In a ladder diagram, when the specified bit=1 (ON), the normally open contact is closed (connected); when the specified bit =0 (OFF), the normally closed contact is closed (disconnected).

In the instruction table, normally open contacts are represented by LD (load), AND (and), and OR (or) instructions, which place address bit values at the top of the stack.

In the function block, there are no directly used LD instructions, and the conditions are directly input into a single function block.

Input/Output	data type	operands	description
IN	ON/OFF	X/Y/M/C/T/S, word to bit(D/V/Z), local variable(LB)	输入

Instruction table:

NETWORK 000

LD X000 // Load input coil X000, X000 must be equal to 1 to activate X000

OR X002 // Perform an 'OR' operation with input coil X002

AND X001 // Perform 'AND' operation with input coil X001

OUT Y000 // Output coil Y000

图1 LD