Understanding the EventFilter / QualifiedName

[dev-chris13]

Hi!

I am currently trying to build a client that collects specific events via an event subscription. I am struggling to understand the string part of the QualifiedName. I am not sure how to map it to things I see the UAExpert.

I am instressed in events of the Type AlarmConditionType and I need to know the TransitionTime of the ActiveState. What would be the QualifiedName for the TransitionTime?
This are the relationships between these elements:
AlarmCondtionType –hasComponent--> ActiveState --hasProperty--> TransitionTime

Another example would be the TransitionTime of the LastTransition of the ShelvingState:
AlarmCondtionType –hasComponent--> ShelvingState -- hasComponent --> LastTransition --hasProperty--> TransitionTime

Thanks in advance for your help!
Best,
Chris

[dev-chris13]

Found the solution.

If anyone has the same question:

Use the BrowseName as string part of a QulifiedName. Provide a list of QulifiedNames as relative path / browsPath to the node of interest (https://reference.opcfoundation.org/v104/Core/DataTypes/SimpleAttributeOperand/)

Thanks for giving me a space to think "loud".

[kevinherron]

@dev-chris13 glad you figured it out. I’ve been away on vacation the last week and just now checking my email etc…

[dev-chris13]

Hi Kevin! Thanks for getting back to me! Hope you had a great vacation.

I still have one question: is it possible to read the other elements of value, e.g., Source timestamp?

[kevinherron]

If an event has a "Value" property, and you subscribed to it, you would receive a DataValue that has those components in it (value, StatusCode, server/source timestamps if available). You wouldn't ask for these components independently.

[dev-chris13]

I checked by comparing the ManagedSubscriptionDataExample and the ManagedSubscriptionEventExample with the ProSysSimulationServer.
When looking at the values in the ManagedSubscriptionDataExample I can find the complete structure of the DataValue and all required information:

When trying the same for the eventFieldValues in the ManagedSubscriptionEventExample I cannot find this structure which is available according to the UAExpert:

Thanks again!

[kevinherron]

Event items and data items are two different things. If you want to subscribe to a a VariableNode’s Value attribute you probably need a regular data MonitoredItem, not an event MonitoredItem.