Section 150-319-124
Revision 03
Page 18
TABLE 2. HLU-319 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-319, List 2D 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-319, List 2D 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-319, List 2D display returns to normal.
4
Have the CO tester send the HLU-319, List 2D (4 in 7) in-band loop-up code for five seconds.
Observe that the HLU-319, List 2D displays the “NLOC” message, which indicates that an HLU-
319, List 2D 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-319, List 2D
with the Mode and SEL push buttons (see Section B Paragraph 14.09).
7
The HLU-319, List 2D 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.