The LEDs to the left of fiber optic ports are indicators for “Channel 0”.
The LEDs to the right of fiber optic ports are indicators for “Channel 1”.
LA
Local Alarm. A red LED indicating that the 21-219 has encounter a fault in the
received IEEE C37.94 protocol – LOS Loss Of Signal. The “Yellow Alarm bit” is
set in the outgoing IEEE C37.94 protocol.
Is red when the 21-219 has detected an error. This indication has a memory function.
When the local-error is no longer present, the LA-LED will be blink until “Reset”-
button is pressed.
RA
Remote Alarm. A red LED indicating that the remote unit has encounter a fault
condition and has set the “Yellow Alarm bit” in the IEEE C37.94 protocol.
Is red when the remote unit of the fiber optic link has detected an error. This
indication has a memory function. When the remote-error is no longer present, the
RA-LED will be blink until “Reset”-button is pressed.
St
Status. A red LED is lit when the 21-219 has set outgoing data on fiber to AIS-
condition
LI
Link Fiber. A green LED indicating that the 21-219 receives correct IEEE C37.94
frames, (no LOS). Blinks when fiber optic receiver indicate low signal amplitude.
Low amplitude is indicated when received optical signal power is between -35dBm
and -40dBm.
The IEEE C37.94 standard specifies:
“The receiver shall operate error-free
(BER <1E –9) for mean optical power between –32 dBm and –11 dBm.“
TxD
Received data from E1 sent out to IEEE C37.94. A yellow LED indicating that 21-
219 sends data in IEEE C37.94 format.
RxD
Receive IEEE C37.94 data on fiber. A yellow LED indicating that 21-219 receives
data in IEEE C37.94 protocol.
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