Software Structure and Definition of Terms
Software Structure and Definition of Terms
3.2
In the following section, the primary terms used within GX IEC Developer will be defined:
b POU's
b GLOBAL VARIABLES
b LOCAL VARIABLES
b USER DEFINED FUNCTIONS & FUNCTION BLOCKS
b TASK POOL
b PROGRAM EDITORS:
– Instruction List
– Ladder Diagram
– Function Block Diagram
– Sequential Function Chart
– Structured Text
– MELSEC Instruction List
3.2.1
Definition of Terms in IEC61131-3
Projects
A Project contains the programs, documentation and parameters needed for an application.
POU - Program Organisation unit
The structured programming approach replaces the former unwieldy collection of individual
instructions with a clear arrangement of the program into program modules. These modules are
referred to as Program Organisation Units (POU's), which form the basis of the new approach to
programming PLC systems.
3 - 2
Program organisation units (POU's) are
used to implement all programming tasks.
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Programming