The console has 2 red LEDs, labeled ALM and ACK. The left LED lights steadily when there is a Major
or Minor alarm at the switch cabinet. The right LED lights steadily if the alarm has been successfully
reported to INADS. If the system is unable to report the alarm to INADS, the LED flashes, thus signaling
the attendant to call INADS and report the alarm. The system calls INADS automatically if it uses a
modem.

Other circuit packs

Upon power up, some LEDs may be lit on the other circuit packs. Under normal operation, LEDs on
these circuit packs should not light, with the following exception – a solid green LED on any circuit pack
indicates that diagnostic tests are being executed on that circuit pack.

Circuit packs’ status LEDs

Each circuit pack has 3 LEDs on the front panel visible at the front of the carrier. On every circuit pack,
except the 650A power unit, the LEDs indicate:

•

Red (alarm) – If the circuit pack is communicating with the system, the system has detected a
fault in this circuit pack. An on-board alarm for this circuit pack is displayed in the Alarm Log.

The circuit pack also lights this LED when either the circuit pack has not yet initialized
communication with the system or when the circuit pack loses contact with the system and stops
functioning (circuit pack is said to be “in reset”). In these cases, there may not be an alarm in the
Alarm Log. To determine if the red LED is lit because the circuit pack is not in contact with the
system, issue the list configuration board PCSS command, where PCSS refers to the slot
containing this circuit pack. If the system does not detect the circuit pack, this command returns
Identifier not assigned or no board.