What Is A Hierarchical Sequence Program - Mitsubishi Electric MELSEC Q Series Structured Programming Manual

2.1

What is a 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
2.1 What is a Hierarchical Sequence Program?
2-2
Program file (Operation preparation)
Task (Initialization)
Program file (Station A)
Task (Station A control)
Program file (Station B)
Task (Station B control)
Conveyor drive B
Task (Indicator control)
Initial process
Lamp test
Conveyor drive A
Data process A
Data process B
Indicator output
POUs
Initial process
Lamp test
Conveyor drive A
Conveyor drive B
Data process A
Data process B
Indicator output