A bidirectional point-to-point RS-422 network can be implemented by adding a return channel along a separate twisted pair. 8-lead full duplex transceivers without enables are typically used for this implementation. Because only one driver is allowed on an RS-422 bus, the master must have an extra receiver – connected to an additional bus - for each slave that it needs to respond to. A bidirectional RS-422 network is commonly used as an RS-232 “extension cord” to connect an industrial PC’s RS-232 port to a corresponding RS-232 port in a piece of remote equipment. The network may be unidirectional, or bidirectional as needed. The typically slow data rates of RS-232 coupled with the noise immunity of differential signaling allows extension cords of up to 4,000’ long. An RS-232 to RS-485 converter is required at both ends of the network, but this can be accomplished using one of Renesas' 2-port dual protocol devices such as the ISL3332.