Answer: In the industrial production process, a large number of switch quantities are sequentially controlled. It performs sequential actions according to logical conditions, and controls interlocking protection actions according to logical relationships, as well as a large number of discrete data collection. Traditionally, these functions are realized through pneumatic or electrical control systems. In 1968, GM (General Motors) of the United States proposed the requirement to replace relay control devices. The following year, American Digital Corporation developed a control device based on integrated circuits and electronic technology, and for the first time used programming methods for electrical control. This is the first generation of programmable controllers, called Programmable Controller (PC).
After the development of personal computers (abbreviated as PC), for convenience and to reflect the functional characteristics of programmable controllers, programmable controllers were named Programmable Logic Controller (PLC). Now, PLC is still often referred to as PC.
