Led Functions; Csu Loop Operation - TC Communications TC8612 User Manual

B R2 Button & LED Functions
B.2

LED Functions

RMT: displays the remote unit's LED status on the local unit
BPV: displays bi-polar violation(s) for the ingress T1/E1 signal
CRC: displays error(s) in data integrity (only for T1 ESF frame and E1 built-in
CRC)
SYNC: displays frame locking for T1 (ESF framing) or E1 (PCM31C framing)
The alarm LEDs - BPV, CRC and SYNC - all have a latching functionality to
indicate the number of occurrences for each error. These LEDs will continuously
flash at regular intervals until reset by the user. The behavior is noted here:
• When an LED blinks once, it indicates a single error has occurred once. When
an LED blinks twice, it indicates the error has occurred twice. When the LED
blinks 3 times, it indicates the error has occurred 3 or more times.
B.3

CSU Loop Operation

When the ISP transmits the CSU Loop Up Code towards the unit, the unit will
recognize the code and loop back the entire T1/E1 signal back towards the ISP.
Once the Loop Up condition is established, the unit alarm will be flashing and the
ISP may perform BER testing and other tests on the looped link.
To cancel the loop, the ISP must transmit the CSU Loop Down Code towards the
unit. Alternatively, disconnecting the T1/E1 cable will also cancel the loop.
B-2
LED Functions
TC8612 Rev 1.1 User Manual