It uses programmable memory to execute instructions for storing logical operations and sequential control, timing, counting, and arithmetic operations, and controls various types of mechanical equipment or production processes through digital or analog input (I) and output (O) interfaces. Programmable controllers are developed on the basis of electrical control technology and computer technology, and have gradually developed into a new type of industrial control device with microprocessors as the core, integrating automation technology, computer technology, and communication technology. PLC has been widely used in various production machinery and automatic control of production processes, becoming the most important, popular, and widely used industrial control device. It is recognized as one of the three pillars of modern industrial automation (PLC, robotics, CAD/CAM).