Examples for OPC client and subscriber development in Python are now on GitHub: github.com/OPCLabs/Examples-QuickOPC-Python .

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!

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

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.

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

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.