Section 150-388-124
Revision 01
Page 20
TABLE 4. HLU-388 A2LB TEST PROCEDURES
Step
Action
1
Send the in-band Arming and NI LPBK code 11000 into the HLU-388, List 2D, for at least five
seconds or at least four repetitions of the 16-bit ESF data link Arming code 1111 1111 0100 1000
(FF48). (Left bit arrives first.)
2
Monitor the output of the HLU-388, List 2D for the return of the pattern. Return of pattern indicates
that either the HRU-412 has looped up (if the Smart-Jack Loopback option is ENAbled) or an external
NI has looped up (if the Smart-Jack Loopback option is DISabled), and the HLU-388, List 2D and
HRU-412 units have been Armed. Verify that the HLU-388, List 2D display intermittently indicates
“Arm” and also “SMJK,” if the HRU-412 is in loopback. Also verify, if possible, that the Loopback
LED of the HRU-412 is flashing (indicating that the HRU-412 is armed), or, that the Loopback LED
lights steadily (indicating that the HRU-412 is both armed and in loopback).
3
Once armed, the HLU-388, List 2D can be looped back (NLOC in Figure 6) by sending the IOR LPBK
activation code 1101 0011 1101 0011 (D3D3) for at least five seconds. The tester observes the
following activation response:
•
Two seconds of AIS (all ones), followed by:
•
Five seconds of returning data pattern, followed by:
•
231 logic errors (including the frame bit) occur in the returned pattern (20 errors if ILR-2
was sent), followed by:
•
Normal looped data.
Note:
This error pattern will repeat every 20 seconds, as long as the IOR loopback pattern is being
sent. This same 20-second repeat scenario also applies to the Time-out Override and Query
commands. It also applies (with the appropriate number of bit errors) to the other ILR
commands.
The HiGain Line Unit is now in Logic Loopback (NLOC of Figure 6). The display on the HLU-388,
List 2D periodically shows “NLOC” (network local loop) and “Arm” (the HLU-388, List 2D is still
armed) in addition to the margin displays. The Loopback Time-out option (which is user settable to
“None,” 20, 60, or 120 minutes) determines the duration of this loopback, unless it is overridden by the
Time-out Override command or a loop-down command is sent. If the Time-out Override code 1101
0101 1101 0110 (D5D6) is received, the “activation sequence,” described in “3” above, is repeated,
and the automatic timed expiration of the loopback is inhibited. If this Time-out Override is sent, then
the only way to loop the HLU-388, List 2D down is to issue the Intelligent Repeater Loop-down (IR
LPDN) code 1001 0011 1001 0011 (9393) or to issue the NI LPDN and Disarm code 11100. The
automatic time-out timer is restored during subsequent loopback sessions.
4
Upon completion, the tester sends the IOR LPDN code 1001 0011 1001 0011 (9393) to loop down the
HLU-388, List 2D. The unit remains armed, however, as indicated by the “Arm” message on the
HLU-388, List 2D and the flashing of the HRU-412 Loopback LED.
Table continued on next page
