The MAX3079E can be configured as either a full-duplex or a half-duplex transceiver by controlling the logic at pin H/F. In half-duplex mode, the pins A and B are disconnected internally and the pins Y and Z both transmit and receive signals as depicted in the datasheet on page 21.
To set up a system that can switch between half-duplex and full duplex you will need an external switch to either connect the lines at Y and Z for transitting and receiving or switch to a second pair of lines for RS-422 reception, while leaving Y and Z for RS-422 transmission.