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Explanations of PLC Setup Settings Section 7-2
Watch Cycle Time If the cycle time exceeds the watch (maximum) cycle time setting, the Cycle
Time Too Long Flag (A40108) will be turned ON and PLC operation will be
stopped. This setting must be changed if the normal cycle time exceeds the
default watch cycle time setting of 1 s.
Note The watch cycle time setting cannot be changed while the CPU Unit is in RUN
or MONITOR mode.
Note The default value for the watch cycle time is 1 s (1,000 ms).
Fixed Peripheral Servicing
Time
This setting determines whether the peripheral servicing for the following pro-
cesses is performed with the default settings (4% of the cycle time) or all
together in a fixed servicing time.
Exchange data with Special I/O Units when necessary
Exchange data with CPU Bus Units when necessary
Exchange data with peripheral port
Exchange data with serial communications ports
Service file access operations (Memory Card)
Peripheral servicing is performed at the end of the cycle, just after I/O refresh-
ing.
Watch
Time
Watch Cycle
Time
Watch Cycle
Time
Watch Cycle
Time
Actual Cycle
Time
Actual Cycle
Time
Actual Cycle
Time
OVER
Cycle Time
Too Long Flag
A40108
CPU Unit operation is
stopped.
↓
Initialization
Power ON
Common processes
Program
execution
(Tasks
executed in
order)
I/O refreshing
Peripheral servicing
Cycle
time
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