UART communication protocol

Serial communication means that the serial port sends and receives bytes according to the number (bit). Although the serial communication rate of bytes is slower, serial ports can use a single wire to send data while using another wire to receive data. Serial communication protocol means that when the content of the data packet has been specified, and the content includes the start bit, main data, check bit and stop bit, the sender and the receiver need to agree on a consistent data packet format to be able to operate normally. Specifications for sending and receiving data. In serial communication, commonly used protocols include: RS-232, RS-422 and RS-485.

Commonly used protocols:

RS-232 (ANSI/EIA-232 standard) is the serial connection standard on IBM-PC and its compatibles. There are many uses, such as connecting a mouse, printer or Modem, and also connecting to industrial instruments and meters. For the improvement of drive and connection, the transmission length or speed of RS-232 in practical applications often exceeds the standard value of the general standard. RS-232 is limited to point-to-point communication between the PC serial port and the device (the maximum distance of RS-232 serial port communication is 50 feet).

RS-422 (EIA RS-422-AStandard) is the serial connection standard for Apple's Macintosh computers. RS-232 uses unbalanced ground-referenced signals, while RS-422 uses differential signals. Differential signal transmission uses two wires to send and receive signals. Compared with RS-232, it has better noise immunity and longer transmission distance, and in industrial applications, this will be a very big advantage.

RS-485 (EIA-485 standard) is an improved version of RS-422, because it increases the number of available devices from 10 to 32, and defines a certain number of devices in the case of the maximum number of devices. Some electrical characteristics to ensure that there can be enough signal voltage output. With the capability of multiple devices, you can also use a single RS-485 port for device networking. RS-485, with its excellent noise immunity and multi-device availability, is the choice for serial data connections in the establishment of distributed device networks connected to PCs, other data collection controllers, HMIs, or other operational industrial applications. RS-485. RS-485 is a superset of RS-422, so virtually all RS-422 devices can be controlled by RS-485. In addition, RS-485 can also use about 4000 feet (ultra long distance) line for serial data communication. Преобразователь RS485 в TCP/IP