PLC Development History

origin
The development of the production technology requirements of the American automobile industry promoted the emergence of PLC. In the 1960s, when General Motors of the United States was adjusting its factory production lines, it found that the relay and contactor control systems were difficult to modify, large in size, noisy, and inconvenient to maintain. The reliability was poor, so the famous "Ten Common" bidding indicators were proposed.
In 1969, the U.S. Digital Equipment Company developed the first programmable controller (PDP-14). After trialling it on the General Motors production line, the effect was remarkable; in 1971, Japan developed the first programmable controller (PDP-14). DCS -8); in 1973, Germany developed the first programmable controller; in 1974, China began to develop programmable controllers: in 1977, China promoted PLC in industrial applications.
The original purpose was to replace mechanical switching devices (relay modules). However, since 1968, the functions of PLC have gradually replaced relay control boards, and modern PLCs have more functions. Its use extends from single process control to the control and monitoring of entire manufacturing systems.
develop
Microprocessors appeared in the early 1970s. People quickly introduced it into programmable logic controllers, which added computing, data transmission and processing functions to the programmable logic controllers, completing industrial control devices that truly have computer characteristics. The programmable logic controller at this time is a product of the combination of microcomputer technology and conventional relay control concepts. After the development of personal computers, in order to facilitate and reflect the functional characteristics of programmable controllers, the programmable logic controller was named Programmable Logic Controller (PLC).
In the mid-to-late 1970s, programmable logic controllers entered the stage of practical development. Computer technology has been fully introduced into programmable controllers, which has made a leap in their functions. Higher computing speed, ultra-small size, more reliable industrial anti-interference design, analog calculation, PID function and extremely high cost performance have established its position in modern industry.
In the early 1980s, programmable logic controllers have been widely used in advanced industrial countries. There are more and more countries producing programmable controllers in the world, and their output is rising day by day. This marks that programmable controllers have entered a mature stage.
From the 1980s to the mid-1990s, programmable logic controllers developed fastest, with an annual growth rate of 30 to 40%. During this period, PLC's analog processing capabilities, digital computing capabilities, human-machine interface capabilities and network capabilities have been greatly improved. Programmable logic controllers have gradually entered the process control field, replacing their dominant position in the process control field in some applications. Dominant DCS system.
At the end of the 20th century, the development of programmable logic controllers was characterized by being more adaptable to the needs of modern industry. During this period, mainframes and ultra-small computers were developed, various special function units were born, and various human-machine interface units and communication units were produced, making it easier to match industrial control equipment using programmable logic controllers.