Description Of Operation - Omron CJ2 CPU - REV 10-2010 User Manual

85% of the rated voltage or less (DC power supply: 80% or less for PD025, 90% or less for PD022)
0
0 to 10 ms
(PD025/PD022:
0 to 2 ms)
Momentary power
interruption not detected
and operation continues.
Power supply
voltage
Power supply
voltage
Power supply
voltage
Note The above timing chart shows an example when the power OFF detection delay time is set to 0 ms.
Power OFF Timing Chart
The following timing chart shows the CPU Unit power OFF operation in more detail.
85% of rated voltage
(PD025: 80%,
PD022: 90%)
Power OFF
detected signal
Cyclic tasks or interrupt tasks not associated
Program execution
with power OFF
status
CPU reset signal
Power OFF Detec-
tion Time:
Power OFF Detec-
tion Delay Time:
Power Holding Time: The maximum amount of time (fixed at 10 ms) that 5 V will be held internally after power

Description of Operation

• Power OFF will be detected if the 100 to 240-VDC power supply falls below 85% (80% for CJ1W-
PD025 DC Power Supply Units or 90% for CJ1W-PD022 DC Power Supply Units) of the minimum
rated voltage for the power OFF detection time (somewhere between 10 to 25 ms for AC Power Sup-
ply Units, somewhere between 2 to 5 ms for CJ1W-PD025 DC Power Supply Units, and somewhere
between 2 to 10 ms for CJ1W-PD022 DC Power Supply Units).
CJ2 CPU Unit Software User's Manual
10 ms
10 to 25 ms
(PD025: 2 to 5 ms,
PD022: 2 to 10 ms)
Operation will continue or stop
depending on whether or not a
momentary power interruption
is detected.
Holding time for 5 V internal power
supply after power OFF detection:
Always 10 ms (PD022: 1 ms)
Power OFF detected Power OFF confirmed
Power OFF detection time:
Power OFF Detection
AC: 10 to 25 ms
Delay Time: 0 to 10 ms
PD025: 2 to 5 ms
(set in PLC Setup)
PD022: 2 to 10 ms
(Power OFF undetermined)
The time it takes to detect power OFF after the power supply falls below 85% (80% for
CJ1W-PD025 DC Power Supply Units or 90% for CJ1W-PD022 DC Power Supply Units)
of the minimum rated voltage.
The delay time after power OFF is detected until it is confirmed. This can be set in the PLC
Setup within a range from 0 to 10 ms.
If an unstable power supply is causing power interruptions, set a longer Power OFF Detec-
tion Delay Time (10 ms max.) in the PLC Setup. The CJ1W-PD022 Power Supply Units
only support a holding time of 1 ms, however, so this setting is not possible.
shuts OFF. The time that it takes for the power OFF interrupt task to execute must not
exceed 10 ms minus the Power OFF Detection Delay Time (processing time after power
OFF is confirmed). The power OFF interrupt task will be ended even if it has not been
completely executed the moment this time expires. The CJ1W-PD022 Power Supply Units
only support a holding time of 1 ms, however, so this setting is not possible.
25 ms
Time
25 ms
(PD025: 5 ms, PD022: 10 ms)
Momentary power interruption
detected and operation stops.
Operation always stopped
at this point regardless.
Processing time after power OFF is confirmed:
10 ms minus Power OFF Detection Delay Time
(PD022: 1 ms minus Power OFF Detection
Delay Time)
Note: The interrupt task execution time must be
less than or equal to processing time after
power OFF is confirmed.
Power OFF
Stopped
interrupt task
Appendices
A-169