ISA type alarm means an alarm that must follow all three event changes indicated below:
ALARM ON
The alarm is activated according to the mode defined in the specific programming.
ALARM OFF
The alarm is deactivated as the triggering condition is no longer present
Acknowledge
The alarm must be silenced (acknowledged) by the operator according to one of the modes programmed in the application.
When the ISA type alarm has satisfied all 3 of the previously defined status changes, it is removed from the active alarm buffer.
However, all the status changes remain in the alarm history buffer.
When does an alarm ISA have to be used
It should be used when you want to be sure that the operator has realized that an alarm has been triggered.
In fact, the alarm is not removed until it is acknowledged by the operator.
