Mitsubishi Electronics 700 Series ユーザーズマニュアル

The control system is a refresh system.

In the refresh system, control input terminal changes are batch-imported into the input
data memory of the CPU before execution of each scan, and the data of this input data
memory are used as the input data for operation execution.
Each program operation result of the output (Y) is output to the output data memory,
and after the END instruction is executed, the contents of the output data memory are
batch-output from the control output terminal.

Fig 3.6 I/O Data Flows in Refresh System

• Input refresh

Before execution of step 0, input data are batch-read from the input module (1))
and stored into the input (X) data memory.

• Output refresh

Before execution of step 0, the data of the output (Y) data memory (2)) are batch-
output to the output module.

• When input contact instruction is executed

Input data are read from the input (X) data memory (3)) and the sequence
program is executed.

• When output contact instruction is executed

Output data are read from the output (Y) data memory (4)) and the sequence
program is executed.

• When output OUT instruction is executed

The operation result (5) of the sequence program is stored into the output (Y) data
memory.

CPU 

(Central Processing Unit)

1)

2)

4)

5)

Y20

Y22

X0

3)

Input (X) data 
memory

Output (Y) 
data memory

Control input 
terminal

At input refresh

Control output 
terminal

At output refresh

PLC