ADTRAN H2TU-C Installation And Maintenance Practice page 29

Table A-1. In-Band Addressable Loopback Codes (Continued)
Function/Code
Query Loopback/D5D5
(1101 0101 1101 0101)
Query Loop Parameters/DBDB
(1101 1011 1101 1011)
Loopback Time Out Override/D5D6
(1, 2, 5)
(1101 0101 1101 0110)
Span Power Disable/6767
(0110 0111 0110 0111)
Note: All codes listed above must be sent for a minimum of 5 seconds in order for them to be detected and acted
upon.
1. The H2TU-C and H2TU-R individually detect and act upon in-band loopback control codes. Depending on
which list number of H2TU-R is used with the Litespan H2TU-C, some of these control codes may not cause
action (such as loop up, error injection, etc.) at the H2TU-R. Refer to the H2TU-R documentation for
supported control codes.
2. Modules must be armed with 11000b or FF48h for this code to function.
3. If NIU is enabled, then the H2TU-R can be in network loopback when the H2TU-C or H2R loop up codes are
sent.
4. In order to behave like a NIU, the H2TU-R can not loop down from the network side with 9393h.
5. This code can be detected only if the modules are armed OR if any loopbacks are active.
61221002L1-5F
Response
If the modules are armed and the H2TU-C or H2TU-R are in
(1, 2)
network loopback, errors are injected into the DSX-1 signal
upon detection of the query loopback pattern. As long as the
pattern continues to be sent, errors are injected again every
20 seconds. The number of errors injected each time
depends on which unit is in loopback. 231 errors are
injected if the
H2TU-C is in network loopback and 20 at a time if the
H2TU-R is in network loopback.
If the units are armed and the H2TU-C is in network
(2)
loopback, errors are injected into the DSX-1 signal upon
detection of the query loop parameters pattern. As long as a
pattern continues to be sent, errors are injected again every
20 seconds.
The number of errors injected each time depends on the
current status of signal quality and pulse attenuation
parameters on each loop.
• 111 errors are injected if all HDSL2 receiver points
(H2TU-C, and H2TU-R) indicate pulse attenuation is 30
dB or lower and signal quality (margin) is 6 dB or higher.
• 11 errors at a time are injected if any of the receiver
points indicate pulse attenuation is greater than 30 dB
and/or signal quality (margin) is less than 6 dB.
If the units are armed and this pattern is sent, the loopback
time out is disabled. The time out option is updated to
on the PROVISIONING menu of the H2TU-R screens
(viewable through the RS-232 port). As long as the units
remain armed, the time out remains disabled. When the
units are disarmed, the loopback time out returns to the
value it had before the D5D6 code was sent.
If the units are armed and this pattern is sent, the H2TU-C
(1, 2, 5)
deactivate the span power supply, removing power to the
H2TU-R. As long as the pattern continues to be sent, the
span power supply remains disabled. When the pattern is
discontinued, the H2TU-C reactivates its span power
supply, returning power to the remote unit. All units retrain
and return to the disarmed and unlooped state.
Appendix A, HDSL2 Loopbacks - HDSL MAINTENANCE MODES
NONE
A-3