Section 150-231-134
Revision 01
Page 16
12. TEST PROCEDURES
12.01
Tables 4 through 9 provide step by step test
procedures for the HLU-231 unit as a function
of the loopback option selected. These procedures
allow verification of the integrity of the HDSL channels
at every module location as well as the DS1 channels
to the customer and the local DSX-1 interface.
12.02
The HLU 4 character front panel display has
many useful system diagnostic messages.
They are listed in Table 10. This display turns on
when power is initially applied to the 231. In order to
conserve power, it only remains on for five minutes if
neither the MODE nor SEL buttons are pressed. The
use of either button restarts the 5 minute power-
control timer.
12.03
If trouble is encountered on the DSX-1
interface, verify that the unit is making a
positive connection with the mounting assembly’s
connector. Also, verify that the pre-equalizer is
properly set. All installations should be set to the
largest value that does not exceed the distance from
the DSX-1 to the shelf
12.04
The transmit and receive T-1 DSX-1 ports
have splitting access and bridging miniature
210-series jacks as shown in Figure 5. Connecting
one cable between the two BRG jacks and another
between the two SPAN jacks splits the XMT and RCV
and creates metallic loopbacks towards both the
DSX-1 and the HLU. If plugs are inserted in both
SPAN jacks. The BRG jacks can be used to send &
receive test patterns towards the DSX-1.
TABLE 4. TEST PROCEDURES FOR GNLB OPTION
Step
Action
1
Have the C.O. tester send the HRU (3 in 7) in-band loop-up for 5 seconds. Observe that the HLU
displays the “NREM” message indicating an HRU loopback is in effect (see Figure 4).
2
Have the C.O. tester transmit a T1 test signal into the HLU and verify that the returned (looped-
back) signal is error free.
3
If the above test fails, have the C.O. tester transmit the (3 in 5) in-band loop-down code. Verify
that the HLU display returns to normal.
4
Have the C.O. tester send the HLU (4 in 7) in-band loop-up for 5 seconds. Observe that the HLU
displays the “NLOC” message indicating an HLU loopback is in effect.
5
Repeat step “2”. If the test passes, the problem is in the cable pair or the HRU. If it fails, the
problem is in the C.O. equipment
6
The NREM and NLOC loopbacks can also be initiated from the front panel of the HLU with the
MODE and SEL pushbuttons. See Paragraph 10.9 for details.
7
The HLU can be looped-up from the remote location (CREM) by issuing the 6 in 7 command at
the HRU’s DS1 input port.
8
The HRU can be looped-up from the remote location (CLOC) by issuing the 5 in 7 command at
the HRU’s DS1 input port.
9
Doubler 1 can be looped-up from the remote location (CDU1) by issuing the 4 in 6 command at
the HRU’s DS1 input port.
10
Doubler 1 can be looped-up from the network location (NDU1) by issuing the 2 in 6 command at
the HLU’s DS1 input port.
11
Doubler 2 can be looped-up from the remote location (CDU2) by issuing the 5 in 6 command at
the HRU’s DS1 input port.
12
Doubler 2 can be looped-up from the network location (NDU2) by issuing the 3 in 6 command at
the HLU’s DS1 input port.
