A TIA/EIA standard for serial interfaces that extends distances and speeds beyond RS-232. RS-422 is a balanced system requiring more wire pairs than its RS-423 counterpart and is intended for use in multipoint lines. Both use either a 37-pin connector defined by RS-449 or a 25-pin connector defined by RS-530.
RS-449 and RS-530 specify the pin definitions for RS-422 and RS-423. RS-422/423 specify electrical and timing characteristics. See RS-530