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2 PROCESSING OF OPERATIONS ACCORDING TO CPU MODULE OPERATION STATUS
Processing of operations by the CPU module during switch operations
Processing of operations by the CPU module is as follows according to the RUN or STOP mode.
The CPU module performs the following processing regardless of RUN or STOP status or paused status.
• Refreshing of input/output modules
• Automatic refreshing of intelligent function modules
• Self-diagnostic processing
• Device/label access service processing
• Setting of values to special relays/special registers (set timing: when END processing is executed)
For this reason, the following operations can be performed even in the STOP status or paused status:
• Monitoring of I/O or test operations by the engineering tool
• Reading/writing from external device using SLMP
• N:N Network
• MODBUS RTU slave
RUN/STOP status Processing of operations by CPU module
Processing of operations
in sequence program
External output Device memory
Other than Y Y
RUNSTOP The program is executed up to
the END instruction and then
stops.
All output points turn OFF. Latch devices are held, and
non-latch devices are cleared.
All output points turn OFF.
STOPRUN Program execution starts from
step 0.
Operation results are output
after the PLC is run for the
duration of one scan.
The states of device memories
immediately before the CPU
module entered the RUN mode
are held.
Note, however, that when
device initial values are set, the
device initial values are set.
Operation results are output
after the PLC is run for the
duration of one scan.