1） When a negative jump (on/off) is detected in the specified bit, the contact opens for one scanning cycle

2） For non falling edge instructions, the specified bit contact allows the stack top value to be set to 0 each time when bit 1 to 0 (ON → OFF) transition is performed during a scan; Otherwise, set it to 1;

3） The instruction will continue to execute unless a negative jump is detected in the specified bit, and the instruction will only disconnect for a moment (PLC scan cycle). Commonly used for signal triggering in sequential control, cannot be used as an output (external coils may not absorb, this should be noted);

4） Special attention should be paid when using this instruction, as the contact will only be connected when the system detects a change in the falling edge. Improper handling during actual use may result in missing the opportunity and prevent it from happening.

Input/Output	Data Type	operand	Description
IN	ON/OFF	X/Y/M/C/T/S, word to Bit(D/V/Z), Lacal variable(LB)	input

Instruction table:

NETWORK 000

LDFI X000

AND X001

OUT Y000

POP

图1 LDFI