Section 150-431-114
Release 01
Page 17
TABLE 2. HLU-431 GNLB TEST PROCEDURES
Step
Action
1
Have the CO tester send the HRU-412 (3 in 7) in-band loop-up code for five seconds. Observe that the
HLU-431, List 1D displays the “NREM” message indicating an HRU loopback is in effect (see Figure 6).
2
Have the CO tester transmit a DSX-1 test signal into the HLU-431, List 1D and verify that the returned
(looped) signal is error free.
3
If the above test fails, have the CO tester transmit the (3 in 5) in-band loop-down code. Verify that the
HLU-431, List 1D display returns to normal.
4
Have the CO tester send the HLU-431, List 1D (4 in 7) in-band loop-up code for five seconds. Observe that
the HLU-431, List 1D displays the “NLOC” message, which indicates that an HLU-431, List 1D loopback
is in effect.
5
Repeat Step 2. If the test passes, the problem is in the cable pair or the HRU-412. If it fails, the problem is
in the CO equipment.
6
The NREM and NLOC loopbacks can also be initiated from the front panel of the HLU-431, List 1D with
the Mode and SEL push buttons (see Section B Paragraph 14.09).
7
The HLU-431, List 1D can be looped up from the remote location (CREM) by issuing the (6 in 7) command
at the HRU-412 DS1 input port.
8
The HRU-412 can be looped up from the remote location (CLOC) by issuing the (5 in 7) command at the
HRU-412 DS1 input port.
