PLC mainly refers to the programmable logic controller of digital operation electronic system, which is used to control the production process of machinery.
The origin of PLC
1968, American General Motors Company proposed to replace the relay control device. 1969, American Digital Equipment Company developed the first programmable controller PDP- 14, which was successfully tried on the production line of American General Motors Company, and was applied to electrical control by programmed means for the first time. This is the first generation of programmable controller, called programmable, which is recognized as the first PLC in the world.
1969, the United States developed the world's first PDP- 14.
197 1 year, Japan developed the first DCS-8.
1973, Germany developed the first PLC.
1974, China developed the first PLC.
Microprocessors appeared in the early 1970s. People soon introduced it into programmable controller, which made PLC increase the functions of calculation, data transmission and processing, and completed the industrial control device with real computer characteristics. At this time, PLC is the product of the combination of microcomputer technology and relay conventional control concept. After the development of personal computers, in order to facilitate and embody the functional characteristics of programmable logic controllers, programmable logic controllers were named as programmable logic controllers (PLC).