ALARMS, TROUBLESHOOTING & TESTING
18
4 ALARMS, TROUBLESHOOTING & TESTING
4. 1 Alarms
The Status LED on the DC3X00 rear panel shows a variety of alarm conditions as shown in
the table below.
Figure 4.1 Rear panel LED alarms
The definitions of each alarm and the unit’s reponse to them is tabulated below.
Figure 4.2 Alarm responses & definitions
Status LED
Meaning
Off
No mains power present
Red steady
LOS
Red/Off flashing
LOS and DTE Alarm
Red/Green flashing
LOF or AIS Alarm
Red/Green/Off flashing
AIS and DTE Alarm
Green/Red/Off flashing
LOF and DTE Alarm
Green/Off flashing
DTE Alarm
Green steady
Status OK
Alarm
Alarm Definition
Response
LOS
Loss Of Signal:
No data and therefore no clocking
information.
E1 port transmits RAI if in framed
mode. Indication
DE-ASSERTED
.
LOF
Loss Of Frame:
Clocking information is there but the
frame alignment pattern is faulty.
(Framed mode only)
E1 port transmits RAI if in framed
mode. Indication
DE-ASSERTED
.
AIS
Alarm Indication Signal:
All 1’s being received.
E1 port transmits RAI if in framed
mode. Indication
DE-ASSERTED
.
RAI
Remote Alarm Indication:
RAI signal being received
(Framed mode only)
No response.
DTE
DTE Control signal absent
No response
