Section 150-232-100
Revision 01
Page 8
4. ALARMS
4.01 The normally open alarm contacts available across pins 12 and 14 (Figure 3) comprise the HLU-232’s Minor
Alarm output and are available at the 220 shelf back plane across pins 20 and 21 respectively (Figure 5). These
alarm contacts close for any of the following alarm conditions, and the alarm type is shown on the HLU-232 List 1D
front panel display. If multiple alarm conditions exist, only the highest priority alarm type is shown. The following
alarms are listed from highest to lowest priority.
TYPE
REASON
ALRM LOSW:
Either HDSL loop loses sync.
ALRM LLOS:
Loss of the HLU DS1 input signal.
ALRM RLOS:
Loss of HRU DS1 input signal.
ALRM TLOS:
The DS1 input to the HRU, whose TLOS switch
option has been enabled, is not present (LOS).
ALRM H1(2)ES:
HDSL Loop 1 or Loop 2 has exceeded the 24-
hour user-selected Errored-Seconds CRC
threshold.
ALRM DS1:
The total number of bipolar violations (BPV) at
the HLU or HRU DS1 inputs have exceeded the
24-hour user-selected threshold.
ALRM MAL1(2):
The margin on HDSL Loop 1 or Loop 2 has
dropped below the minimum threshold value set
by the ASCII terminal MARGIN ALARM THRES
option; as described in Section 8.
The following alarms can only occur if the system is configured for Protection Switching capability:
TYPE
REASON
ALRM PROT
The system is operating on the Protection circuit
due to a failure of the Primary circuit
ALRM HBER
The user selectable HDSL bit error rate has been
exceeded
ALRM PROR
The HRU is not responding to HLU Protection
commands
