ADTRAN T200 H4TU-R Installation And Maintenance Practice page 24

Function
1
Span Power Disable
1,2
First H4R Loop Up
1,2
Second H4R Loop Up
H4TU-R Address 20 for
1,2
Extended Demarc
1. Units must be armed with 11000b or FF48h before this code will work.
2. Loopback and error injection will only occur if the in-band code is received by the unit that is to go into loopback. In
other words, if another loopback blocks the in-band code from being transmitted to the unit that is to go into loop-
back, loopback and error injection will not occur.
Note: All codes listed above must be sent for a minimum of 5 seconds to be detected and acted upon
A-4
Table A-2. Loopback Control Codes (Continued)
Code (Hex / Binary)
6767 or
0110 0111 0110 0111
C741
1100 0111 0100 0001
C754
1100 0111 0101 0100
C742
1100 0111 0100 0010
Issue 1, December 2003
Response
If the units are armed and 6767 is sent from the network, the
H4TU-C will disable span power. If the pattern is sent from
the network, the span power will be disabled as long as 6767
pattern is detected. Once the pattern is no longer received, the
H4TU-C will reactivate span power. All units will then retrain
and return to the disarmed and unlooped state.
If one or more H4Rs are present, the H4R closest to the
H4TU-C will loop up toward the network, 2 seconds of AIS
(all ones) will be transmitted, the looped data will be sent for 5
seconds, and then a burst of 10 logic errors will be injected.
The burst of 10 logic errors will continue every 20 seconds as
long as the C741 pattern is detected. When the pattern is
removed, the unit will remain in loopback. If the pattern is
reinstated, the injection of 10 logic errors will continue every
20 seconds.
If two H4Rs are present, the second H4R from the H4TU-C
will loop up toward the network, 2 seconds of AIS (all ones)
will be transmitted, the looped data will be sent for 5 seconds,
and then a burst of 200 logic errors will be injected. The burst
of 200 logic errors will continue every 20 seconds as long as
the C754 pattern is detected. When the pattern is removed, the
unit will remain in loopback. If the pattern is reinstated, the
injection of 200 logic errors will continue every 20 seconds.
If armed, the H4TU-R will loop up toward the network, 2
seconds of AIS (all ones) will be transmitted, the looped data
will be sent for 5 seconds, and then a burst of 20 logic errors
will be injected. The burst of 20 logic errors will continue
every 10 seconds as long as the C742 pattern is detected.
When the pattern is removed, the unit will remain in loopback.
If the pattern is reinstated, the injection of 20 logic errors will
continue every 10 seconds.
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