 Standards such as EIA-530 (DB-25 connector) and EIA-449 (DC-37 connector) use RS-422 electrical signals.Some RS-422 devices have 4 screw terminals for pairs of wire, with one pair used for data in each direction.RS-422 cannot implement a true multi-point communications network such as with EIA-485 since there can be only one driver on each pair of wires.