42
2.3 Scan Time Structure
A CPU module sequentially performs the following processing in the RUN status. Scan time is the time required for all
processing and executions to be performed.
2.3.1 Initial processing
The CPU module performs preprocessing required for program operations. The preprocessing is executed only once
when any of the operations described in the following table is performed to the CPU module. When initial processing is
completed, the CPU module is placed in the operation status set by the switch. ( Page 45, Section 2.4)
: Performed, ×: Not performed
*1 The operation indicates that the status is changed back to RUN without resetting the module after any program or
parameter was changed in the STOP status. (The switch is set from STOP to RUN (the RUN LED will flash), then back
to STOP and to RUN again.)
Note that the PLSP instruction (instruction for pulse conversion) may not be executed properly with the above
operation. This is because the previous information may not be inherited depending on the program changes.
Initial processing item
CPU module status
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Changed from STOP to
RUN
*1
The I/O module initialization ×
Boot from an SD memory card ×
PLC parameter check
Initialization of devices outside the latch range
(bit device: off, word device: 0)
×
Automatic I/O number assignment to connected modules
Intelligent function modules switch setting ×
CC-Link information setting ×
Ethernet information setting ×
Initial device value setting
Power-on or reset
Scan time
( )
( )
( )
( )
Initial processing
Refresh processing
Program operation
END processing
Page 44, Section 2.3.4
Page 43, Section 2.3.3
Page 43, Section 2.3.2
Page 42, Section 2.3.1
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