What is RS-232C/RS-422/RS-485?
RS-232C is an interface condition (electrical and mechanical connection condition) between data communication devices such as computers, which is defined by the EIA (American Electronics Industry Association).
RS-422 is a balanced interface that is more resistant to noise than RS-232C.
RS-485 is basically the same as RS-422. However, RS-422 is applicable to one-to-one transmission, while RS-485 is applicable to bus system.