Nop - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
7.14

NOP

Outline
NOP instruction specifies no operation.
When a program is erased completely, all steps are replaced with NOP instructions.
When NOP instruction is located between general instructions, PLCs ignore NOP instruction.
If NOP instructions are put in the middle of a program, fluctuation of step numbers is minimized when the
program is changed or added. But excessive program steps are required.
Note that circuits are considerably changed if already written instructions are replaced with NOP instructions.
1. Instruction format
NOP
No Operation
2. Applicable devices
Bit Devices
Instruc-
System User
tion
X Y M T C S D .b KnX KnY KnM KnS T C D R U \G
NOP
Explanation of function and operation
1. NOP instruction (no operation or null step)
NOP instruction specifies no operation.
If NOP operation is written in the middle of a program, PLCs ignore it in executing the program.
When an existing program is replaced with NOP instructions, it means that former instructions are deleted.
AND → NOP
Contact becomes
short-circuit.
224
Mnemonic
Basic Instruction
NOP
1 step
−
Digit Specification
ANI → NOP
Operation Condition
Continuous
Operation
Pulse (Single)
Operation
Word Devices
Special
System User
Unit
V Z Modify K H
There are no applicable devices.
OUT → NOP (error)
OR → NOP
ORI → NOP
7 Basic Instruction
Others
Con- Real Charac-
Index
stant Number ter String
E " "
Circuit is
disconnected.
7.14 NOP
Pointer
P