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3.1 Sequence Program
3.1.1 Sequence program description method
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SEQUENCE PROGRAM EXECUTION
3.1.1 Sequence program description method
The sequence program is created with the ladder mode of GX Developer.
The ladder mode is based on the concept of a sequence circuit of relay control. It
enables programming in representation close to a sequence circuit.
In the ladder mode, programming is performed in ladder block units.
A ladder block is the minimum unit for performing sequence program operation, which
starts from the left side vertical bus bar and ends at the right side vertical bus bar.
Diagram 3.3 Ladder mode
Y121
Y122
Y123
Y124
Y120
Y124
0
2
8
Left side vertical bus bar N/O contact N/C contact
Coil (output)
Right side
vertical bus bar
Ladder block
Step number
X100 to 105 indicate inputs.
Y120 to 124 indicates outputs.
X100
X103
X104 X105
X101 X102
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