Chapter 2 Structured Design Of Sequence Programs; Hierarchical Sequence Program - Mitsubishi Electric MELSEC Q Series Programming Manual

2
STRUCTURED DESIGN OF SEQUENCE
PROGRAMS
2.1

Hierarchical Sequence Program

The hierarchy is to create a sequence program by dividing control functions performed in a programmable controller CPU into
a number of levels.
In higher levels, the processing order and timing in a fixed range is controlled. With each move from a higher level to a lower
level, control content and processes are progressively subdivided within a fixed range, and specific processes are described
in lower levels.
In the Structured project, hierarchical sequence programs are created with the configuration that states the highest level as
the project, followed by program files, tasks, and POUs (abbreviation for Program Organization Units).
Project
Program file (Operation preparation)
Task (Initialization)
Program file (Station A)
Task (Station A control)
Program file (Station B)
Task (Station B control)
Task (Indicator control)
Initial process
Lamp test
Conveyor drive A
Data process A
Conveyor drive B
Data process B
Indicator output
POUs
Initial process
Lamp test
Conveyor drive A
Conveyor drive B
Data process A
Data process B
Indicator output
2 STRUCTURED DESIGN OF SEQUENCE PROGRAMS
2.1 Hierarchical Sequence Program
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