ALr 39 – How the 'Grace Time – Lockout Time' alarm works
When the SCS Controller is not connected to an application within the Run – Lockout Time period, and a subsequent keypad password entry grants a grace period that also expires without an application connection, the controller turns off all outputs and triggers an ALr 39 alarm.
What happened?
This alarm occurs in two stages:
- The controller was not connected to an application within the Run – Lockout Time period, triggering an ALr 38 alarm and shutting off all outputs.
- The controller was then reactivated via a keypad password, which started an additional grace period (the Grace – Lockout Time).
The controller was still not connected to an application before the grace period expired — so all outputs have been turned off again.
Possible causes and actions
- The controller has reached the end of its Grace – Lockout Time without receiving a connection from an SCS application. As a result, the controller has turned off all outputs.
- Connect to the controller using any SCS application (such as Field or Track) to reset the timer and restart normal operation.
Note: Unlike ALr 38, there is no further keypad-based grace period available at this stage. An application connection is required to restore operation.
When the SCS Controller is not connected to an application within the Run – Lockout Time period, and a subsequent keypad password entry grants a grace period that also expires without an application connection, the controller turns off all outputs and triggers an ALr 39 alarm.
How ALr 38 and ALr 39 work together
Fault Reference
ALr 38 & ALr 39 · Lockout Timers
SCS Controller
Normal Operation
ALr 38
Grace Period
ALr 39