Structured Sequence Program - Mitsubishi Electric MELSEC Q Series Programming Manual

2.2

Structured Sequence Program

A structured program is a program created by components. Processes in lower levels of hierarchical sequence program are
divided to several components according to their processing information and functions.
In a structured program design, segmenting processes in lower levels as much as possible is recommended. Each
component is designed to have a high degree of independence for easy addition and replacement.
The following shows examples of the process that would be ideal to be structured.
• A process that is used repeatedly in a sequence program.
• A process that can be divided into components.
A process that is used repeatedly in a sequence program
Control content in
a programmable controller CPU
A process that can be divided into components
Control
content
in a
programmable
controller
CPU
2 STRUCTURED DESIGN OF SEQUENCE PROGRAMS
12
2.2 Structured Sequence Program
DIV
MUL
DIV
MUL
DIV
MUL
Structured
program
Divided
Control 1
Divided
Divided
Control 2
Control content in
a programmable controller CPU
Calls Process A
Calls Process A
Calls Process A
Process A
DIV
MUL
Control a
Control b
Control c
Control d
Structured
program