4.3.6 Blocking Alarms

The alarm may be masked during start up. Blocking prevents the alarm from being activated until the process has first achieved a safe state. It is used, for example, to ignore start up conditions which are not representative of running conditions. Blocking is re-instated after a power cycle or when going from configuration level to an operating level.

 

Blocking alarms may be configured using ‘P’ codes P23, P26 and P29.

 

It is possible to mix blocking alarms with any of the latching types listed above. Each alarm so configured will behave independently.

 

Alarm 2 is not available with the blocking alarm feature in FM approved versions (816L, 808L, 804L).

 

☻ ‘P’ codes are found in section 5.2.