5-1-2
Power OFF Operation
WARNING
The NX-series Controller continues normal operation for a specific period of time even
when a momentary power interruption occurs. The Controller may therefore receive
incorrect signals from external devices that are af
fected by the momentary power in-
terruption.
T
ake suitable actions, such as external fail-safe measures and interlock conditions, to
monitor the power supply voltage of the external devices as required.
A power OFF status is detected when the Unit power supply drops to the following voltage or lower or
when the following time has elapsed due to a momentary power interruption.
Momentary power inter-
ruption voltage
Power OFF detection time
20.4 VDC or less
2 ms min.
*1
to 8 ms max.
*1. A power OFF status may be detected when a momentary power interruption of 2 ms or less occurs consec-
utively.
Operation at Power OFF
Execution of the user program is ended if a power interruption exceeds the time shown in the table
below. The processing after power interruption confirmation (described below) is performed, and then
the system (i.e., CPU Unit) stops.
System reset
Voltage drop
Executing user program
Processing after power interruption is confirmed.
DC: 20.4 V max.
Power interruption confirmed.
System stops.
(CPU Unit stops.)
Power OFF detection time
2 to 8 ms
As shown in the following figure, the system (i.e. CPU Unit) will stop even if the voltage recovers after
the power interruption detection time.
Voltage drop
DC: 20.4 V max.
Power
interruption
confirmed.
System stops.
(CPU Unit stops.)
Voltage
recovery
System reset Executing user program
Power OFF detection time
2 to 8 ms
Processing after power interruption is confirmed.
After stopping, the system will restart if the power supply remains recovery.
The table below defines the time that is used in the above two figures.
5 Installation and Wiring
5-5
NX-series NX1P2 CPU Unit Hardware User’s Manual (W578)
5-1 Processing at Power ON and Power OFF
5
5-1-2 Power OFF Operation
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