# 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)