EventNotifier and source hierarchy|OPC UA Standard|Forum|OPC Foundation

For “1”- the Server Object is required to provided all Events/Alarms generated in the server, it does not need any references.

for “2” &”3″  Is the Master Object configured to be a notifier – i.e. does the master object have the EventNotifier bit set to true, so a client can subscribe to events from the master object directly?  if the master Object is an event source, then providing the HasCondition reference to the Master_Condition object make sense.  The Port_1_condition could be model in more ways, the Port_1 object could be an EventNotifier and have a HasNotifier refernce between it and the Master object, in which case the HasCondition reference would exist between the Port_1 object and the Port_1_condition Object.  If the notifier tree does not exist then the master object would have a HasEventSource Reference to Port_1 object, which would have the HasCondition Refeence [At least I’m assumming in your example that the Port_1_condition is nto really associated with the Master but with the Port.  when a client is looking for event related information it browses along these reference types, not the HasComponent references.

Paul

Using the HasComponent reference is not incorrect, the model as you depicted it in the original question can be fine, if that is what the device model is suppose to look like.

What is important with respect to alarms is the HasNotifier, HasEventSource, HasCondition reference that are used b the model.  Say I have  machine that has two motors in it and another machine that has three motors in it.  I also have a controller that is not part of either machine.  The object models for the machine have a hierarchy that includes the motors, the control has its own model.  But The controller also reports all alarms related to the motors, so it has HasNotifier references  to the motors, and the motor may have a HasCondition reference to the Conditions the motor could report (say speed alarms), In addition the Machine has a temperature sensor that is part of machine, and the motor can have a HasEventSource reference to the sensor to report the alarm associate with temperate since that can effect the motor behavior (the temperature alarms might also be reports in another alarm stream).

[Note: in many implementations alarm instance do not exist in the server.  Say an Object could report 10 different alarms, and the server has several hundred of these objects, the number of alarm instance grows very fast.  Most of these Alarm instance will never occur or be used (since say 1 or 2 of them are all that might be active at the same time)  So the Server maintains the Alarms in separate code, the information model only indicates what alarm the object can generate (points to types).  The Alarm instance behavior is handled in code, when an alarm occurs (dynamically created as needed) – this all has to do with what is desire, what the server capabilities are etc.

Paul