Omron SYSMAC CV Series - Power off Interruption and Restart Continuation

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The diagram and explanation below describe CPU operation when the PC is set
for restart continuation and power is interrupted and then returned after the CPU
is stopped.
Shutdown
processing
(1 ms)
Momentary power
interruption time
(default: 0 ms)
Initialization
processing
Normal
Normal
CPU stopped
Standby
Power OFF interrupt
program
Power ON interrupt program
Power restored
Execution of current instruction completed.
Execution
continues
from next
instruction.
Power
interruption
detected
Program
execution
Power hold time: 10 ms (fixed)
1, 2, 3... 1. Execution of the main program is stopped when the power interruption sig-
nal is output, and the CPU then waits for the momentary power interruption
time set in the PC Setup.
2. The power OFF interrupt program is executed when the momentary power
interruption time is exceeded. If program execution was interrupted by the
power interruption signal, the power OFF interrupt program is executed af-
ter the interrupted instruction has been completed.
3. The CPU will be stopped and all outputs turned OFF when either the power
OFF interrupt program is completed or 10 ms has passed since the power
interruption signal was output, whichever occurs first.
4. Initialization processing will be performed when power returns to the PC.
5. After initialization, the power ON interrupt program will be executed if one
has been prepared.
6. The main program will then be executed from the instruction just after the
one that was being executed when the power interruption signal was output.
Take the following precautions to ensure proper restart continuation.
1, 2, 3... 1. If 10 ms has elapsed since the power interrupt signal was received, the CPU
will be stopped even if the power OFF interrupt program is still running. Be
sure that the power OFF interrupt program is as short as possible.
Verify that the total time required for the system shutdown procedure (1 ms),
momentary power interruption time (set in the PC Setup), interrupted
instruction completion time (depends on the instruction that is interrupted),
and the power OFF interrupt program (depends on program length) does
not exceed 10 ms.
2. When program execution was interrupted by the power interruption signal,
the power OFF interrupt program is executed after the interrupted instruc-
tion is completed.
A particularly long instruction, such as SEND(192) or RECV(193), might not
be completed by the end of the 10 ms power hold time, and some data might
be lost.
3. Restart continuation will not occur when:
d) A fatal error (one stopping the CPU) occurs.
e) The power OFF interrupt program was not completed within the power
hold time (10 ms).
f) The PC memory has somehow been completely altered when power
was interrupted.
If memory is disrupted, the main program will be executed from the be-
ginning if the PC can still run when power returns.
Operation
Precautions
PC Operation Section 6-1