programmable controller (PLC) is a

programmable controller (PLC) is a new general automatic control sorting system which integrates traditional relay control technology, computer technology and communication technology. It has a series of advantages, such as enhanced function, simple programming, convenient use, small size, light weight and low power consumption. PLC application fields have been extended to various fields. During industrial production, the development of PLC produces a large number of switch sequence control. It operates sequentially according to logical conditions, controls interlocking protection actions according to logical relationships, and collects a large number of discrete data. traditionally, these functions are achieved through pneumatic or electrical control systems. PLC is the most basic and widely used type of switching value logic control. It replaces the traditional relay circuit and realizes logic control and sequence control. It can be used not only for the control of a single device, but also for group control and automatic assembly line of multiple machines. Such as injection molding machine, printing machine, stapler, combined rapid sorting system, grinding machine, packaging machine and so on. At present, PLC has been widely used in iron and steel, petroleum, chemical, electric power, building materials, machinery manufacturing, automobile, textile, transportation, environmental protection, cultural and entertainment industries at home and abroad. Nowadays, with the arrival of the information age, people's living standards are improving day by day. Convenient, fast, automatic, intelligent has become the theme of the times. In the modern family living environment, the family environment is not only limited to the physical space, but also pays more attention to the safe, convenient and comfortable environment. Automated electronic products naturally become the goal that people pursue. PLC will be the core of this design, design system structure diagram, program instructions, ladder diagram and input and output terminal distribution scheme. while retaining the basic function of raw material sorting machine, a series of practical functions are added to simplify the circuit structure. it will be convenient and flexible control. As long as the control program of input PLC is changed, the order of sorting machine can be changed, the multi-purpose flexible control of one machine can be realized, and the intelligent industry can be realized.