140
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
6 What to Understand before Programming
6.2 Cautions on Creation of Fundamental Programs
6.2
Cautions on Creation of Fundamental Programs
This paragraph explains cautions on programming.
6.2.1
Programming procedure and execution order
1. Contact configuration and steps
Even for a sequence circuit offering a same operation, the program can be simplified and the number of steps
can be saved depending on the contact configuration method.
1) It is recommended to write a circuit with many serial contacts in an upper position.
2) It is recommended to write a circuit with many parallel contacts in a left position.
2. Program execution and programming order
A sequence program is executed "from top to bottom" and "from left to right".
Code the sequence instruction list in accordance with this rule.
(1)LD
(2)LD
(3)AND
(5)OUT
(4)ORB
(1)LD
(3)OR
(2)AND
(4)OUT
ORB instruction is not necessary
(1)LD
(3)OR
(5)OUT
(4)ANB
(2)LD
(1)LD
(2)OR
(3)AND
(4)OUT
ANB instruction is not necessary
(3)
(1)
(2)
(4)
(7)
(5)
(6)
(8)
(9)
(10)
(11)
Executed