The ISO308T consists of an RS-485 transceiver commonly used for asynchronous data transmissions. Full-duplex implementation requires two signal pairs (four wires), and allows each node to transmit data on one pair while simultaneously receiving data on the other pair. To eliminate line reflections, each cable end is terminated with a termination resistor, R(T), whose value matches the characteristic impedance, Z0, of the cable. This method, known as parallel termination, allows for higher data rates over longer cable length.

Figure 9-1 Half-Duplex Transceiver Configurations