Rs485 is somewhat similar to USB as in there are two wires. Look here: **broken link removed**
Think of the two wires, the twisted pair transmission line gets terminated at each end. You worry about your end and the device it's connected to worries about that end.
Your terminating the medium of transmission at the ends of the line, not the chip per se. Xmit and receive use the same medium, thus one set of two terminators total. One at each end.
Missing concept: Either the transmitter or receiver is enabled, not both at the same time.