The data protection battery slowly loses charge when 24
VAC power is removed from the NCM. If the battery
completely loses charge, the NCM real-time clock stops.
The database and code, however, are still retained. (This
is different from the NCM300 Series model, in which only
72 hours of backup was provided, after which the unit
required a download.)
Whenever an NCM is disconnected from 24 VAC power
for over 30 days, ensure that the unit has the correct date
and time. Also, keep the NCM powered long enough to
recharge the data protection battery.
Setting the End-of-Line Switch
Network and field devices at either end of the N2 Bus
must be set as network terminated devices. The
NCM
has an
EOL
switch that allows you to set the NAE as a
network terminated device. The NCM is shipped with the
EOL switch in the factory default, ON (up) position (
). Set the EOL switch to the appropriate position for each
NCM in your network. For more details, refer to the
Setting Terminations section of the
N2 Communications
Bus Technical Bulletin (LIT-636018)
.
Figure 8: FC Bus EOL Switch in the Factory Default
ON (Up) Position
Turning On the NCM
Apply 24 VAC power to the
NCM
and verify that the RUN
LED begins to flash. This indicates normal operation. If
this is a new NCM from the factory, the RUN LED
continues to flash, indicating that the unit needs to be
commissioned with WNCSETUP. Refer to the
NCM45x0-2
Network Control Module Commissioning Guide
(LIT-12011176)
for additional information on
commissioning an NCM.
Disconnecting Power from the NCM
When 24 VAC supply power to an
NCM
is disconnected
or lost, the NCM is non-operational, but the POWER LED
(
) remains On and the data protection battery
continues to power the NCM for a few minutes while
volatile data is backed up in nonvolatile memory. The
RUN LED flashes during this process. When complete,
all LEDs go Off.
Important:
Do not disconnect the battery while the unit
is shutting down, or the data being saved
may be corrupted.
Important:
The data protection battery must be installed
and charged before disconnecting the 24
VAC supply power.
Troubleshooting
LED Status Indicators
The
NCM
has nine LEDs to indicate power and network
communication status.
shows the LEDs and
describes the LED indications. For the NCM4510-2 model,
the
FC
Bus LED indicates network traffic over the N2
Bus. For the NCM4520-2 model, the LON LED indicates
network traffic over the LON Network. All the other LEDs
are the same on both models.
Figure 9: NCM LED Designations
LED Test Sequence at Startup
When you connect power to the
NCM
, it initiates a
2-second LED test to verify the operational status of its
LEDs. After this test, the operating system is loaded, the
NCM application starts, the NCM database is loaded from
flash memory (or, if not present, downloaded from the
OWS
), and NCM initialization occurs. A steady On RUN
LED indicates a fully initialized NCM. If the RUN LED
continues to blink for several minutes, verify whether the
NCM database was successfully downloaded from the
archive Operator Workstation. You can also examine the
Network Controller (NC)
Task Error Log, which may
provide useful information for diagnosing startup
problems. For details, refer to the
NCM45x0-2 Network
Control Module Commissioning Guide (LIT-12011176)
.
For more information about the other possible behaviors
of the NCM LEDs, see
8
NCM45x0-2 Series Network Control Module Installation Instructions
