Omron NSJ CONTROLLERS - 03-2008 Operation Manual page 151

Power OFF Operation
Description of Operation
1,2,3...
Note
7-1-2 Instruction Execution for Power Interruptions
Note
Disabling Power Interruption Processing in the Program
120
Power Holding Time
The maximum amount of time (fixed at 2 ms) that 5 V will be held internally
after power shuts OFF. The time that it takes for the power OFF interrupt task
to execute must not exceed 2 ms. The power OFF interrupt task will be ended
even if it has not been completely executed the moment this time expires.
Power OFF will be detected if the power supply voltage falls below the power
OFF detection voltage for the power OFF detection time (2 ms for the NSJ
Controller, somewhere between 10 to 25 ms for AC Power Supply Units,
somewhere between 2 to 5 ms for the CJ1W-PD025 DC Power Supply Unit,
and somewhere between 2 to 10 ms for the CJ1W-PD022 DC Power Supply
Unit), and then the following processing will be performed.
1. If the power OFF interrupt task is disabled (default PLC Setup setting)
The CPU reset signal will turn ON and the Controller Section will be reset
immediately.
2. If the power OFF interrupt task is enabled in the PLC Setup, the CPU reset
signal will turn ON and the Controller Section will be reset after the power
OFF interrupt task has been executed (see note). Make sure that the pow-
er OFF interrupt task will finish executing within 2 ms. The 5-V internal
power supply will be maintained only for 2 ms after power OFF is detected.
The holding time for the internal 5-V power supply of CJ1W-PD022 Power
Supply Units when a power interruption occurs is 1 ms. This means that the
Power OFF Interrupt Task cannot be used.
If power is interrupted and the interruption is confirmed when the NSJ Control-
ler is operating in RUN or MONITOR mode, the instruction currently being
executed will be completed (see note 1) and the following power interruption
processing will be performed.
• If the power OFF interrupt task is disabled, the Controller Section will be
reset immediately.
• If the power OFF interrupt task is enabled, the task will be executed and
then the Controller Section will be reset immediately.
The power OFF interrupt task is enabled and disabled in the PLC Setup.
1. The current instruction can be completed only when the time required to
complete execution is less than or equal to the processing time after power
interruption detection (2 ms). If the instruction is not completed within this
time, it will be interrupted and the above processing will be performed.
2. The processing time after a power interruption is detected is 1 ms when a
CJ1W-PD022 is mounted. The above processing will thus be started 1 ms
after the power interruption occurs.
If the power OFF interrupt task is disabled, areas of the program can be pro-
tected from power interruptions so that the instructions will be executed before
the power OFF processing is performed even if the power supply is inter-
rupted. This is achieved by using the DISABLE INTERRUPTS (DI(693)) and
ENABLE INTERRUPTS (EI(694)) instructions.
The following procedure is used.
Section 7-1