OPC Studio User's Guide and Reference
Specifying event filters (OPC A&E)
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Concepts > QuickOPC Concepts > QuickOPC Development Models > Imperative Programming Model > Imperative Programming Model for OPC Classic A&E > Subscribing to Information (OPC A&E) > Specifying event filters (OPC A&E)

Examples:

Filtering by category or categories:

.NET

// This example shows how to filter the events by their category.
//
// 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 System.Threading;
using OpcLabs.EasyOpc.AlarmsAndEvents;
using OpcLabs.EasyOpc.AlarmsAndEvents.OperationModel;
using OpcLabs.EasyOpc.DataAccess;

namespace DocExamples.AlarmsAndEvents._EasyAEClient
{
    partial class SubscribeEvents
    {
        // Instantiate the OPC-A&E client object.
        static readonly EasyAEClient AEClient = new EasyAEClient();

        // Instantiate the OPC-DA client object.
        static readonly EasyDAClient DAClient = new EasyDAClient();

        public static void FilterByCategories()
        {
            var eventHandler = new EasyAENotificationEventHandler(AEClient_Notification_FilterByCategories);
            AEClient.Notification += eventHandler;

            Console.WriteLine("Processing event notifications...");
            var subscriptionFilter = new AESubscriptionFilter
            {
                Categories = new long[] { 15531778 }
            };
            // You can also filter using event types, severity, areas, and sources.
            int handle = AEClient.SubscribeEvents("", "OPCLabs.KitEventServer.2", 1000, null, subscriptionFilter);

            // Allow time for initial refresh
            Thread.Sleep(5 * 1000);

            // Set some events to active state.
            DAClient.WriteItemValue("", "OPCLabs.KitServer.2", "SimulateEvents.ConditionState1.Activate", true);
            DAClient.WriteItemValue("", "OPCLabs.KitServer.2", "SimulateEvents.ConditionState2.Activate", true);

            Thread.Sleep(10 * 1000);

            AEClient.UnsubscribeEvents(handle);
            AEClient.Notification -= eventHandler;
        }

        // Notification event handler
        static void AEClient_Notification_FilterByCategories(object sender, EasyAENotificationEventArgs e)
        {
            Console.WriteLine();
            Console.WriteLine(e);
            if (!e.Succeeded)
                return;

            Console.WriteLine("Refresh: {0}", e.Refresh);
            Console.WriteLine("RefreshComplete: {0}", e.RefreshComplete);
            AEEventData eventData = e.EventData;
            if (!(eventData is null))
            {
                Console.WriteLine("Event.CategoryId: {0}", eventData.CategoryId);
                Console.WriteLine("Event.QualifiedSourceName: {0}", eventData.QualifiedSourceName);
                Console.WriteLine("Event.Message: {0}", eventData.Message);
                Console.WriteLine("Event.Active: {0}", eventData.Active);
                Console.WriteLine("Event.Acknowledged: {0}", eventData.Acknowledged);
            }
        }
    }
}

Python

# This example shows how to filter the events by their category.
#
# 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 import *
from OpcLabs.EasyOpc.AlarmsAndEvents import *
from OpcLabs.EasyOpc.DataAccess import *
from OpcLabs.EasyOpc.OperationModel import *


# Notification event handler
def notification(sender, e):
    print()
    print(e)
    if not e.Succeeded:
        return
    print('Refresh: ', e.Refresh, sep='')
    print('RefreshComplete: ', e.RefreshComplete, sep='')
    eventData = e.EventData
    if eventData is not None:
        print('Event.CategoryId: ', eventData.CategoryId, sep='')
        print('Event.QualifiedSourceName: ', eventData.QualifiedSourceName, sep='')
        print('Event.Message: ', eventData.Message, sep='')
        print('Event.Active: ', eventData.Active, sep='')
        print('Event.Acknowledged: ', eventData.Acknowledged, sep='')


# Instantiate the OPC-A&E client object.
aeClient = EasyAEClient()

# Instantiate the OPC-DA client object.
daClient = EasyDAClient()

#
aeClient.Notification += notification

print('Processing event notifications...')
subscriptionFilter = AESubscriptionFilter()
subscriptionFilter.Categories = [15531778]
# You can also filter using event types, severity, areas, and sources.
handle = IEasyAEClientExtension.SubscribeEvents(aeClient, '', 'OPCLabs.KitEventServer.2', 1000, None, subscriptionFilter)

# Allow time for initial refresh.
time.sleep(5)

# Set some events to active state.
try:
    IEasyDAClientExtension.WriteItemValue(daClient, '', 'OPCLabs.KitServer.2',
                                          'SimulateEvents.ConditionState1.Activate', True)
    IEasyDAClientExtension.WriteItemValue(daClient, '', 'OPCLabs.KitServer.2',
                                          'SimulateEvents.ConditionState2.Activate', True)
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message)
    exit()

time.sleep(10)

aeClient.UnsubscribeEvents(handle)
aeClient.Notification -= notification

print('Finished.')

 

Filtering by source or sources:

.NET

// This example shows how to set the filtering criteria to be used for the event 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 System.Threading;
using OpcLabs.EasyOpc.AlarmsAndEvents;
using OpcLabs.EasyOpc.AlarmsAndEvents.OperationModel;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.OperationModel;

namespace DocExamples.AlarmsAndEvents._AESubscriptionFilter
{
    class Properties
    {
        // Instantiate the OPC-A&E client object.
        static readonly EasyAEClient AEClient = new EasyAEClient();


        // Instantiate the OPC-DA client object.
        static readonly EasyDAClient DAClient = new EasyDAClient();

        public static void Main1()
        {
            var eventHandler = new EasyAENotificationEventHandler(aeClient_Notification);
            AEClient.Notification += eventHandler;

            Console.WriteLine("Processing event notifications...");
            var subscriptionFilter = new AESubscriptionFilter
            {
                Sources = new AENodeDescriptor[] { "Simulation.ConditionState1", "Simulation.ConditionState3" }
            };
            // You can also filter using event types, categories, severity, and areas.
            int handle = AEClient.SubscribeEvents("", "OPCLabs.KitEventServer.2", 1000, null, subscriptionFilter);

            // Allow time for initial refresh
            Thread.Sleep(5 * 1000);

            // Set some events to active state.
            try
            {
                // The activation below will come from a source contained in a filter and the notification will arrive.
                DAClient.WriteItemValue("", "OPCLabs.KitServer.2", "SimulateEvents.ConditionState1.Activate", true);
                // The activation below will come from a source that is not contained in a filter and the notification will not arrive.
                DAClient.WriteItemValue("", "OPCLabs.KitServer.2", "SimulateEvents.ConditionState2.Activate", true);
            }
            catch (OpcException opcException)
            {
                Console.WriteLine("*** Failure: {0}", opcException.GetBaseException().Message);
                return;
            }

            Thread.Sleep(10 * 1000);

            AEClient.UnsubscribeEvents(handle);
            AEClient.Notification -= eventHandler;
        }

        // Notification event handler
        static void aeClient_Notification(object sender, EasyAENotificationEventArgs e)
        {
            Console.WriteLine();
            if (!e.Succeeded)
            {
                Console.WriteLine("*** Failure: {0}", e.ErrorMessageBrief);
                return;
            }

            Console.WriteLine("Refresh: {0}", e.Refresh);
            Console.WriteLine("RefreshComplete: {0}", e.RefreshComplete);
            AEEventData eventData = e.EventData;
            if (!(eventData is null))
            {
                Console.WriteLine("Event.QualifiedSourceName: {0}", eventData.QualifiedSourceName);
                Console.WriteLine("Event.Message: {0}", eventData.Message);
                Console.WriteLine("Event.Active: {0}", eventData.Active);
                Console.WriteLine("Event.Acknowledged: {0}", eventData.Acknowledged);
            }
        }
    }
}

COM

Rem This example shows how to set the filtering criteria to be used for the event 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

Dim DAClient: Set DAClient = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
Dim AEClient: Set AEClient = CreateObject("OpcLabs.EasyOpc.AlarmsAndEvents.EasyAEClient")
WScript.ConnectObject AEClient, "AEClient_"

WScript.Echo "Processing event notifications..."
Dim ServerDescriptor: Set ServerDescriptor = CreateObject("OpcLabs.EasyOpc.ServerDescriptor")
ServerDescriptor.ServerClass = "OPCLabs.KitEventServer.2"
Dim SubscriptionFilter: Set SubscriptionFilter = CreateObject("OpcLabs.EasyOpc.AlarmsAndEvents.AESubscriptionFilter")
Dim SourceDescriptor1: Set SourceDescriptor1 = CreateObject("OpcLabs.EasyOpc.AlarmsAndEvents.AENodeDescriptor")
SourceDescriptor1.QualifiedName = "Simulation.ConditionState1"
Dim SourceDescriptor2: Set SourceDescriptor2 = CreateObject("OpcLabs.EasyOpc.AlarmsAndEvents.AENodeDescriptor")
SourceDescriptor2.QualifiedName = "Simulation.ConditionState3"
SubscriptionFilter.Sources = Array(SourceDescriptor1, SourceDescriptor2)
Rem You can also filter using event types, categories, severity, and areas.
Dim SubscriptionParameters: Set SubscriptionParameters = CreateObject("OpcLabs.EasyOpc.AlarmsAndEvents.AESubscriptionParameters")
SubscriptionParameters.Filter = SubscriptionFilter
SubscriptionParameters.NotificationRate = 1000
Dim handle: handle = AEClient.SubscribeEvents(ServerDescriptor, SubscriptionParameters, True, Nothing)

Rem Allow time for initial refresh
WScript.Sleep 5*1000

WScript.Echo "Set some events to active state..."
On Error Resume Next
Rem The activation below will come from a source contained in a filter and the notification will arrive.
DAClient.WriteItemValue "", "OPCLabs.KitServer.2", "SimulateEvents.ConditionState1.Activate", True
Rem The activation below will come from a source that is not contained in a filter and the notification will not arrive.
DAClient.WriteItemValue "", "OPCLabs.KitServer.2", "SimulateEvents.ConditionState2.Activate", True
If Err.Number <> 0 Then
    WScript.Echo "*** Failure: " & Err.Source & ": " & Err.Description
    WScript.Quit
End If
On Error Goto 0

WScript.Sleep 10*1000

WScript.Echo "Unsubscribing..."
AEClient.UnsubscribeEvents handle



Rem Notification event handler
Sub AEClient_Notification(Sender, e)
    If Not (e.Succeeded) Then
        WScript.Echo "*** Failure: " & e.ErrorMessageBrief
        Exit Sub
    End If

    WScript.Echo 
    WScript.Echo "Refresh: " & e.Refresh
    WScript.Echo "RefreshComplete: " & e.RefreshComplete

    If Not (e.EventData Is Nothing) Then
        With e.EventData
            WScript.Echo "EventData.QualifiedSourceName: " & .QualifiedSourceName
            WScript.Echo "EventData.Message: " & .Message
            WScript.Echo "EventData.Active: " & .Active
            WScript.Echo "EventData.Acknowledged: " & .Acknowledged
        End With
    End If
End Sub

Python

# This example shows how to set the filtering criteria to be used for the event 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 import *
from OpcLabs.EasyOpc.AlarmsAndEvents import *
from OpcLabs.EasyOpc.DataAccess import *
from OpcLabs.EasyOpc.OperationModel import *


# Notification event handler
def notification(sender, e):
    if not e.Succeeded:
        print('*** Failure: ', e.ErrorMessageBrief, sep='')
        return
    print('Refresh: ', e.Refresh, sep='')
    print('RefreshComplete: ', e.RefreshComplete, sep='')
    eventData = e.EventData
    if eventData is not None:
        print('Event.QualifiedSourceName: ', eventData.QualifiedSourceName, sep='')
        print('Event.Message: ', eventData.Message, sep='')
        print('Event.Active: ', eventData.Active, sep='')
        print('Event.Acknowledged: ', eventData.Acknowledged, sep='')


# Instantiate the OPC-A&E client object.
aeClient = EasyAEClient()

# Instantiate the OPC-DA client object.
daClient = EasyDAClient()

#
aeClient.Notification += notification

print('Processing event notifications...')
subscriptionFilter = AESubscriptionFilter()
subscriptionFilter.Sources = [
    AENodeDescriptor('Simulation.ConditionState1'),
    AENodeDescriptor('Simulation.ConditionState3'),
]
# You can also filter using event types, categories, severity, and areas.
handle = IEasyAEClientExtension.SubscribeEvents(aeClient, '', 'OPCLabs.KitEventServer.2', 1000, None, subscriptionFilter)

# Allow time for initial refresh
time.sleep(5)

# Set some events to active state.
try:
    # The activation below will come from a source contained in a filter and the notification will arrive.
    IEasyDAClientExtension.WriteItemValue(daClient, '', 'OPCLabs.KitServer.2', 'SimulateEvents.ConditionState1.Activate', True)
    # The activation below will come from a source that is not contained in a filter and the notification will not
    # arrive.
    IEasyDAClientExtension.WriteItemValue(daClient, '', 'OPCLabs.KitServer.2', 'SimulateEvents.ConditionState2.Activate', True)
except OpcException as opcException:
    print('*** Failure: ' + opcException.GetBaseException().Message)
    exit()

time.sleep(10)

aeClient.UnsubscribeAllEvents()
aeClient.Notification -= notification

print('Finished.')

 

 

See Also