B Push Button & LED Functions
CSU Loop Operation
B-2
TC8619 Rev 1.1 User Manual
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.
