2.2 What is a Structured Sequence Program?
2-3
2
STRUCTURED DESIGN OF
SEQUENCE PROGRAMS
2.2 What is a 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
Control content in
a programmable controller CPU
Calls Process A
Calls Process A
Calls Process A
DIV
MUL
DIV
MUL
DIV
DIV
MUL
MUL
Process A
Structured
program
Divided
Divided
Control 1
Control a
Structured
program
Control b
Control c
Control d
Control 2
A process that can be divided into components
Control
content
in a
programmable
controller
CPU
Divided
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