I/O Processing Method; Refresh Method - Mitsubishi Electric A800 Programming Manual

3.6

I/O processing method

The control method is a refresh method.
3.6.1

Refresh method

The refresh method stores changes in the control input terminals to the CPU input data memory in batch before every scan is
executed and uses the data stored in this input data memory for operation execution.
Program operation results of the output (Y) are output to the output data memory every time, and contents stored in the output
data memory are output in batch from the control output terminals after the END instruction is executed.
CPU
(Central Processing Unit)
X0
Y22
• Input refresh
Input information is read 1) in batch from the PLC function area and stored in the input data memory (X) before executing
step 0.
• Output refresh
Output information 2) stored in the output data memory (Y) is output in batch to the PLC function area before executing
step 0.
• When executing a contact instruction for the input
Input information is read 3) from the input data memory (X) to execute a sequence program.
• When executing a contact instruction for the output
Output information is read 4) from the output data memory (Y) to execute a sequence program.
• When executing an OUT instruction for the output
Operation result of the sequence program 5) is stored in the output data memory (Y).
PLC function area
3)
Input (X) data
memory
4)
Output (Y)
Y20 5) data memory

I/O processing method

At input refresh
Control input
terminal
1)
At output refresh
Control output
terminal
2)
Sequence program
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