Disconnecting power from the SNC
Disconnect power from the SNC by removing the gray 2-
pin terminal block from the 24 V~ power terminal port on
the SNC.
When you disconnect or lose supply power from the
SNC, the SNC becomes non-operational when the power
management settings expire. The blue HEARTBEAT LED
remains on, and the super capacitor continues to power
the SNC for approximately 30 seconds so that volatile data
can be backed up in nonvolatile memory. The HEARTBEAT
LED goes off when the data backup completes.
Important: The behavior of the super capacitor is
different from backup batteries that supervisory
controllers have used in the past. For example, the
capacitor requires time to recharge after each power
cycle. The unit is not designed for frequent power
cycles over a short period of time, such as three or
four power cycles in one hour. In this scenario, the
capacitor can deplete enough so that it no longer
functions. A fully depleted capacitor can take up to
90 minutes to recharge after the SNC is plugged into
its power source.
Rotary switch dials
The SNC has 3 rotary switch dials labeled Controller
Number for setting the controller number which can be
numbered from 000 to 999. The switches are shipped
from the factory set to 000. You can use them to set a
decimal number from 000 to 999 as a unique identifier for
each SNC.
Setting the controller number
About this task:
The controller number is set using three rotary switches
and may be numbered from 000 to 999. The numbers
are ordered from left to right, most significant bit (MSB)
to least significant bit (LSB). In the following image, the
switches are set to 1 2 3. If you change the controller
number, refresh the SMP Hardware tab to see the
change.
Figure 12: Rotary switch controller number
Troubleshooting
LED status indicators
LEDs on the front panel of the SNC indicate its functional
state. For a comprehensive list of LED functional
information, see Table 10.
LED test sequence at startup
During startup, the SNC automatically initiates a self-test
to verify correct operation of the unit. When you connect
supply power, the following LED lighting sequence occurs:
• The HEARTBEAT LED flashes blue/purple when the SNC
starts.
• The FAULT LED is solid red for approximately 30
seconds, then turns off.
• The USB-1|2 LED flashes green when a supported
device is connected to either of the USB ports. The
LED turns solid red when an unsupported device is
connected. The LED is off if no device is connected.
SNC LED indication table
Table 10 describes each LED on the device. The normal states are in bold. A flicker has a fast blink rate faster than one
second and a flash has a much slower blink rate of one second.
F4-SNC Installation Guide18
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