
150-231-184-05, Revision 05
Troubleshooting
HLU-231 List 8D
October 25, 1999
47
To perform the A5LB test procedures:
1
Send the inband Arming and NI LPBK code 11000 to the HLU-231 for at least 5 seconds.
2
Monitor the output of the HLU-231 for the return of the pattern. Return of the pattern indicates one of the
following:
a
The HRU has looped up (if the SMJK Loopback option is Enabled).
b
An external NI has looped up (if the SMJK Loopback option is Disabled), and the HLU and HRU have
been armed.
3
Verify, if possible, that the HRU Loopback LED is either flashing yellow at 4-second intervals (indicating
that the system is armed), or is a steady yellow (indicating that it is both armed and in SMJK loopback). The
HLU Status LED also flashes yellow when the system is armed.
4
Once armed, the HLU-231 can be looped back by sending Intelligent Office Repeater (IOR) LPBK activation
code 1101-0011-1101-0011 (D3D3) for at least 5 seconds. You should observe the following activation
response pattern:
a
2 seconds of AIS (identified by an all ones pattern)
b
2 seconds of returning data pattern
c
231 logic errors (including the frame bit) occurring in the returned pattern comprising:
–
10 errors, if ILR-1 (Doubler 1) was sent
–
200 errors, if ILR-20 (Doubler 2) was sent
–
30 errors, if ILR-3 (Doubler 3) was sent
–
40 errors, if ILR-4 (Doubler 4) was sent
–
20 errors, if ILR-2 (HRU) was sent
d
Normal looped data.
This error pattern repeats every 20 seconds as long as the IOR loopback pattern is being sent. This also applies
to ILR, Time-out Override, and Query commands.
The HLU is now in logic loopback if the IOR NLOC loopback command was sent. The Time-out Override
command or a Loopdown command can override the selection made for the loopback time-out (see
the Loopback Time-out Option” on page 43
). If the Time-out Override code 1101-0101-1101-0110 (D5D6)
is received after activating a loopback, then 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 do one of the following:
•
Issue the IR (Intelligent Repeater) LPDN (loopdown) code 1001-0011-1001-0011 (9393).
•
Issue the NI LPDN and Disarm inband code 11100 or the ESF-DL code (FF24).
5
Once the test is complete, do one of the following:
a
If the system is to loopdown but remain Armed, send the IR (Intelligent Repeater) LPDN code (universal
loopdown).
b
If all the equipment is to be looped down, disarmed and returned to normal operation, send the disarm
inband code 11100 or the ESF-DL code (FF24).
The Time-out Override function is only valid for the current active loopback. The automatic
Time-out timer is restored during subsequent loopback sessions.