Tag Archives: nop command

No-operation command NOP for S7-200 PLC

NOP is a null operation instruction, used in ladder diagrams and instruction lists. If you need to shield an output, use NOP instead.

NOP does not carry any operands. Inserting a NOP instruction between normal instructions has no effect on the program. However, if the written instruction is replaced with a NOP instruction, the changed program is deleted and the program changes, so the NOP instruction can be used. Edit the program.

NOP instruction format

Use of Mitsubishi PLC NOP command

The Mitsubishi PLC instruction NOP is a null operation instruction, which is mainly used for short circuit, changing circuit function and program debugging.

Adding some empty operation instructions to the program has no effect on the logical operation result, but when the program is changed later, the empty operation instruction is replaced by other instructions, which can reduce the program number change.

The following figure shows an example of the NOP instruction application. The number of empty operation instructions can be increased as needed.

Example of NOP instruction for OMRON CPM1A series PLC

NOP is a no-op command

By using NOP instead of AND N, you can short the contact N in the AND statement.

Use NOP instead of OR N to break contact N in the OR statement

Instruction example

Delete the contact 00001 in the ladder diagram.

PLC NOP instruction description

NOP instruction. Also known as the “null operation instruction”, its main function is: when debugging the program, use it to replace some unnecessary instructions, that is, delete the program composed of these instructions, but now the function of the programmer is getting stronger and stronger, when modifying the program Instructions can be deleted directly and the NOP instruction rarely used. Second, the NOP instruction in the program can extend the scan cycle.

Null operation command (NOP) of FX series PLC

NOP (No Operation): Empty operation command. No action, no operand steps.

Add a null operation instruction to the program to reduce the change of the step number when changing or adding the instruction. The circuit can be changed by replacing some of the written instructions with the NOP instruction. When the program is completely cleared, all instructions become NOP.