
150-231-184-05, Revision 05
Troubleshooting
HLU-231 List 8D
October 25, 1999
41
Alarm Option for DLC Feed
To improve HiGain compatibility with the switch-to-protect features used in DLC feeder applications, the
HLU-231 has an Alarm Pattern Option (ALMP) that allows you to select either an AIS or LOS T1 output payload
for the following alarms:
•
LOSW on any loop
•
T1 LOS.
Retiring System Alarms
To retire a system alarm, press the SEL button and execute an Alarm Cut Off (ACO). An ACO turns the alarm off
and replaces the
ALRM
message with an
ACO
message. The second part of the
ALRM
message, which defines the
cause of the alarm, remains. Both parts of the message remain until the alarm condition clears or another higher
priority alarm occurs.
Self Test
The Self Test mode that occurs when both HDSL loops are not in sync has been enhanced to include the input
DS1 transceiver chip. The Self Test procedure can cause the all ones pattern, which is normally transmitted from
the HLU-231 during these out-of-sync intervals, to exhibit occasional BPVs.
L
OOPBACK
O
PERATION
HiGain has a fixed A5LB Addressable Repeater Loopback (
) for analyzing circuit functionality. The
loopback signal is transmitted and returned to the sending device for comparison. This allows you to verify the
integrity of the HDSL channels to the HLU, the HLU DSX-1 interface, and the DS1 channels to the customer.
Loopback commands are located in
and can be initiated by:
•
Selecting the loopback type using the MODE and SEL buttons on the HLU (or the Manual Loopback button
on the HRU).
•
Selecting the loopback type from the Maintenance Terminal Main Menu when connected to the craft port of
the HLU or HRU.
•
Entering the loopback code into the test equipment connected to the HLU or HRU.
Figure 27.
Loopback Summary