The SN65LBC184 and SN75LBC184 devices are half-duplex, RS-485 transceivers commonly used for asynchronous data transmissions. The driver and receiver enable pins allow for the configuration of different operating modes.

Figure 8-1 Half-Duplex Transceiver Configurations

1. Using independent enable lines provides the most flexible control by allowing the driver and the receiver to be turned on and off individually. This configuration requires two control lines, allowing the selective listening into the bus traffic, whether the driver is transmitting data or not.
2. Combining the enable signals simplifies the interface to the controller by forming a single direction-control signal. In this configuration, the transceiver operates as a driver when the direction-control line is high, and as a receiver when the direction-control line is low.
3. Only one line is required when connecting the receiver-enable input to ground and controlling only the driver-enable input. In this configuration, a node not only receives the data from the bus, but also sends and verifies the correct data has been transmitted.