Mitsubishi Electric FX Series - Software Structure and Definition of Terms; Definition of Terms in IEC61131-3

3.2 Software Structure and Definition of Terms
In the following section, the primary terms used within GX IEC Developer will be defined:
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POU’s
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GLOBAL VARIABLES
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LOCAL VARIABLES
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USER DEFINED FUNCTIONS & FUNCTION BLOCKS
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TASK POOL
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PROGRAM EDITORS:
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Instruction List
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Ladder Diagram
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Function Block Diagram
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Sequential Function Chart
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Structured Text
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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.
Software Structure and Definition of Terms Programming
3-2 MITSUBISHI ELECTRIC
Program organisation units (POU’s) are
used to implement all programming tasks.