These three communication ports are serial ports, which are different in the following aspects:
1. Communication distance
The maximum communication distance of RS232 port is 15 meters, while the maximum communication distance of rs422/485 port is 1200 meters.
2. Numbers of connected devices
RS232 can only connect to one device, while RS485 can connect to multiple devices.
3. Definition of RS232, RS422, and RS485 ports
RS232 is a standard interface. It is a D-type-9 needle. The signal definition of the interface of the connected device is the same.
While RS422/RS485 is a non-standard interface, usually a 15-pin serial interface (there are also 9-pin interfaces), and the pin definition of each device is different. In addition, it needs to be explained that there are differences between RS422 and RS485: RS422 is 4-wire system, full duplex mode; RS485 is two-wire system, half duplex mode.
Both of RS232, RS422 and RS485 is standard serial data interface. RS232 is the most widely used serial interface in PC communication. RS232 is defined as a single-terminal standard for increasing communication distance in low-rate serial communication. RS232 adopts unbalanced transmission mode, which is called single-terminal communication, while RJ45 interface is usually used for data transmission, the most common application is network card interface.