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Testing LTPH-UM-1109-01, Issue 1
50 January 9, 2002 H2TU-C-231 List 2
To perform the A1LB, A2LB, and the A5LB loopback test procedures:
1 Send the inband Arming and NI LPBK code 11000 to the H2TU-C-231 for at least 5 seconds.
2 Monitor the output of the H2TU-C-231 for the return of the pattern. Return of the pattern indicates one of the
following:
• The H2TU-R has looped up (if the SMJK Loopback option is enabled).
• An external NID has looped up (if the SMJK Loopback option is disabled), and the H2TU-C and
H2TU-R have been armed.
3 Verify, if possible, that the H2TU-R Loopback LED is either flashing yellow at four times per second
(indicating that the system is armed), or is a steady yellow (indicating that it is both armed and in SMJK
loopback). The H2TU-C Status LED also flashes yellow when the system is armed.
4 Once armed, the H2TU-C-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 in the order presented:
a 2 seconds of AIS (all ones pattern)
b 2 seconds of returning data pattern
c Logic errors (including the frame bit) occurring in the returned pattern comprising:
– 231 errors, if IOR LPBK (H2TU-C) was sent
– 20 errors, if ILR-2 (H2TU-R) 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 H2TU-C 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
“Setting the Loopback Time-Out Option” on page 46). 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 H2TU-C-231 down is to do one of
the following:
• Issue the Intelligent Repeater (IR) loopdown (LPDN) 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:
• If the system is to loop down but remain Armed, send the IR LPDN code.
• 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).
If the Arming code is not returned after 5 seconds, the system may be armed, but there is no
active loopback.
The Time-Out Override function is only valid for the current active loopback. The automatic
time-out timer is restored during subsequent loopback sessions.