Simple comparison between RS232 and USB

RS-232 is a serial data communication interface standard developed by the Electronic Industries Alliance of America, the original number is EIA-RS-232 (RS232 for short), which is widely used for the connection between DCE (Data Communication Equipment) and DTE (Data Terminal Equipment). DCE can be understood as data communication end, such as modem equipment; DTE can be understood as data terminal, such as a computer.Currently, RS232 interface is commonly used as a debugging port in instrumentation, PLC and embedded fields.RS232 interface is divided into male and female connectors。

USB, short for Universal Serial Bus, is an external bus standard used to standardize the connection and communication between computers and external devices. The USB interface supports plug-and-play and hot-swappable functions for devices. USB was jointly proposed by Intel, Compaq, IBM, Microsoft and many other companies at the end of 1994.

RS-232 and USB are both serial communications, but they are completely different in terms of underlying signals, level definitions, mechanical connection methods, data formats, communication protocols, etc. RS-232 is a popular interface. In MS-DOS, the four serial interfaces are called COM1, COM2, COM3 and COM4, while the vast majority of windows applications can have up to four peripherals, but if the user wants to expand more peripherals, it has to be implemented with a plug-in serial card or an external switch box. RS-232 point-to-point connection, only one peripheral can be connected to one serial port.

While USB is a multi-point, high-speed connection, the use of hubs can achieve more connections. the basic part of the USB interface is the serial interface engine SIE, SIE receives data bits from the USB transceiver, converted into valid bytes transmitted to the SIE interface; conversely, the SIE interface can also receive bytes converted into serial bits sent to the bus. the RS-232 system consists of 2 serial signal paths that are in opposite directions and are used to transmit commands and data, respectively, while commands and status must be interleaved with data; whereas USB supports separate command and data channels and allows independent status reporting.