Section 150-431-114
Release 01
Page 41
TABLE 12. 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-412 loopback is in effect (see Figure 15).
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 C Paragraph 19.10).
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.
9
Doubler number 1 can engage loopback from the remote location (CDU1) by issuing the (4 in 6) loopback
command at the HRU-412 DS1 input port.
10
Doubler number 1 can engage loopback from the local location (NDU1) by issuing the (2 in 6) loopback
command at the HLU-431, List 1D DS1 input port.
11
Doubler number 2 can engage loopback from the remote location (CDU2) by issuing the (5 in 6) loopback
command at the HRU-412 DS1 input port.
12
Doubler number 2 can engage loopback from the local location (NDU2) by issuing the (3 in 6) loopback
command at the HLU-431, List 1D DS1 input port.
