A-169
Appendices
CJ2 CPU Unit Software User’s Manual
A-5 Operation for Power Interruptions
App
A-5-2 Instruction Execution for Power Interruptions
Note A530 is normally cleared when power is turned OFF. To prevent this, the IOM Hold Bit (A500.12) must be
turned ON and the PLC Setup must be set to maintain the setting of the IOM Hold Bit at Startup, or the fol-
lowing type of instruction must be included at the beginning of the program to set A530 to A5A5 Hex.
3 Disable the Power OFF Interrupt Task in the PLC Setup.
With the above procedure, all instructions between DI(693) and EI(694) (or END) will be com-
pleted
*1
before the Power OFF Interrupt is executed even if the power interruption occurs while
executing the instructions between DI(693) and EI(694).
*1 The protected instructions can be completed only when the time required to complete execution is less than or
equal to the processing time after power interruption detection (10 ms − power interruption detection delay
time). If the instructions is not completed within this time, they will be interrupted and the above processing will
be performed.
Note 1 The processing time after a power interruption is detected is 1 ms when a CJ1W-PD022 is mounted.
2 If the Power OFF Interrupt Task is not disabled in the PLC Setup, the Power OFF Interrupt Task will be exe-
cuted, and the CPU Unit will be reset without executing the protected instructions as soon as the power
interruption is detected.
3 If a power interrupt is detected while DI(693) is being executed, the CPU Unit will be reset without execut-
ing the protected instructions.
If A530 (Power Interrupt Disabled Area Setting) is set to any value other than A5A5 hex to enable mask-
ing power interruption processing, power interrupt processing will be started after completing execution
of the current instruction.
Additional Information
Interrupt processing is performed according to the contents of A530 and the PLC Setup as
shown below.
Power interrupt process-
ing
A530 (Power Interrupt Disabled Area Setting)
A5A5 hex (enable masking power
interrupt processing)
Other (disable masking power inter-
rupt processing)
Power OFF
Interrupt Task
(PLC Setup)
Disabled
All instructions between DI(693)
and EI(694) are executed and the
CPU Unit is reset.
Execution of the current instruction
is completed and the CPU Unit is
reset.
Enabled
Execution of the current instruction is completed, the Power OFF Interrupt
Task is executed, and the CPU Unit is reset.
First Cycle Flag
Set A530 to A5A5 Hex at the beginning
of the program to enable disabling
power interruption processing.
MOV
#A5A5
A530
A200.11
CPU reset signal
Stopped
Instructions between
DI(693) and EI(694)
are executed.
DI(693)
EI(694)
Program execution
status
Power OFF
detected signal
85% of rated voltage
(PD025: 80%,
PD022: 90%)
Cyclic tasks or interrupt tasks
not associated with power OFF
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 Detection
Delay Time: 0 to 10 ms
(set in PLC Setup)
Power OFF detection time:
AC: 10 to 25 ms
PD025: 2 to 5 ms
PD022: 2 to 10 ms
(Power OFF
undetermined)
Power OFF confirmed
Operation always stopped
at this point regardless.
Power OFF detected
Holding time for 5 V internal power
supply after power OFF detection:
Always 10 ms (PD022: 1 ms)
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