The following examples show the Eventflow for typical Alarmsituations. The tables list the value of state Variablesfor each Event Notification.

This example is for Serversthat do not support previous states and therefore do not create and maintain Branchesof a single Condition.

Figure B.1shows an Alarmas it becomes active and then inactive and also the acknowledgement and confirmation cycles. Table B.1lists the values of the state Variables. All Eventsare coming from the same Conditioninstance and therefore have the same ConditionId.

Figure B.1– Single state example

Table B.1– Example of a Condition that only keeps the latest state

EventId	BranchId	Active	Acked	Confirmed	Retain	Description
-*)	NULL	False	True	True	False	Initial state of Condition.
1	NULL	True	False	True	True	Alarmgoes active.
2	NULL	True	True	False	True	Conditionacknowledged Confirm required
3	NULL	False	True	False	True	Alarmgoes inactive.
4	NULL	False	True	True	False	Conditionconfirmed
5	NULL	True	False	True	True	Alarmgoes active.
6	NULL	False	False	True	True	Alarmgoes inactive.
7	NULL	False	True	False	True	Conditionacknowledged, Confirm required.
8	NULL	False	True	True	False	Conditionconfirmed.
*) The first row is included to illustrate the initial state of the Condition. This state will not be reported by an Event.

This example is for Serversthat are able to maintain previous states of a Conditionand therefore create and maintain Branchesof a single Condition.

Figure B.2illustrates the use of branches by a Serverrequiring acknowledgement of all transitions into Activestate, not just the most recent transition. In this example no acknowledgement is required on a transition into an inactive state. Table B.2lists the values of the state Variables. All Eventsare coming from the same Conditioninstance and have therefore the same ConditionId.

Figure B.2– Previous state example

Table B.2– Example of a Conditionthat maintains previous states via branches

EventId	BranchId	Active	Acked	Confirmed	Retain	Description
a)	NULL	False	True	True	False	Initial state of Condition.
1	NULL	True	False	True	True	Alarm goes active.
2	NULL	True	True	True	True	Condition acknowledged requires Confirm
3	NULL	False	True	False	True	Alarmgoes inactive.
4	NULL	False	True	True	False	Confirmed
5	NULL	True	False	True	True	Alarmgoes active.
6	NULL	False	True	True	True	Alarmgoes inactive.
7	1	True	False	True	True b)	Prior state needs acknowledgment. Branch #1 created.
8	NULL	True	False	True	True	Alarmgoes active again.
9	1	True	True	False	True	Prior state acknowledged, Confirm required.
10	NULL	False	True	True	True b)	Alarmgoes inactive again.
11	2	True	False	True	True	Prior state needs acknowledgment. Branch #2 created.
12	1	True	True	True	False	Prior state confirmed. Branch #1 deleted.
13	2	True	True	True	False	Prior state acknowledged, Auto Confirmed by system Branch #2 deleted. c)
14	NULL	False	True	True	False	No longer of interest.
a)The first rowis included to illustrate the initial state of the Condition. This state will not be reported by an Event. Notes on specific situations shown with this example: If the current state of the Conditionis acknowledged then the Ackedflag is set and the new state is reported (Event#2). If the Conditionstate changes before it can be acknowledged (Event#6) then a branch state is reported (Event#7). Timestamps for the Events #6 and #7 is identical. The branch state can be updated several times (Events #9) before it is cleared (Event#12). A single Conditioncan have many branch states active (Events #11) b)It is recommendedas in this table to leave Retain=True as long as there exist previous states (branches). c) The system Auto confirms this event, since a confirmation is that the operator has taken some action. The confirmation of the previous state (line 12) indicates that the operator has taken an action and this transition does not require a separate confirmation.

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 OutOfServiceStateand SuppressedState.

Figure B.3 shows an Alarmas 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 Eventsare coming from the same Conditioninstance and therefore have the same ConditionId. The Clientsubscription 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 Retainflag. The “Retain sent” column indicates the overridden value sent in a notification if SupportsFilteredRetainis True. If SupportsFilteredRetainis 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.

This example illustrates how on-delay, off-delay and alarm dead bands can be used to reduce the number of alarms that are generated / reported (see 5.8). It also illustrates how ReAlarmTimeis used to bring an alarm back up to an active state (see Figure B.4).

Some process values may have sudden jumps that are very brief and do not constitute an alarm. For example, a motor on start draws a large current, but quickly come back down. This is a normal motor current load, and should not be alarmed, but a sustained current load is a problem and should be alarmed, by configuring a OnDelaytime, the momentary spike will not generate an alarm, since the value has to be above the alarm threshold for the duration of OnDelay.

An AlarmDeadbandis used to keep a noise signal from generating multiple Alarm activations a signal once it crosses an alarm limit will not return to norm unless it drops below the limit by the amount of the deadband specified. In the example the process value is jumping up and down around the limit, but the alarm just remains in the same active or acknowledged state. The Alarm can have a deadband for each limit (High vs HighHigh) and these deadbands can be different.

The OffDelaycan also be used, much as the OnDelay, except it will keep a Value in alarm even if it drops below a limit, but only very briefly. Again, this setting is used to limit the number of alarms that occur in a system.

The ReAlarmTimeis used to ensure that actions are taken to correct the issue that generated an alarm. Some alarms are configured to generate a new alarm if they have been in an active state for the ReAlarmTimeperiod. The Alarm, goes back to an Unacknowledged state, as if it had just occurred.

Figure B.4- Alarm example - On Delay, Off Delay, ReAlarmTime