Before sending an alarm, iFIX compares the alarm priority of each alarm against the SCADA server's alarm priority. If the alarm's priority is equal to or higher than the SCADA server's priority, iFIX sends the alarm to the enabled alarm destinations in the specified alarm areas. However, if the alarm's priority is less than the SCADA server's, iFIX automatically acknowledges the alarm and does not send to the enabled alarm destinations.
If multiple alarms occur simultaneously, the lower priority alarm type is ignored. In this case, the Analog Alarm block closes any contacts defined for the lower priority alarms, but does not send alarms. When the block detects an alarm condition and no other alarms of greater priority are in effect, the block generates an alarm and closes the digital block defined in the Contact Name field.
NOTE: It is possible to close more than one digital block if the alarm type increases in priority without returning to normal. For example, if the block generates a Rate of Change alarm, it closes the digital block specified in the Rate of Change alarm's Contact Name field. If the block then generates a High alarm, it closes the digital block in the High alarm's Contact Name field.
Example
If you assign a high priority to a deviation alarm and a low priority to a High High alarm, iFIX treats deviation alarms as more severe than High High alarms. If Deviation and High High alarm conditions are simultaneously active, Data links that reference the current and latched alarms display DEV because the deviation alarm has greater priority.
Assigning the same priority to both the Deviation and High High alarms causes iFIX to treat the alarms according to the default order of alarm types.
NOTE: The alarm priority of the High alarm must be equal to or less than the priority of the High High alarm. Similarly, the alarm priority of the Low alarm must be equal to or less than priority of the Low Low alarm.
iFIX automatically acknowledges any alarm below the computer's alarm priority. This means that if the associated contact is set to clear on Acknowledge, it opens when iFIX acknowledges the alarm. Contacts set to clear in All Clear mode open when the block value falls within defined limits.
