The SN65HVD17xx family consists of both half-duplex and full-duplex transceivers that can be used for asynchronous data communication. Half-duplex implementations require one signaling pair (two wires), while full-duplex implementations require two signaling pairs (four wires). The driver and receiver enable pins of the SN65HVD17xx family allow for control over the direction of data flow. Since it is common for multiple transceivers to share a common communications bus, care should be taken at the system level to ensure that only one driver is enabled at a time. This avoids bus contention, a fault condition in which multiple drivers attempt to send data at the same time.