The schematic on this slide illustrates a point-to-point, differential, unidirectional network, which is the simplest RS-422 configuration. Since there is only one driver allowed on an RS-422 bus, there is no need for a driver enable pin, and there is only one termination resistor – typically 120 Ω for CAT 5 twisted pair – on the bus at the end farthest from the driver. In a unidirectional network transceivers are not required, because the master only transmits, and the slave is receive only. Therefore the network can be implemented with single transmitter and single receiver ICs, or with quad devices for multiple channels.