The serial interface is abbreviated as serial port, also called serial communication interface or serial communication interface (usually referred to as COM interface). It is an expansion interface that uses serial communication. Serial Interface (Serial Interface) refers to the sequential transmission of data one by one. It is characterized by simple communication lines, as long as a pair of transmission lines can achieve two-way communication (you can directly use the telephone line as a transmission line), thus greatly reducing costs. Especially suitable for long-distance communication, but the transmission speed is slow.
The communication method in which bit data of one message is transmitted bit by bit is called serial communication. The characteristics of serial communication are: the transmission of data bits, bit-sequential, at least a single transmission line; low cost but slow transmission speed. The distance of serial communication can be from a few meters to several kilometers; according to the direction of information transmission, serial communication can be further divided into simplex, half duplex and full duplex.
The appearance of the serial port is around 1980, the data transmission rate is 115kbps-230kbps. The initial stage of the serial port is to achieve the purpose of connecting the computer peripherals. The initial serial port is generally used to connect the mouse and external Modem and old-fashioned cameras and tablet devices. The serial port can also be applied to the interconnection and data transmission between two computers (or devices). Because the serial port (COM) does not support hot plugging and the transmission rate is relatively low, some new motherboards and most portable computers have begun to cancel the interface. At present, serial ports are mostly used in industrial control and measurement equipment and some communication devices.