Server current-State Model with Suppression – OPC Unified Architecture

B.1.4 Server current-State Model with Suppression

This example adds additional fields to the model illustrated in B.1.2. This example does not use acknowledge or confirm – it assumes that the alarm is automatically acknowledged (and does not support confirm). It does add OutOfServiceState and SuppressedState.

Figure B.3 shows an Alarm as it becomes active, is suppressed or is placed out of service and then inactive. Table B.3 lists the values of the state Variables. All Events are coming from the same Condition instance and therefore have the same ConditionId. The Client subscription includes an event filter that excludes suppressed or out of service conditions (i.e. SuppressedState = True or OutOfServiceState = True). The events shown in green are delivered to the Client. The Retain column indicates the global value of the Retain flag. The “Retain sent” column indicates the overridden value sent in a notification if SupportsFilteredRetain is True. If SupportsFilteredRetain is False the value from the Retain column is sent.

Figure B.3 – SuppressedState and OutOfServiceState example

Table B.3 – Example of a Condition that is Suppressed / OutOfService

EventId	Active	Suppressed State	OutOf Service State	Retain	Retain sent	Event Deliver with Filter	Description
-*)	False	False	False	False	False	-	Initial state of Condition.
1	True	False	False	True	True	Yes	Alarm goes active.
2	True	False	True	True	False	Yes	Placed OutOfService
3	True	True	True	True	False	No	Alarm Suppressed; No event since OutOfService
4	False	True	True	False	False	No	Alarm goes inactive; No event since OutOfService
5	False	False	True	False	False	No	Alarm not Suppressed; No event since not active
6	True	False	True	True	False	No	Alarm goes active; No event since OutOfService
7	True	False	False	True	True	Yes	Alarm no longer OutOfService; Event generated
8	False	False	False	False	False	Yes	Alarm goes inactive
9	False	True	False	False	False	No	Alarm Suppressed; No event since not active
10	True	True	False	True	False	No	Alarm goes active; No event since Suppressed
11	False	True	False	False	False	No	Alarm goes inactive; No event since Suppressed
12	False	False	False	False	False	No	Alarm no longer Suppressed
13	False	False	True	False	False	No	Placed OutOfService
14	True	False	True	True	False	No	Alarm goes active; No event since OutOfService
15	False	False	True	False	False	No	Alarm goes inactive; No event since OutOfService
16	False	False	False	False	False	No	Alarm no longer OutOfService

This behaviour occurs when the implementation supports SupportsFilteredRetain flag subscription.