Section 150-232-100
Revision 01
Page 58
TABLE 18. HLU-232 A2LB TEST PROCEDURES
Step
Action
1
Send into the HLU-232 List 1D the in-band ARMING and NI LPBK code 11000 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-232 List 1D for 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 that an external NI
has looped up (if the SMART-JACK LOOPBACK option is DISABLED) and that the HLU-232 List 1D and
HRU-412 units have been ARMED. Verify that the HLU-232 List 1D display intermittently indicates “ARM”
and the STATUS LED is flashing yellow at a rate of 4 times per second 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 it is illuminated steadily, indicating that it is both armed and in
loopback.
3
Once armed the HLU-232 List 1D can be looped back (NLOC in Figure 19) 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 (10 errors if ILR-1 were sent, 20
errors if ILR-2, 200 errors if ILR-20), followed by:
•
Normal looped data. Note that 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 IOR, Time-Out
Override and Query commands.
The HLU-232 List 1D is now in Logic Loopback (NLOC of Figure 19). The display on the HLU-232 List 1D
periodically shows NLOC and ARM (the HLU-232 List 1D is still armed) in addition to the margin displays
and the STATUS LED is illuminated a steady yellow. 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-232 List 1D down is to issue the IR LPDN (loop-down) 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 IR LPDN code 1001 0011 1001 0011 (9393) to loop-down the HLU-
232 List 1D. The unit remains armed however, as indicated by the ARM message and flashing yellow
STATUS LED on the HLU-232 List 1D and the flashing of the HRU-412 LOOPBACK LED.
Table continued on next page
