History of PLC
In the industrial production process, a lot of switching sequence control, which in accordance with theplc programmable intelligent controller conditions of the order to move a logical and controlled chain protection action in accordance with the logic of relations, and a large number of discrete data collection. Traditionally, these functions are controlled by pneumatic or electrical system to achieve. 1968 American GM (General Motors) companies to replace the electrical control device, following the requirements of the second year, the United States developed a digital control device company based integrated circuits and electronic technology, for the first time using procedural means used in electrical control, which is the first generation of high speed counter plc, said the Plc high speed counting modules Programmable Controller (PC). After a personal computer (referred to as PC) to develop, in order to facilitate, but also to reflect the high speed counter plc's features, programmable logic controller named Programmable Logic Controller (PLC), and now, still often referred PLC PC.