Section 150-619-100
Revision 01
Page 22
12. HLU-619 A2LB TEST PROCEDURE
1. Send the in-band Arming and NI LPBK code
11000 into the HLU-619 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-619 for the return
of the pattern. Return of pattern indicates that
either the HRU-612 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-619 and HRU-
612 units have been Armed. Verify that the HLU-
619 display intermittently indicates “Arm” and
also “SMJK,” if the HRU-612 is in loopback. Also
verify, if possible, that the Loopback LED of the
HRU-612 is flashing indicating that the HRU-612
is armed, or, that the Loopback LED lights
steadily indicating that the HRU-612 is both
armed and in loopback.
3. Once armed, the HLU-619 can be looped back
(NLOC in Figure 5) by sending the IOR LPBK
activation code 1101 0011 1101 0011 (D3D3) for
at least five seconds. You can see 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 repeats 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.
4. The HiGain-2 Line Unit is now in Logic Loopback
(NLOC of Figure 5). The display on the HLU-619
periodically shows “NLOC” (network local loop)
and “Arm” (the HLU-619 is still armed) in addition
to the margin displays. The Loopback Time-out
option 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 step 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-619 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.
5. When you are done, send the IOR LPDN code
1001 0011 1001 0011 (9393) to loop down the
HLU-619. The unit remains armed, as indicated
by the “Arm” message on the HLU-619 and the
flashing of the HRU-612 Loopback LED.
6. Using the following codes, a network tester can
activate loopbacks NLOC or NREM or SMJK (if
ENAbled) (see Figure 5). A customer tester can
activate loopbacks CLOC or CREM.
