Programming For Executing The Master Function; Programming Precautions - Mitsubishi Electric QJ71DN91 User Manual

7 PROGRAMMING FOR EXECUTING THE MASTER FUNCTION

7 PROGRAMMING FOR EXECUTING THE MASTER FUNCTION

7.1 Programming Precautions

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This chapter explains programming for executing the master function.
When applying the program examples introduced in this chapter to the actual system,
make sure to examine the applicability and confirm that it will not cause system control
problems.
When creating programs, pay attention to the following:
(1) To perform I/O communication with a slave node, perform the following:
• Place the I/O communication read processing program at the beginning of the
sequence program.
• Place the I/O communication write processing program at the end of the
sequence program.
Refresh processing request, I/O communication read processing
(2) Reading receive data and writing transmit data must be performed when there is
no error in the module and the module is in the ready status.
Module error Module ready
X0 X0F
3) Create a program that detects the communication status of each node and
performs interlock. Also, create an error handling program.
Module error Module ready
X0 X0F
M0
M1
M0
M1
•
•
•
•
•
•
I/O communication write processing
Program for communication
Node communication status
FROM H0
Node No. 0 error handling program
Node No. 1 error handling program
Node No. 0 normal processing program
Node No. 1 normal processing program
MELSEC-Q
H1BC K4MO K4
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