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7 PROGRAMMING WHEN EXECUTING THE MASTER FUNCTION

This chapter explains programming when the master function is executed.

7.1 Precautions on Programming

This section explains the precautions when creating a program.

(1) Observe the following to perform input/output communication with a slave node.

• Place the I/O communication read processing program at the beginning of a

sequence program.

• Place the I/O communication write processing program at the end of a sequence

program.

Refresh processing request, I/O communication read processing

I/O communication write processing

•
•
•
•
•
•

(2) Perform the reading of reception data and the writing of transmission data only

when there is no error in the module and the module is in the ready status.

Program for communication

X0F

Module error

Module ready

(3) Create a program that detects the communication status of each node and

performs interlock. Also, create a program that handles errors when they occur.

Node No. 0 error handling program

X0F

Module error

Module ready

FROM

H1BC

K4MO

Slave station communication status

Node No. 1 error handling program

Node No. 0 normal processing program

Node No. 1 normal processing program