Issue 1, Section 150-231-164
Revision 04
Page 21
TABLE 7. HLU-231 A5LB TEST PROCEDURES
Step
Action
1
Send into the HLU-231 List 6D the in-band ARMING and NI (Network Interface) 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 arrive first)
2
Monitor the output of the HLU-231 List 6D 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 that an external NI has looped up (if the SMART-JACK LOOPBACK option is
DISABLED) and that the HLU-231 List 6D and HRU-412 units have been ARMED. Verify that
the HLU-231 List 6D 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 it lights steadily, indicating that it is both armed
and in loopback.
3
Once armed the HLU-231 List 6D can be looped back (NLOC in Figure 5) by sending IOR
(Intelligent Office Repeater) 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 bits) occur in the returned pattern (10 errors if ILR-1
were sent), 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 ILR, Time-Out Override and Query commands.)
The HiGain Line Unit is now in Logic Loopback (NLOC of Figure 5). The display on the HLU-
231 List 6D periodically shows NLOC and ARM (the HLU-231 List 6D 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-231 down is to issue the IR (Intelligent
Repeater) LPDN (loopdown) code 1001 0011 1001 0011 (9393) or to issue the NI (Network
Interface) LPDN and Disarm code 11100. The automatic time-out timer is restored during
subsequent loopback sessions.
4
Upon completion, the tester sends IOR LPDN code 1001 0011 1001 0011 (9393) to loop-down
the HLU-231 List 6D. The unit remains armed however, as indicated by the ARM message on
the HLU-231 List 6D and the flashing of the HRU-412 LOOPBACK LED.
Table continued on next page
