A programmable logic controller (PLC) is a type of digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures. PLCs are used in many industries and machines. They are designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed-up or non-volatile memory. PLCs read limit switches, analog process variables (such as temperature and pressure), and the positions of complex positioning systems. On the basis of the input data, the PLC can control lights, motors, valves, pumps and other industrial components.