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SubscribeMultiple Example using Python

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20 Feb 2024 17:44 #12571 by support
Examples for OPC client and subscriber development in Python are now on GitHub: github.com/OPCLabs/Examples-QuickOPC-Python .

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21 Nov 2023 13:25 #12386 by support
Note: QuickOPC now supports Python in much better way, cleaner syntax, and public packages (pypi.org/project/opclabs-quickopc/) on Python Package Index . See What's new in QuickOPC 2023.2 for more information. And, over 270 examples are available in the User's Guide!

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10 Feb 2023 08:41 #11529 by support
Hello,

here it is:

 
# This example shows how to subscribe to changes of multiple monitored items, pull events, and display each change.
 
import time
import win32com.client
 
# Instantiate the client object
client = win32com.client.Dispatch('OpcLabs.EasyOpc.UA.EasyUAClient')
# In order to use event pull, you must set a non-zero queue capacity upfront.
client.PullDataChangeNotificationQueueCapacity = 1000
 
print('Subscribing...')
monitoringParameters = win32com.client.Dispatch('OpcLabs.EasyOpc.UA.UAMonitoringParameters')
monitoringParameters.SamplingInterval = 1000
monitoredItemArguments1 = win32com.client.Dispatch('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'
monitoredItemArguments1.MonitoringParameters = monitoringParameters
monitoredItemArguments2 = win32com.client.Dispatch('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'
monitoredItemArguments2.MonitoringParameters = monitoringParameters
monitoredItemArguments3 = win32com.client.Dispatch('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'
monitoredItemArguments3.MonitoringParameters = monitoringParameters
arguments = [
monitoredItemArguments1,
monitoredItemArguments2,
monitoredItemArguments3
    ]
client.SubscribeMultipleMonitoredItems(arguments)
 
print('Processing data change events for 1 minute...')
endTime = time.time() + 60
while time.time() < endTime:
eventArgs = client.PullDataChangeNotification(2*1000)
    if eventArgs is not None:
    # Handle the notification event
    print(eventArgs)
 
 


Best regards

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09 Feb 2023 20:09 #11528 by jgonzalez
Hello,

Thank you for getting back to me so Promptly. The customer is working on an OPC UA Client application. My apologies for not sharing this with you in my initial message.

Best regards,

John G.

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09 Feb 2023 20:06 #11527 by support
Hi John,
is this meant for OPC UA, or for OPC Classic?

(I do not have either example, but will try to put it together tomorrow)

Best regards

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09 Feb 2023 15:25 #11524 by jgonzalez
Hello,

I have a customer that is working on a client application using Python. The customer is requesting an example of "Subscribe to Multiple".

Our team's knowledge of the python language is very limited and from experience, we have not come across much use from customers.

Our question to you is, do you happen to have any example code for "Subscribe to Multiple" using python?

Your guidance is greatly appreciated.

Best regards,

John G.

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