Section 150-319-124
Revision 03
Page 21
TABLE 4. HLU-319 A2LB TEST PROCEDURES
Step
Action
1
Send the in-band Arming and NI LPBK code 11000 into the HLU-319, 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-319, 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-319, List 2D and HRU-412 units have been Armed. Verify that the HLU-319,
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-319, 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-
319, List 2D periodically shows “NLOC” (network local loop) and “Arm” (the HLU-319, 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-
319, 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-319, List 2D. The unit remains armed, however, as indicated by the “Arm”
message on the HLU-319, List 2D and the flashing of the HRU-412 Loopback LED.
Table continued on next page
