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FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
1 Introduction
1.1 Programming Language in PLCs
1. Introduction
This chapter explains basic items related to programming in FX3G, FX3U and FX3UC programmable controllers (PLCs).
1.1 Programming Language in PLCs
This section explains the features of programming in FX3G, FX3U and FX3UC PLCs.
1.1.1 Types of programming languages
FX3G, FX3U and FX3UC PLCs support the following three types of programming languages:
1. List programming
This method is the basis of programs.
1) Features
In this method, sequence instructions are input in the form of instruction words such as "LD", "AND" and "OUT".
This input method is the basis of sequence programs.
2) Example of list display
2. Circuit programming
In this method, ladder formats are drawn on the graphic screen.
1) Features
In a circuit program, a sequence circuit is drawn on the graphic screen by sequence formats and device numbers.
Because a sequence circuit is expressed with contact symbols and coil symbols, the contents of a program can
be understood easily.
In the circuit display status, the PLC operations can be monitored.
2) Example of circuit display
3. SFC (STL <step ladder>) programming
This input method allows sequence design in accordance with the flow of machine operations.
1) Features
In an SFC (sequential function chart) program, sequences can be designed in accordance with the flow of
machine operations.
2) Compatibility between SFC programs and other programs
SFC programs can be converted into another program format. And when list programs and circuit programs are
created according to certain rules, they can be converted inversely into SFC programs.
Step Instruction Device number
0000 LD X000
0001 OR Y005
0002 ANI X002
0003 OUT Y005
…
…
…
X000
Y005
X002
Y005
The above list program is expressed in
the circuit diagram.