Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
8.3 CM4 COMMON MODULE DIAGNOSTICS
This section contains information which will help the user diagnose certain T1 related problems, and
describes the severity and frequency of trapped counter increments. Both the CM4 and DACS module
are identical with the error detection performance registers described. These registers are directly read
from the T1 Transceiver Framer chips and are stored in memory. This section also provides a brief
description of the possible Sequence of Events, which are stored in the CM4. There are up to 40
events which can be stored in the buffer.
In Table 8-1 below, the Counter Name column includes the designation of the counter when read with
NMS or with a terminal emulation program using SCL. The Update Rate column describes how a
given counter is incremented. The Severity column classifies the relative importance of given condition.
Table 8-1. CM4 Diagnostic Counters
Counter Name (NMS or SCL) Update Rate / Method Severity Effect on System Function & Notes
Currently Received Unframed All Ones
NMS: Curr Unframed All Ones Cnt
SCL:
CRBL
Curr
ent counter contains
result for previous 1s interval.
During each second CM4
checks blue alar
m* every 2m
s
- if it is present, the counter
will increase by one.
*E1 -
Unframed All Ones
Major When Unframed All Ones
signal is active, pay
load
traffic is over-written by
alarm and several other
alarms become active.
Counter reports received Alarm
Indication Signal (“
All-Ones”).
AIS is a DS1 signal containing
only 1’s. This is specifically
generated by equipment
external to MUX (such as
SONET) and typically denotes
trouble with communication
links between nodes.
Currently Received Remote Alarm
NM
S: Curr Remote Alarm Indication
Cnt
SCL:
CRYEL
Current counter contains
result for previous 1s interval.
During each second CM4
checks yellow a
larm
* every
2ms - if it is present, the
counter will increase by one.
*E1 - Remote Alarm
Minor When Yellow Alarm signal
is active, F
DL tr
affic is
over-written by alarm.
Counter reports received
Yellow Alarm. Yellow Alarm
is a message carried by the
overhead of T1. This is
specifically generated by
equipment external to MUX
and typically denote trouble
with communication links.
Unless forced, MUX does not
generate Yellow Alarm, but
passes it on.
Currently Received Carrier Losses
NMS: Curr Receive Carrier Loss Cnt
SCL:
CRCL
Current counter contains
result for previous 1s interval.
During each second CM4
checks presence of
carrier
every 2
ms - if carrier is lost,
the counter will increase by
one.
Major When Loss of Carrier
exists, payload traffic is
interrupted.
Counter r
eports Loss of Carrier
at the Common Module. Loss
of Carrier is caused by low
received signal power level or
low 1’s density. Typically, this
denotes missing T1 signal at
the multiplexer port. During
Loss of Carrier condition, the
content of other counters may
be not valid. Due to AGC
action of framer input, Carrier
Alarm may clear after initial
indication even if Loss
condition continues.
M-DACS-T1 RFL Electronics Inc.
October 25, 2004 8-11 (973) 334-3100
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