Omron CP1L CPU UNIT - 03-2009, Operation Manual

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Computing the Cycle Time Section 2-7
2-7 Computing the Cycle Time
2-7-1 CPU Unit Operation Flowchart
The CPU Unit processes data in repeating cycles from the overseeing pro-
cessing up to peripheral servicing as shown in the following diagram.
NO
YES
Power ON
Checks Unit connection status.
Checks hardware and user
program memory.
Executes user program (i.e.,
executes READY cyclic tasks).
Waits until the set cycle time
has elapsed.
Calculates cycle time.
Sets error flags.
Performs I/O refreshing.
Services peripheral devices.
Peripheral
servicing
I/O
refreshing
Cycle time
calculation
Program
execution
Overseeing
processing
PLC
cycle
time
Startup
initialization
Check OK?
ERR/ALM
indicator ON or
flashing?
End of program?
Flashing
(nonfatal error)
ON (fatal error)
Error
Normal