Mitsubishi Electronics FR-A700, 700 Series I/O Processing Method, What is refresh system?

I/O Processing Method

3.6 I/O Processing Method

The control system is a refresh system.

3.6.1What is 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.

PLC

CPU

(Central Processing Unit)

		3)	Input (X) data	At input refresh	Control input
X0			memory	1)	terminal
		4)		At output refresh
Y22			Output (Y)		Control output
			data memory		terminal
	Y20	5)		2)

•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.

Fig 3.6 I/O Data Flows in Refresh System

SEQUENCE PROGRAMMING

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