Specifications

December 2008 Page 7–7
Chapter 7. Maintenance Module
7
chassis). This means that a local user cannot log
on until the remote user logs off.
SF SYNC DISABLED – This green LED, when
lit, indicates that this is the chassis in a loop
(usually the master) that has the Superframe
synchronization disabled. A Superframe is made
up of 24 consecutive frames. All looped systems
must have one chassis with the SF Sync disabled.
UNLOCKED – This red LED, when lit, indicates
that the Maintenance Module (i.e., the chassis) is
unlocked. If the Maintenance Module, while
unlocked, loses communication with another
module, it assumes the other module has been
pulled and does not issue an alarm. unlocked,
loses communication with another module, it
assumes the other module has been pulled and
does not issue an alarm.
LOCKED – This green LED, when lit, indicates
that the Maintenance Module (i.e., the chassis) is
locked. If the Maintenance Module, while locked,
loses communication with another module, it
issues a minor alarm.
FLIPPED – This red LED, when lit, indicates that
the chassis has flipped its channels over to the
alternate path (for systems with APM).
ARMED – This green LED, when lit, indicates
that the system is armed and ready to detect
failures for APM (for systems with APM).
RECEIVE — This green LED, when lit, indicates
that the module is receiving a PLOW call. This
means either that the person at another chassis in
the loop (with its PLOW also enabled) wants you
to pick up your phone or that the alert relay has
been activated.
SEND — This green LED, when lit, indicates that
the module is sending a PLOW call. It lights up
whenever you push the signaling button to alert
the person at another chassis in the loop (with its
PLOW also enabled) that you are trying to call via
the handset interface.
7.4.2 Status Indicators (MV4, MV5)
The Maintenance Module has a total of 17 LEDs,
nine on the main board and eight on the auxiliary
board (see Fig. 7-5 and 7-6).
The green/red status LED shows the module’s
status, with green indicating normal operation and
red indicating a failure. The status LED turns red
if the module:
1) Loses the synchronizing signals from the
Framer Module.
2) Detects a NOVRAM error not resulting
from a signaling map failure.
3) Detects a signaling map failure due to a
NOVRAM error or a DX chip error.
4) Detects an I/O chip error on the main
board.
Also, whenever the status LED turns red, the
module issues a system alarm, which is sent to all
modules in the chassis.
The other eight LEDs on the main board are in
four sets of two LEDs. The upper two LEDs,
labeled TX DATA and RX DATA, are lit to
indicate when the module is transmitting (TX) or
receiving (RX) data via the RS-232. The middle
four LEDs report the module’s synchronization
status. These four LEDs indicate, when lit, that the
direction of timing is “east” (1-1), “west” (1-2),
“north” (2-1) or “south” (2-2). The lowest two
LEDs indicate, when lit, that the module is a
master, synchronizing on its own internal clock,
and, or that the module is a slave, synchronizing to
a received T1 (or E1) signal.
The LEDs on the module’s auxiliary board are
shown in Fig. 7-6. These eight LEDs, beginning at
the top left, are as follows:
SWTEST – This red LED, when lit, indicates a
user has remotely logged onto the module (i.e., the
chassis). This means that a local user cannot log
on until the remote user logs off.
PLOW BREAK – This green LED, when lit,
indicates that the PLOW circuit passes through
and receives “party line order wire” (PLOW)
voice signals. When the LED is out, there is a
“break” in the PLOW, and the voice signals do not
pass through.
UNLOCKED – This red LED, when lit, indicates
that the Maintenance Module (i.e., the chassis) is
unlocked. If the Maintenance Module, while
unlocked, loses communication with another