Programmable Logic Controller is a digital computing operation electronic system specially designed for application in industrial environments. It uses a programmable memory that stores instructions for performing operations such as logic operations, sequence control, timing, counting, and arithmetic operations, and controls various types of mechanical equipment or production through digital or analog input and output. process.
Programmable Logic Controller (PLC), a digital arithmetic controller with microprocessor for automatic control, can store and execute control commands at any time. The programmable controller consists of CPU, instruction and data memory, input/output interface, power supply, digital analog conversion and other functional units. The early programmable logic controllers were only logically controlled, so they were named programmable logic controllers. Later, with the continuous development, these simple computer modules have been equipped with logic control, timing control, analog control, Various functions such as multi-machine communication, the name is also changed to a programmable controller (Programmable Controller), but because its shorthand PC and personal computer (Personal Computer) shorthand conflict, plus the habit of reason, people often use The term logic controller is programmed and the abbreviation of PLC is still used.
The programmable logic controllers currently used in the industry are quite close to or close to the host of a compact computer, and its advantages in terms of scalability and reliability make it widely used in various industrial control fields. Whether in the computer direct control system or the centralized distributed control system DCS, or the fieldbus control system FCS, there are always a large number of use of various types of PLC controllers.