Examples - OPC Data Access - Subscribe to large number of items

.NET

C#
VB.NET

// This example shows how subscribe to large number of items.
//
// 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.DataAccess;
using OpcLabs.EasyOpc.DataAccess.OperationModel;

namespace DocExamples.DataAccess._EasyDAClient
{
    partial class SubscribeMultipleItems
    {
        public static void ManyItems()
        {
            // Instantiate the client object.
            using (var client = new EasyDAClient())
            {
                client.ItemChanged += client_ItemChanged_ManyItems;

                const int numberOfItems = 1000;

                Console.WriteLine("Preparing arguments...");
                var argumentArray = new DAItemGroupArguments[numberOfItems];
                for (int i = 0; i < numberOfItems; i++)
                {
                    int copy = (i / 100) + 1;
                    int phase = (i % 100) + 1;
                    string itemId = String.Format("Simulation.Incrementing.Copy_{0}.Phase_{1}", copy, phase);
                    argumentArray[i] = new DAItemGroupArguments("", "OPCLabs.KitServer.2", itemId, 50, null);
                }

                Console.WriteLine("Subscribing to {0} items...", numberOfItems);
                client.SubscribeMultipleItems(argumentArray);

                Console.WriteLine("Processing item changed events for 1 minute...");
                Thread.Sleep(60 * 1000);
            }
        }

        // Item changed event handler
        static void client_ItemChanged_ManyItems(object sender, EasyDAItemChangedEventArgs e)
        {
            if (e.Succeeded)
                Console.WriteLine("{0}: {1}", e.Arguments.ItemDescriptor.ItemId, e.Vtq);
            else
                Console.WriteLine("{0} *** Failure: {1}", e.Arguments.ItemDescriptor.ItemId, e.ErrorMessageBrief);
        }
    }
}

' This example shows how subscribe to large number of items.
'
' 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.Threading
Imports OpcLabs.EasyOpc.DataAccess
Imports OpcLabs.EasyOpc.DataAccess.OperationModel

Namespace DataAccess._EasyDAClient
    Partial Friend Class SubscribeMultipleItems
        Public Shared Sub ManyItems()
            Using client = New EasyDAClient()
                AddHandler client.ItemChanged, AddressOf client_ItemChanged_ManyItems

                Const numberOfItems As Integer = 1000

                Console.WriteLine("Preparing arguments...")
                Dim argumentArray = New DAItemGroupArguments(numberOfItems - 1) {}
                For i As Integer = 0 To numberOfItems - 1
                    Dim copy As Integer = (i \ 100) + 1
                    Dim phase As Integer = (i Mod 100) + 1
                    Dim itemId As String = String.Format("Simulation.Incrementing.Copy_{0}.Phase_{1}", copy, phase)
                    argumentArray(i) = New DAItemGroupArguments("", "OPCLabs.KitServer.2", itemId, 50, Nothing)
                Next i

                Console.WriteLine("Subscribing to {0} items...", numberOfItems)
                client.SubscribeMultipleItems(argumentArray)

                Console.WriteLine("Processing item changed events for 1 minute...")
                Thread.Sleep(60 * 1000)
            End Using
        End Sub

        ' Item changed event handler
        Private Shared Sub client_ItemChanged_ManyItems(ByVal sender As Object, ByVal e As EasyDAItemChangedEventArgs)
            ' Display the data
            If e.Succeeded Then
                Console.WriteLine("{0}: {1}", e.Arguments.ItemDescriptor.ItemId, e.Vtq)
            Else
                Console.WriteLine("{0} *** Failure: {1}", e.Arguments.ItemDescriptor.ItemId, e.ErrorMessageBrief)
            End If
        End Sub
    End Class
End Namespace

Python

Python (.NET)

# This example shows how subscribe to large number of items.
#
# 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.DataAccess import *
from OpcLabs.EasyOpc.DataAccess.OperationModel import *


# Item changed event handler.
def itemChanged(sender, e):
    if e.Succeeded:
        print(e.Arguments.ItemDescriptor.ItemId, ': ', e.Vtq, sep='')
    else:
        print(e.Arguments.ItemDescriptor.ItemId, ' *** Failure: ', e.ErrorMessageBrief, sep='')


NUMBER_OF_ITEMS = 1000

# Instantiate the client object.
client = EasyDAClient()

client.ItemChanged += itemChanged

print('Creating array of arguments...')
argumentArray = [None]*NUMBER_OF_ITEMS
for i in range(NUMBER_OF_ITEMS):
    copy = (i//100) + 1
    phase = i % 100
    itemId = 'Simulation.Incrementing.Copy_{}.Phase_{}'.format(copy, phase)
    print(itemId)
    #
    itemGroupArguments = DAItemGroupArguments('', 'OPCLabs.KitServer.2', itemId, 50, None)
    argumentArray[i] = itemGroupArguments

print('Subscribing to changes of ', NUMBER_OF_ITEMS, ' items...')
IEasyDAClientExtension.SubscribeMultipleItems(client, argumentArray)

print('Processing item change notifications for 1 minute...')
time.sleep(60)

print('Unsubscribing all items...')
client.UnsubscribeAllItems()

client.ItemChanged -= itemChanged

print('Finished.')

Concepts

Subscribing to OPC Classic Items