The SN75LBC786 is a monolithic quadruple RS-423-B driver and receiver with integratedloopback function. The operation of the SN75LBC786 is closely based on that of the SN75186. In normal operation, the device performs as four independent RS-423-B driver/receiver pairs designed to interface data-terminal equipment (DTE) with data circuit-terminating equipment (DCE). In loopback mode, the signal from each driver output is fed back via special circuitry into its associated receiver input, removing the need to locally disconnect cables and install a loopback connector. The receiver output signal is the same as the driver input signal.