Section 150-611-100
Revision 02
Page 15
TABLE 4. HLU-611 TEST PROCEDURES FOR A1LB OPTION
Step
Action
1
Send into the HLU the inband ARMING and NIU (Network Interface Hit) LPBK code 11000 for at least
five seconds, or at least four repetitions of the 16 bit ESF Data Link ARMING code 0001 0010 1111
1111.
2
Monitor the output of the HLU-611 for the return of the pattern. Return of pattern indicates that either
the HRU has looped-up (if the SMART-JACK LOOPBACK option is ENABLED) or that an external NIU
has looped up (if the SMART-JACK LOOPBACK option is DISABLED) and that the HLU and HRU units
have been ARMED. Verify that the HLU display intermittently indicates “ARM” and also “SMJK” if the
HRU is in loopback. Also verify, if possible, that the LOOPBACK LED of the HRU-612 is flashing,
indicating that the HRU is armed or that it is on solid, indicating that it is both armed and in loopback.
3
Once armed, the HLU can be looped back (NLOC in Figure 5) by sending IOR (Intelligent Office
Repeater) LPBK activation code 1101 0011 1101 0011 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 (20 errors if ILR-2
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 the different bit error signatures generated by the ILR, Time-Out
Override and Query commands. Only 230 bit errors may be detected if the test set does not
include frame errors in its bit error count.
The HiGain-2 Line Hit is now in Logic Loopback (NLOC of Figure 5). The display on the HLU-611
periodically shows NLOC (network local loop) and ARM (the HLU 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 is received, the
activation response sequence described 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 down is to
issue the IR (Intelligent Repeater) LPDN (loopdown) code 1001 0011 1001 0011 or to issue the NIU
(Network Interface Hit) LPDN and Disarm code 11100. The automatic time-out timer is restored during
subsequent loopback sessions. The loopback time out timer is reset to 20, 60 or 120 minutes when any
of the loopback commands, except Time Out Override, are sent.
4
Upon completion, the tester sends IOR LPDN code 1001 0011 1001 0011 to loop-down the HiGain-2
Line Hit. The unit remains armed however, as indicated by the ARM message on the HLU-611 and the
flashing of the HRU-612’s LOOPBACK LED.
Table continued on next page
