Programmable Logic Controller, referred to as PC or PLC, is an electronic system for digital operation, which is specially designed for application in industrial environments. It uses a memory that can be programmed to execute instructions for storing logic operations and sequence control, timing, counting, and arithmetic operations, and controls various types of operations through digital or analog input (I) and output (O) interfaces Type of machinery or production process. Programmable controller was developed on the basis of electrical control technology and computer technology, and gradually developed into a new type of industrial control device with microprocessor as the core, integrating automation technology, computer technology and communication technology. PLC has been widely used in the automatic control of various production machinery and production processes, and has become the most important, most popular, and most widely used industrial control device. It is recognized as the three pillars of modern industrial automation (PLC, robot, CAD/CAM) one.