4.4.5 Latch reset
You can enable a Latch on most alarms. When an alarm with a Latch is activated, the alarm Action remains in force after the Alarm
condition clears. The latched alarm then requires acknowledgement and resetting to clear the alarm Action.
INFO
Alarm latching can provide an extra layer of safety for the system.
State B or C
Alarm
condition
clears?
No
Yes
Alarm
condition
reoccurs?
No
Yes
Operator action
Reset latch
Latched
alarm?
Yes
No
State A
Normal
State E or F
Acknowledge
alarm
State A
Normal
Acknowledge
alarm
The controller checks the Alarm
condition.
The controller checks whether the
alarm has a Latch enabled.
The latched alarm can be reset after
acknowledgment by the operator.
If the alarm condition reoccurs, the
alarm is activated again.
For example, you can configure a low oil pressure alarm with a latch enabled, with a Trip generator breaker and shutdown engine
alarm action and an Engine not running inhibit. If there is low oil pressure, the controller trips the breaker and shuts down the
engine. The engine remains stopped and will not be able to start until the operator acknowledges the alarm AND then resets the
latch.
Input
You can assign a function to reset latched alarms to an input under Configure > Input/output. Select the hardware module, then
select the input to configure.
DESIGNER'S HANDBOOK 4189340911K UK Page 108 of 521
To Next Page
Loading...
