EIA 422: Former RS 422, is a 4 wire Communication Standard for Serial signal transmission between a computer and peripheral devices. The maximum distance is 4000 feet (1200 m). One driver can be connected to up-to 10 receivers. .
EIA 485: Former RS 485, is a 2-wire Communication Standard for Serial signal, multi point transmission. The maximum distance is 4000 feet (1200m). The standard specifies up to 32 drivers and 32 receivers on a single buss.
ENV 50091: European Standard: Equivalent to IEC 62040, published by Cenelec. See IEC 62040