ADTRAN 1247026L1, Installation And Maintenance Manual

Page: 39 / 50

HDSL System Testing
61247026L1-5A 31
T200 HTU-R, SP/60 mA Loopbacks
The T200 HTU-R, SP/60 mA responds to two different loopback activation processes. First,
loopbacks may be commanded manually using the control port interface.
Figure 10 depicts
the Loopback Options Screen which provides for HTU-C, T200 HTU-R, SP/60 mA, and HRE
loopbacks.
Second, the T200 HTU-R, SP/60 mA responds to the industry standard sequences for HDSL
loopbacks. These loopback sequences are described in detail in
“Appendix A, HDSL Loopbacks” .
The loopback condition imposed in both cases is a logic level loopback at the point within the
T200 HTU-R, SP/60 mA where the DSX-1 signal passes into the HDSL modulators.
Figure 18
depicts all the loopback locations possible with ADTRAN HDSL equipment.
In addition to network-side loopbacks, the T200 HTU-R, SP/60 mA provides customer-side
loopbacks initiated by using the terminal control port. In this mode, an AIS signal is supplied
to the network. Customer-side loopbacks must be deactivated using the terminal.
NOTE
When the 11000 in-band code is used to loop the T200 HTU-R, SP/60
mA, the T200 HTU-R, SP/60 mA will re-enter armed state upon
loopback timeout, or upon terminal deactivation. See
“Appendix A,
HDSL Loopbacks” for a more detailed description of loopback element
states.
Front Panel Pushbuttons
Two loopback (
LBK
) buttons are accessible from the front panel. The
REM
loopback button controls
a customer loopback at the T200 HTU-R, SP/60 mA. The
LOC
loopback button controls a bidirec-
tional loopback at the T200 HTU-R, SP/60 mA. Refer to Table 14 for details.
Table 14. T200 HTU-R, SP/60 mA Front Panel Pushbuttons
Pushbutton Function
REM Pressing this button changes the T200 HTU-R, SP/60 mA customer loopback
state as follows:
• If the T200 HTU-R, SP/60 mA is not in loopback, pressing
REM
activates a
customer loopback.
• If the T200 HTU-R, SP/60 mA is in loopback, pressing
REM
deactivates the loopback.
LOC
Pressing this button changes the T200 HTU-R, SP/60 mA bidirectional loopback
state as follows:
• If the T200 HTU-R, SP/60 mA is not in loopback, pressing
LOC
activates
the bidirectional loopback.
• If the T200 HTU-R, SP/60 mA
is in loopback, pressing
LOC
deactivates
the bidirectional loopback.