PairGain HiGain Line Unit HLU-388, Manual

Page: 53 / 68

150-388-125-01, Revision 01 Loopback Operation
HLU-388 List 2E September 15, 1998 43
The HLU is now in Logic Loopback. The Loopback Time-out option is user settable to:
• NONE (0 minutes)
• 20 minutes
• 60 minutes
• 120 minutes
These selections determine 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 4, 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-388 down
is to:
• Issue the IR (Intelligent Repeater) LPDN (loop-down) code 1001 0011 1001 0011 (9393) or
• Issue the NI LPDN and Disarm code 11100.
The automatic time-out timer is restored during subsequent loopback sessions.
5 Once the test is complete, do one of the following:
• If the system is to loopdown but remain ARMED, send the IR (Intelligent Repeater) LPDN code
(universal loopdown).
• If all the equipment is to be looped down, disarmed and returned to normal operation, send the disarm
code 11100.
Using the codes listed in Table 13 on page 44 , a network tester can activate loopbacks NLOC or NREM or SMJK
(if enabled). A customer tester can activate loopbacks CLOC or CREM. All loopbacks shown in Table 13 can also
be initiated from the HLU-388 front panel MODE and SEL buttons (see “Setting Options Through SEL and
MODE” on page 9 ).
The ARMED mode has an automatic time-out of 120 minutes but this timer is reset to 120 for any
of the following events:
•
Loopback terminates (manually or time-out),
• Query
• Alternate query
• Far end activate
• Another ARM command.