Digital electronic systems in indus

Digital electronic systems in industrial environments use dedicated programmable controllers. It also controls various machinery or production processes through digital or analog inputs/outputs. The design of PLC and its related peripherals is easy to integrate and extend with industrial control system.In short, a computer designed and manufactured specifically for industrial environmental applications is a PLC. But PLC products are not specific to specific industrial applications. In the practical application, its hardware needs to be selected and configured according to the actual needs, and its software needs to be selected and configured according to the "design and compilation of control requirements".2.2 Development history of PLCAlthough PLC appeared in a short period of time, with the emergence of the microprocessor, scale, the rapid development of VLSI technology and the continuous progress of data communication technology, PLC also got rapid development. Its development process can be roughly divided into three stages:1. Early PLC. At this point, THE PLC more or less to replace the relay control device. It appears as a quasi-computer on hardware and has been modified on the I / 0 interface circuit to meet the requirements of the industrial control field. The device mainly USES discrete components and small and medium integrated circuits to store core memory. The ladder diagram of relay control circuit familiar to electrical engineers and technicians is used in software programming. It is easy to understand, easy to install, small size, low energy consumption advantages. So far, PLC programming languages such as troubleshooting reusable ladder diagrams have been widely used.2. In recent years, PLC (from the mid-1980s to the present) entered the mid-1980s and the late 1980s. With the rapid development of VLSI technology, the market price of microprocessors has dropped, and all kinds of microprocessors used by PLC have been generally improved. In addition, in order to further improve the processing speed of PLC, so, the PLC's software and hardware functions have changed a lot. The manufacturer specially developed the logic processing chip.