When the specified bit = 0 (OFF), the normally closed contact is immediately closed (connected), and when the specified bit=1 (ON), the normally closed contact is immediately closed (disconnected). The specified bit does not rely on PLC scanning cycles for updates, it will be updated immediately.

In the instruction table, immediately normally closed contacts are represented by LDIIM (immediately load not), ANDIIM (immediately and not), and ORIIM (immediately or not) instructions, which place the logical NOT (not) of the address bit value at the top of the stack and execute it immediately.

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

Instruction table:

NETWORK 000

LDIIM X000 // Immediately load the logic NOT of the input coil X000, X000 must be equal to 0 to activate X000

ORIIM X002 // Perform 'immediate or non' operation with input coil X002

ANDIIM X001 // Perform 'immediate and non' operation with input coil X001

OUT Y000 // Output coil Y000

图1 LDIIM