ADTRAN HDSL2 - Manual (Page 71)

HDSL2 for General Distribution Installation and Maintenance Practice HDSL2 Loopback and Control Codes
61223HDSL2L2-5B A-3
Table A-2. In-Band Addressable Loopback Codes
(All codes listed below must be sent for a minimum of 5 seconds in order for them to be detected and acted upon.)
Function Code Source Code and Response
Arm 11000 (2-in-5 pattern) (N) If the pattern is sent from the network, the units
arm, and the H2TU-R loops back if Smartjack Loop-
back is enabled.
Disarm 11100 (3-in-5 pattern) (N/C) The H2TU-C is removed from the armed state. Any
units in loopback when the 11100 pattern is
received loop down. The
LBK
LEDs extinguish on all
units.
H2TU-C
Network
Loopback D3D3
(1101 0011 1101 0011) (N) If the units have been armed and no units are in
loopback, the H2TU-C loops back toward the net-
work, 2 seconds of AIS (all ones) are sent, 5 seconds
of data pass, and then 231 bit errors are injected
into the DSX-1 signal. As long as the pattern contin-
ues to be sent, 231 errors are injected every 20 sec-
onds. When the pattern is removed, the unit remains
in loopback. If the pattern is reinstated, the injection
of 231 bit errors resumes at 20-second intervals.
If Smartjack Loopback is enabled, then the H2TU-R
can be in network loopback when the H2TU-C loop-
up codes are sent.
HRE
Network
Loopback C741
(1100 0111 0100 0001) (N) If an HRE is present, the units have been armed, the
HRE loops back towards the network, 2 seconds of
AIS (all 1s) are sent, 5 seconds of data pass, and
then 10 bit errors will be injected into the DSX-1 sig-
nal. As long as the pattern continues to be sent, 10
bit errors are injected every 20 seconds. When the
pattern is removed, the unit remains in loopback. If
the pattern is reinstated, the injection of 10 bit
errors resumes at 20-second intervals.
H2TU-R
Loopback C742
(1100 0111 0100 0010) (N) When set from the network, an HTU-R network loop-
back is activated and a 20-bit error confirmation is
sent every 10 seconds.
Loop
Down 9393
(1001 0011 1001 0011) (N) When sent from the network, all units currently in
loopback loop down. Armed units do not disarm. In
order to behave like a smartjack, the H2TU-R does
loop down from a network loopback in response to
the 9393 pattern, if Smartjack Loopback is enabled.