RS-232 / RS-422 / RS-485

RS-232:

RS-232 is a serial communication standard, which regulates asynchronous serial communication capabilities, as well as hardware flow control, software flow control, and check digits. Since this standard has been used for more than ten years, almost all digital communication devices have a control interface, and all use RS-232 as the communication interface. The typical communication distance is up to 15 meters at 9600bps.

RS-422:

RS-422 is a serial communication standard. It provides longer-distance communication capabilities than RS-232 and uses fewer signal lines. RS-422 data transmission uses differential signals as the technology, and the maximum rate can reach 10Mbps. At a speed of 9600bps, the communication distance can be up to 1.2 kilometers.

RS-485:

RS-485 is an enhanced version of RS-422. It uses 2-wire bus technology and is compatible with RS-422 interface. Using the RS-485 2-wire bus, you can build a very economical network. However, RS-485 only defines electrical signal characteristics but not others, so users must use their own software or protocol to control the RS-485 network.