There are three different classes of POU’s, classified on the basis of their functionality:
쎲
Programs
쎲
Functions
쎲
Function Blocks
POU’s declared as Function Blocks can be considered as programming instructions in their
own right and they can be used as such in every module of your programs.
The final program is compiled from the POU’s that you define as programs. This process is han
-
dled by the task management, in the Task Pool. Program POU’s are put together in groups
referred to as “Tasks”.
Tasks
Most PLC programs consist of areas of code which perform specific tasks.They may form part of
one large program, or be written in sub-routines, with program control instructions to select the
current routine i. e. CALL, CJ etc.
Programming Software Structure and Definition of Terms
Training Manual GX IEC Developer 3 - 3
The Program POU’s are grouped together
in tasks
In turn, all the tasks are grouped
together to form the actual PLC
program.
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