Specifications

FOM-E3, FOM-T3 Ver. 1.0 Alarm Relay 4-1
Chapter 4
Diagnostics and
Troubleshooting
4.1 Alarm Relay
FOM-E3 and FOM-T3 include a dry contact alarm relay port with a 9-pin connector
for sensing major and minor alarms.
• Major alarms are initiated when E3/T3 electrical input becomes lower than
G.703 electrical levels, or bit error rate at the fiber optic interface is 10
-6
or
worse.
• Minor alarms occur when an alarm indication signal (AIS) is received at the
E3/T3 electrical or fiber optic interfaces.
The dry contact port is normally open or normally closed depending on different
pins of the alarm relay port connector (see
Figure 4-1 ).
Alarm Connector
Minor-NO
1
2
6
4
5
9
Major-NO
Major Alarm Relay
Minor Alarm Relay
Minor-NC
Major-NC
Minor-COM
Major-COM
Figure 4-1. Alarm Relay Connector Pinout
The relay positions are shown in the non-energized state (alarm active).
Note