Throttle alarms

Alarm throttling prevents network and message queues from flooding during periods of high alarm activity. Throttling sets a maximum number of transitions into and out of an alarm state within a defined period. Alarm transitions that exceed the throttling limit are not reported.

The WinPlatform object includes tuning parameters that specify the maximum alarm rate per second on an engine. The Alarm throttle limit attribute must be used in conjunction with the scan period to determine the maximum number of alarms that can occur in a scan cycle. You can set the alarm throttle limit when you configure the WinPlatform object. For more information about setting the scan period and alarm throttle limit, see Configure WinPlatform object alarms.

Alarm messages can be throttled for alarms going into alarm and out of alarm state. Alarm acknowledgement messages are not throttled. Users can still acknowledge alarms even when alarm throttling is active. Users can still disable alarms for objects or areas when the alarm rate causes throttling to occur. Also, the alarm inhibit and the disable/enable/silence messages are not throttled.

If an active alarm is disabled, the going out of alarm and disabled messages are sent to the notification distributor. If alarms are being throttled, the going out of alarm message can be throttled. The disabled message is accepted regardless of the throttling status. The going out of alarm message is not raised again. This can result in never logging a message for that alarm indicating it went out of alarm. The final alarm list in the Notification Distributor still shows the correct alarm state.