A.According to the number of serial ports, it can be divided into 1 port, 2 ports, 4 ports, 8 ports, 16 ports, 24 ports, 32 ports, etc.
B.According to the type of serial port, it can be divided into RS232, RS422, RS485, and RS232/422/485 trinity, or RS232/485 two-in-one.
C.According to the physical form of serial interface, it can be divided into DB9 interface (standard RS232 type), RJ45 interface (mostly RS232/422/485 type) and terminal interface (mostly 485 type).
D.According to the type of protection, it can be divided into the type with or without isolation protection.
