How logic gates work: AND OR NOT NAND NOR XOR

Logic gates are the fundamental building blocks for all digital circuits including devices like cellphones, laptops and of course PLCs.  Sometimes, in PLC programs, we use logic gates explicitly but they are always there behind the scenes in every function. The gates perform basic logical functions like AND. (Are both signals "ON"?)

In the program the logic gate outputs will go on or off based on combination of digital signals coming to the inputs. The logic gates are based on boolean algebra (on or off). Most logic gates need two or more input signals and will have one output signal. The output signal of a logic gate can go to another logic gate or an external output signal.

Every logic gate in the program will be in ON or OFF state. The binary conditions are often referred to as false or true. In Zeliosoft its referred to ON or OFF. OFF represents 0 (or 0v), and ON represents 1 (or 24v). Depending on the type of logic gate being used and the combination of inputs, the binary (boolean) output will differ. A logic gate can be thought of as a switch.