.WriteLine($"NodeDescriptor: {monitoredItemArguments.NodeDescriptor}");
            Console.WriteLine($"SamplingInterval: {monitoredItemArguments.MonitoringParameters.SamplingInterval}");
            Console.WriteLine($"PublishingInterval: {monitoredItemArguments.SubscriptionParameters.PublishingInterval}");

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

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

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

            Console.WriteLine("Finished.");
        }

        static void client_DataChangeNotification(object sender, EasyUADataChangeNotificationEventArgs e)
        {
            // Your code would do the processing here.
        }


        // Example output:
        //
        //Subscribing...
        //Getting monitored item arguments...
        //NodeDescriptor: NodeId="nsu=http://test.org/UA/Data/ ;i=10855"
        //SamplingInterval: 1000
        //PublishingInterval: 0
        //Waiting for 5 seconds...
        //Unsubscribing...
        //Waiting for 5 seconds...
        //Finished.

    }
}

# This example shows how to obtain parameters of certain monitored item subscription.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in PowerShell on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PowerShell .
# 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.

#requires -Version 5.1
using namespace OpcLabs.EasyOpc.UA
using namespace OpcLabs.EasyOpc.UA.OperationModel

# The path below assumes that the current directory is [ProductDir]/Examples-NET/PowerShell/Windows .
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcUA.dll"
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcUAComponents.dll"

[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.
$client = New-Object EasyUAClient

# Data change notification handler
Register-ObjectEvent -InputObject $client -EventName DataChangeNotification -Action { 
    # Your code would do the processing here.
}

Write-Host "Subscribing..."
$handleArray = $client.SubscribeMultipleMonitoredItems(@(
    (New-Object UAMonitoredItemArguments(
        (New-Object UAAttributeArguments($endpointDescriptor, [UANodeDescriptor]"nsu=http://test.org/UA/Data/ ;i=10845")), 
        1000)),
    (New-Object UAMonitoredItemArguments(
        (New-Object UAAttributeArguments($endpointDescriptor, [UANodeDescriptor]"nsu=http://test.org/UA/Data/ ;i=10853")), 
        1000)),
    (New-Object UAMonitoredItemArguments(
        (New-Object UAAttributeArguments($endpointDescriptor, [UANodeDescriptor]"nsu=http://test.org/UA/Data/ ;i=10855")),
        1000))
    ))

Write-Host "Getting monitored item arguments..."
$monitoredItemArguments = $client.GetMonitoredItemArguments($handleArray[2])
Write-Host "NodeDescriptor: $($monitoredItemArguments.NodeDescriptor)"
Write-Host "SamplingInterval: $($monitoredItemArguments.MonitoringParameters.SamplingInterval)"
Write-Host "PublishingInterval: $($monitoredItemArguments.SubscriptionParameters.PublishingInterval)"

Write-Host "Waiting for 5 seconds..."
Start-Sleep -Seconds 5

Write-Host "Unsubscribing..."
$client.UnsubscribeAllMonitoredItems()

Write-Host "Waiting for 5 seconds..."
Start-Sleep -Seconds 5

Write-Host "Finished."


# Example output:
#
#Subscribing...
#Getting monitored item arguments...
#NodeDescriptor: NodeId="nsu=http://test.org/UA/Data/ ;i=10855"
#SamplingInterval: 1000
#PublishingInterval: 0
#Waiting for 5 seconds...
#Unsubscribing...
#Waiting for 5 seconds...
#Finished.


' This example shows how to obtain parameters of certain monitored item subscription.
'
' 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 OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Friend Class GetMonitoredItemArguments
        Public Shared Sub Main1()

            ' 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

            Console.WriteLine("Subscribing...")
            Dim handleArray() As Integer = client.SubscribeMultipleMonitoredItems(New EasyUAMonitoredItemArguments() _
               { _
                   New EasyUAMonitoredItemArguments(Nothing, endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845", 1000), _
                   New EasyUAMonitoredItemArguments(Nothing, endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853", 1000), _
                   New EasyUAMonitoredItemArguments(Nothing, endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855", 1000) _
               } _
            )

            Console.WriteLine("Getting monitored item arguments...")
            Dim monitoredItemArguments As EasyUAMonitoredItemArguments = client.GetMonitoredItemArguments(handleArray(2))
            Console.WriteLine("NodeDescriptor: {0}", monitoredItemArguments.NodeDescriptor)
            Console.WriteLine("SamplingInterval: {0}", monitoredItemArguments.MonitoringParameters.SamplingInterval)
            Console.WriteLine("PublishingInterval: {0}", monitoredItemArguments.SubscriptionParameters.PublishingInterval)

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

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

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

        Private Shared Sub client_DataChangeNotification(ByVal sender As Object, ByVal e As EasyUADataChangeNotificationEventArgs)
            ' Your code would do the processing here
        End Sub
    End Class
End Namespace

COM

// This example shows how to obtain parameters of certain monitored item subscription.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in Object Pascal (Delphi) on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-OP .
// 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.

type
  TClientEventHandlers115 = class
    procedure Client_DataChangeNotification(
      ASender: TObject;
      sender: OleVariant;
      const eventArgs: _EasyUADataChangeNotificationEventArgs);
  end;

procedure TClientEventHandlers115.Client_DataChangeNotification(
  ASender: TObject;
  sender: OleVariant;
  const eventArgs: _EasyUADataChangeNotificationEventArgs);
begin
  // Your code would do the processing here
end;

class procedure GetMonitoredItemArguments.Main;
var
  Arguments: OleVariant;
  Client: TEasyUAClient;
  ClientEventHandlers: TClientEventHandlers115;
  HandleArray: OleVariant;
  MonitoredItemArguments1, MonitoredItemArguments2, MonitoredItemArguments3:
    _EasyUAMonitoredItemArguments;
  MonitoredItemArguments: _EasyUAMonitoredItemArguments;
begin
  // Instantiate the client object and hook events
  Client := TEasyUAClient.Create(nil);
  ClientEventHandlers := TClientEventHandlers115.Create;
  Client.OnDataChangeNotification := ClientEventHandlers.Client_DataChangeNotification;

  WriteLn('Subscribing...');
  MonitoredItemArguments1 := CoEasyUAMonitoredItemArguments.Create;
  MonitoredItemArguments1.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  MonitoredItemArguments1.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10845';
  MonitoredItemArguments2 := CoEasyUAMonitoredItemArguments.Create;
  MonitoredItemArguments2.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  MonitoredItemArguments2.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10853';
  MonitoredItemArguments3 := CoEasyUAMonitoredItemArguments.Create;
  MonitoredItemArguments3.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  MonitoredItemArguments3.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10855';

  Arguments := VarArrayCreate([0, 2], varVariant);
  Arguments[0] := MonitoredItemArguments1;
  Arguments[1] := MonitoredItemArguments2;
  Arguments[2] := MonitoredItemArguments3;

  TVarData(HandleArray).VType := varArray or varVariant;
  TVarData(HandleArray).VArray := PVarArray(
    Client.SubscribeMultipleMonitoredItems(Arguments));

  WriteLn('Getting monitored item arguments...');
  MonitoredItemArguments := Client.GetMonitoredItemArguments(HandleArray[2]);

  WriteLn('NodeDescriptor: ', MonitoredItemArguments.NodeDescriptor.ToString);
  WriteLn('SamplingInterval: ', MonitoredItemArguments.MonitoringParameters.ToString);
  WriteLn('PublishingInterval: ', MonitoredItemArguments.SubscriptionParameters.ToString);

  WriteLn('Waiting for 5 seconds...');
  PumpSleep(5*1000);

  WriteLn('Unsubscribing...');
  Client.UnsubscribeAllMonitoredItems;

  WriteLn('Waiting for 5 seconds...');
  Sleep(5*1000);

  WriteLn('Finished.');
  
  VarClear(HandleArray);
  VarClear(Arguments);
  FreeAndNil(Client);
  FreeAndNil(ClientEventHandlers);
end;

Rem This example shows how to obtain parameters of certain monitored item subscription.
Rem
Rem Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
Rem OPC client and subscriber examples in VBScript on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBScript .
Rem Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
Rem a commercial license in order to use Online Forums, and we reply to every post.

Option Explicit

' Instantiate the client object and hook events
Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient")
WScript.ConnectObject Client, "Client_"

WScript.Echo "Subscribing..."

Dim MonitoredItemArguments1: Set MonitoredItemArguments1 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.EasyUAMonitoredItemArguments")
MonitoredItemArguments1.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
MonitoredItemArguments1.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10845"

Dim MonitoredItemArguments2: Set MonitoredItemArguments2 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.EasyUAMonitoredItemArguments")
MonitoredItemArguments2.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
MonitoredItemArguments2.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10853"

Dim MonitoredItemArguments3: Set MonitoredItemArguments3 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.EasyUAMonitoredItemArguments")
MonitoredItemArguments3.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
MonitoredItemArguments3.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10855"

Dim arguments(2)
Set arguments(0) = MonitoredItemArguments1
Set arguments(1) = MonitoredItemArguments2
Set arguments(2) = MonitoredItemArguments3

Dim handleArray: handleArray = Client.SubscribeMultipleMonitoredItems(arguments)

WScript.Echo "Getting monitored item arguments..."
Dim MonitoredItemArguments: Set MonitoredItemArguments = Client.GetMonitoredItemArguments(handleArray(2))

WScript.Echo "NodeDescriptor: " & MonitoredItemArguments.NodeDescriptor
WScript.Echo "SamplingInterval: " & MonitoredItemArguments.MonitoringParameters.SamplingInterval
WScript.Echo "PublishingInterval: " & MonitoredItemArguments.SubscriptionParameters.PublishingInterval

WScript.Echo "Waiting for 5 seconds..."
WScript.Sleep 5 * 1000

WScript.Echo "Unsubscribing..."
Client.UnsubscribeAllMonitoredItems

WScript.Echo "Waiting for 5 seconds..."
WScript.Sleep 5 * 1000



Sub Client_DataChangeNotification(Sender, e)
    ' Your code would do the processing here
End Sub

Python

# This example shows how to obtain parameters of certain monitored item subscription.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# 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.
# 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):
    # Your code would do the processing here.
    pass


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

print('Subscribing...')
handleArray = client.SubscribeMultipleMonitoredItems([
    EasyUAMonitoredItemArguments(
        None,
        UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer'),
        UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10845'),
        UAMonitoringParameters(1000)),
    EasyUAMonitoredItemArguments(
        None,
        UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer'),
        UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10853'),
        UAMonitoringParameters(1000)),
    EasyUAMonitoredItemArguments(
        None,
        UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer'),
        UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10855'),
        UAMonitoringParameters(1000)),
    ])

print('Getting monitored item arguments...')
monitoredItemArguments = client.GetMonitoredItemArguments(handleArray[2])
print('NodeDescriptor: ', monitoredItemArguments.NodeDescriptor, sep='')
print('SamplingInterval: ', monitoredItemArguments.MonitoringParameters.SamplingInterval, sep='')
print('PublishingInterval: ', monitoredItemArguments.SubscriptionParameters.PublishingInterval, sep='')

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

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

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

print('Finished.')

 

Calling GetMonitoredItemArgumentsDictionary obtains information about all monitored item subscriptions on the EasyUAClient object. It returns a dictionary of monitored item argument objects (as above). The dictionary is keyed by the monitored item subscription handles, and its values contain information describing each subscription.

.NET

// This example shows how to obtain dictionary of parameters of all monitored item subscriptions.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in C# on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-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.OperationModel;

namespace UADocExamples._EasyUAClient
{
    class GetMonitoredItemArgumentsDictionary
    {
        public static void Main1()
        {
            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;

            Console.WriteLine("Subscribing...");
            client.SubscribeMultipleMonitoredItems(new[]
                {
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10845", 1000),
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10853", 1000),
                    new EasyUAMonitoredItemArguments(null, endpointDescriptor, 
                        "nsu=http://test.org/UA/Data/ ;i=10855", 1000)
                });

            Console.WriteLine("Getting monitored item arguments dictionary...");
            EasyUAMonitoredItemArgumentsDictionary monitoredItemArgumentsDictionary =
                client.GetMonitoredItemArgumentsDictionary();

            foreach (EasyUAMonitoredItemArguments monitoredItemArguments in monitoredItemArgumentsDictionary.Values)
            {
                Console.WriteLine();
                Console.WriteLine($"NodeDescriptor: {monitoredItemArguments.NodeDescriptor}");
                Console.WriteLine($"SamplingInterval: {monitoredItemArguments.MonitoringParameters.SamplingInterval}");
                Console.WriteLine($"PublishingInterval: {monitoredItemArguments.SubscriptionParameters.PublishingInterval}");
            }

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

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

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

            Console.WriteLine("Finished.");
        }

        static void client_DataChangeNotification(object sender, EasyUADataChangeNotificationEventArgs e)
        {
            // Your code would do the processing here.
        }


        // Example output:
        //
        //Subscribing...
        //Getting monitored item arguments dictionary...
        //
        //NodeDescriptor: NodeId="nsu=http://test.org/UA/Data/ ;i=10845"
        //SamplingInterval: 1000
        //PublishingInterval: 0
        //
        //NodeDescriptor: NodeId="nsu=http://test.org/UA/Data/ ;i=10853"
        //SamplingInterval: 1000
        //PublishingInterval: 0
        //
        //NodeDescriptor: NodeId="nsu=http://test.org/UA/Data/ ;i=10855"
        //SamplingInterval: 1000
        //PublishingInterval: 0
        //
        //Waiting for 5 seconds...
        //Unsubscribing...
        //Waiting for 5 seconds...
        //Finished.
    }
}

# This example shows how to obtain dictionary of parameters of all monitored item subscriptions.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in PowerShell on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-PowerShell .
# 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.

#requires -Version 5.1
using namespace OpcLabs.EasyOpc.UA
using namespace OpcLabs.EasyOpc.UA.OperationModel

# The path below assumes that the current directory is [ProductDir]/Examples-NET/PowerShell/Windows .
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcUA.dll"
Add-Type -Path "../../../Components/Opclabs.QuickOpc/net472/OpcLabs.EasyOpcUAComponents.dll"

[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.
$client = New-Object EasyUAClient

# Data change notification handler
Register-ObjectEvent -InputObject $client -EventName DataChangeNotification -Action { 
    # Your code would do the processing here.
}

Write-Host "Subscribing..."
$handleArray = $client.SubscribeMultipleMonitoredItems(@(
    (New-Object UAMonitoredItemArguments(
        (New-Object UAAttributeArguments($endpointDescriptor, [UANodeDescriptor]"nsu=http://test.org/UA/Data/ ;i=10845")), 
        1000)),
    (New-Object UAMonitoredItemArguments(
        (New-Object UAAttributeArguments($endpointDescriptor, [UANodeDescriptor]"nsu=http://test.org/UA/Data/ ;i=10853")), 
        1000)),
    (New-Object UAMonitoredItemArguments(
        (New-Object UAAttributeArguments($endpointDescriptor, [UANodeDescriptor]"nsu=http://test.org/UA/Data/ ;i=10855")),
        1000))
    ))

Write-Host "Getting monitored item arguments dictionary..."
$monitoredItemArgumentsDictionary = $client.GetMonitoredItemArgumentsDictionary()

foreach ($monitoredItemArguments in $monitoredItemArgumentsDictionary.Values) {
    Write-Host
    Write-Host "NodeDescriptor: $($monitoredItemArguments.NodeDescriptor)"
    Write-Host "SamplingInterval: $($monitoredItemArguments.MonitoringParameters.SamplingInterval)"
    Write-Host "PublishingInterval: $($monitoredItemArguments.SubscriptionParameters.PublishingInterval)"
}

Write-Host
Write-Host "Waiting for 5 seconds..."
Start-Sleep -Seconds 5

Write-Host "Unsubscribing..."
$client.UnsubscribeAllMonitoredItems()

Write-Host "Waiting for 5 seconds..."
Start-Sleep -Seconds 5

Write-Host "Finished."


# Example output:
#
#Subscribing...
#Getting monitored item arguments dictionary...
#
#NodeDescriptor: NodeId="nsu=http://test.org/UA/Data/ ;i=10845"
#SamplingInterval: 1000
#PublishingInterval: 0
#
#NodeDescriptor: NodeId="nsu=http://test.org/UA/Data/ ;i=10853"
#SamplingInterval: 1000
#PublishingInterval: 0
#
#NodeDescriptor: NodeId="nsu=http://test.org/UA/Data/ ;i=10855"
#SamplingInterval: 1000
#PublishingInterval: 0
#
#Waiting for 5 seconds...
#Unsubscribing...
#Waiting for 5 seconds...
#Finished.


' This example shows how to obtain dictionary of parameters of all monitored item subscriptions.
'
' 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 OpcLabs.EasyOpc.UA
Imports OpcLabs.EasyOpc.UA.OperationModel

Namespace _EasyUAClient
    Friend Class GetMonitoredItemArgumentsDictionary
        Public Shared Sub Main1()

            ' 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

            Console.WriteLine("Subscribing...")
            client.SubscribeMultipleMonitoredItems(New EasyUAMonitoredItemArguments() _
                { _
                    New EasyUAMonitoredItemArguments(Nothing, endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10845", 1000), _
                    New EasyUAMonitoredItemArguments(Nothing, endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10853", 1000), _
                    New EasyUAMonitoredItemArguments(Nothing, endpointDescriptor, "nsu=http://test.org/UA/Data/ ;i=10855", 1000) _
                } _
             )

            Console.WriteLine("Getting monitored item arguments dictionary...")
            Dim monitoredItemArgumentsDictionary As EasyUAMonitoredItemArgumentsDictionary = _
                    client.GetMonitoredItemArgumentsDictionary()

            For Each monitoredItemArguments As EasyUAMonitoredItemArguments In monitoredItemArgumentsDictionary.Values
                Console.WriteLine()
                Console.WriteLine("NodeDescriptor: {0}", monitoredItemArguments.NodeDescriptor)
                Console.WriteLine("SamplingInterval: {0}", monitoredItemArguments.MonitoringParameters.SamplingInterval)
                Console.WriteLine("PublishingInterval: {0}", monitoredItemArguments.SubscriptionParameters.PublishingInterval)
            Next monitoredItemArguments

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

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

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

        Private Shared Sub client_DataChangeNotification(ByVal sender As Object, ByVal e As EasyUADataChangeNotificationEventArgs)
            ' Your code would do the processing here
        End Sub
    End Class
End Namespace

COM

// This example shows how to obtain dictionary of parameters of all monitored item subscriptions.
//
// Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
// OPC client and subscriber examples in Object Pascal (Delphi) on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-OP .
// 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.

type
  TClientEventHandlers116 = class
    procedure Client_DataChangeNotification(
      ASender: TObject;
      sender: OleVariant;
      const eventArgs: _EasyUADataChangeNotificationEventArgs);
  end;

procedure TClientEventHandlers116.Client_DataChangeNotification(
  ASender: TObject;
  sender: OleVariant;
  const eventArgs: _EasyUADataChangeNotificationEventArgs);
begin
  // Your code would do the processing here
end;

class procedure GetMonitoredItemArgumentsDictionary.Main;
var
  Arguments: OleVariant;
  Client: TEasyUAClient;
  ClientEventHandlers: TClientEventHandlers116;
  Count: Cardinal;
  Element: OleVariant;
  HandleArray: OleVariant;
  MonitoredItemArguments1, MonitoredItemArguments2, MonitoredItemArguments3:
    _EasyUAMonitoredItemArguments;
  MonitoredItemArguments: _EasyUAMonitoredItemArguments;
  MonitoredItemArgumentsDictionary: _EasyUAMonitoredItemArgumentsDictionary;
  MonitoredItemArgumentsEnumerator: IEnumVARIANT;
begin
  // Instantiate the client object and hook events
  Client := TEasyUAClient.Create(nil);
  ClientEventHandlers := TClientEventHandlers116.Create;
  Client.OnDataChangeNotification := ClientEventHandlers.Client_DataChangeNotification;

  WriteLn('Subscribing...');
  MonitoredItemArguments1 := CoEasyUAMonitoredItemArguments.Create;
  MonitoredItemArguments1.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  MonitoredItemArguments1.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10845';
  MonitoredItemArguments2 := CoEasyUAMonitoredItemArguments.Create;
  MonitoredItemArguments2.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  MonitoredItemArguments2.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10853';
  MonitoredItemArguments3 := CoEasyUAMonitoredItemArguments.Create;
  MonitoredItemArguments3.EndpointDescriptor.UrlString := 
    //'http://opcua.demo-this.com:51211/UA/SampleServer';
    //'https://opcua.demo-this.com:51212/UA/SampleServer/';
    'opc.tcp://opcua.demo-this.com:51210/UA/SampleServer';
  MonitoredItemArguments3.NodeDescriptor.NodeId.ExpandedText := 'nsu=http://test.org/UA/Data/ ;i=10855';

  Arguments := VarArrayCreate([0, 2], varVariant);
  Arguments[0] := MonitoredItemArguments1;
  Arguments[1] := MonitoredItemArguments2;
  Arguments[2] := MonitoredItemArguments3;

  TVarData(HandleArray).VType := varArray or varVariant;
  TVarData(HandleArray).VArray := PVarArray(
    Client.SubscribeMultipleMonitoredItems(Arguments));

  WriteLn('Getting monitored item arguments dictionary...');
  MonitoredItemArgumentsDictionary := Client.GetMonitoredItemArgumentsDictionary;

  MonitoredItemArgumentsEnumerator := MonitoredItemArgumentsDictionary.GetEnumerator;
  while (MonitoredItemArgumentsEnumerator.Next(1, Element, Count) = S_OK) do
  begin
    MonitoredItemArguments := IUnknown(Element.Value) as _EasyUAMonitoredItemArguments;
    WriteLn;
    WriteLn('NodeDescriptor: ', MonitoredItemArguments.NodeDescriptor.ToString);
    WriteLn('SamplingInterval: ', MonitoredItemArguments.MonitoringParameters.ToString);
    WriteLn('PublishingInterval: ', MonitoredItemArguments.SubscriptionParameters.ToString);
  end;

  WriteLn('Waiting for 5 seconds...');
  PumpSleep(5*1000);

  WriteLn('Unsubscribing...');
  Client.UnsubscribeAllMonitoredItems;

  WriteLn('Waiting for 5 seconds...');
  Sleep(5*1000);

  WriteLn('Finished.');
  VarClear(HandleArray);
  VarClear(Arguments);
  FreeAndNil(Client);
  FreeAndNil(ClientEventHandlers);
end;

Rem This example shows how to obtain dictionary of parameters of all monitored item subscriptions.
Rem
Rem Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
Rem OPC client and subscriber examples in VBScript on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-VBScript .
Rem Missing some example? Ask us for it on our Online Forums, https://www.opclabs.com/forum/index ! You do not have to own
Rem a commercial license in order to use Online Forums, and we reply to every post.

Option Explicit

' Instantiate the client object and hook events
Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.UA.EasyUAClient")
WScript.ConnectObject Client, "Client_"

WScript.Echo "Subscribing..."

Dim MonitoredItemArguments1: Set MonitoredItemArguments1 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.EasyUAMonitoredItemArguments")
MonitoredItemArguments1.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
MonitoredItemArguments1.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10845"

Dim MonitoredItemArguments2: Set MonitoredItemArguments2 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.EasyUAMonitoredItemArguments")
MonitoredItemArguments2.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
MonitoredItemArguments2.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10853"

Dim MonitoredItemArguments3: Set MonitoredItemArguments3 = CreateObject("OpcLabs.EasyOpc.UA.OperationModel.EasyUAMonitoredItemArguments")
MonitoredItemArguments3.EndpointDescriptor.UrlString = "opc.tcp://opcua.demo-this.com:51210/UA/SampleServer"
MonitoredItemArguments3.NodeDescriptor.NodeId.ExpandedText = "nsu=http://test.org/UA/Data/ ;i=10855"

Dim arguments(2)
Set arguments(0) = MonitoredItemArguments1
Set arguments(1) = MonitoredItemArguments2
Set arguments(2) = MonitoredItemArguments3

Dim handleArray: handleArray = Client.SubscribeMultipleMonitoredItems(arguments)

WScript.Echo "Getting monitored item arguments dictionary..."   
Dim MonitoredItemArgumentsDictionary: Set MonitoredItemArgumentsDictionary = Client.GetMonitoredItemArgumentsDictionary

Dim DictionaryEntry: For Each DictionaryEntry In MonitoredItemArgumentsDictionary
    Dim MonitoredItemArguments: Set MonitoredItemArguments = DictionaryEntry.Value
    WScript.Echo 
    WScript.Echo "NodeDescriptor: " & MonitoredItemArguments.NodeDescriptor
    WScript.Echo "SamplingInterval: " & MonitoredItemArguments.MonitoringParameters.SamplingInterval
    WScript.Echo "PublishingInterval: " & MonitoredItemArguments.SubscriptionParameters.PublishingInterval
Next

WScript.Echo "Waiting for 5 seconds..."
WScript.Sleep 5 * 1000

WScript.Echo "Unsubscribing..."
Client.UnsubscribeAllMonitoredItems

WScript.Echo "Waiting for 5 seconds..."
WScript.Sleep 5 * 1000



Sub Client_DataChangeNotification(Sender, e)
    ' Your code would do the processing here
End Sub

Python

# This example shows how to obtain dictionary of parameters of all monitored item subscriptions.
#
# Find all latest examples here: https://opclabs.doc-that.com/files/onlinedocs/OPCLabs-OpcStudio/Latest/examples.html .
# OPC client and subscriber examples in Python on GitHub: https://github.com/OPCLabs/Examples-QuickOPC-Python .
# 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.
# 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):
    # Your code would do the processing here.
    pass


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

print('Subscribing...')
handleArray = client.SubscribeMultipleMonitoredItems([
    EasyUAMonitoredItemArguments(
        None,
        UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer'),
        UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10845'),
        UAMonitoringParameters(1000)),
    EasyUAMonitoredItemArguments(
        None,
        UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer'),
        UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10853'),
        UAMonitoringParameters(1000)),
    EasyUAMonitoredItemArguments(
        None,
        UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:51210/UA/SampleServer'),
        UANodeDescriptor('nsu=http://test.org/UA/Data/ ;i=10855'),
        UAMonitoringParameters(1000)),
    ])

print('Getting monitored item arguments dictionary...')
monitoredItemArgumentsDictionary = client.GetMonitoredItemArgumentsDictionary()

for monitoredItemArguments in monitoredItemArgumentsDictionary.Values:
    print()
    print('NodeDescriptor: ', monitoredItemArguments.NodeDescriptor, sep='')
    print('SamplingInterval: ', monitoredItemArguments.MonitoringParameters.SamplingInterval, sep='')
    print('PublishingInterval: ', monitoredItemArguments.SubscriptionParameters.PublishingInterval, sep='')

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

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

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

print('Finished.')

 

 

See Also
Unsubscribing (OPC Data)
Changing Existing Subscription (OPC Data)
Subscribing to OPC UA Data Changes
Subscribing to OPC Classic Items
OPC Classic Item Changed Event or Callback
OPC UA Monitored Item Changed Event or Callback
Using Callback Methods Instead of Event Handlers (OPC Data)
Subscribing to Information (OPC Data)
Imperative Programming Model for OPC Data (Classic and UA)
Imperative Programming Model

 

 

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