An adapter circuit consisting of an RS-485 transceiver (MAX3076 or MAX13086) and a voltage monitor used as a timer (MAX641X) allows an existing point-to-point full duplex circuit to function in a more-complex point-to-multipoint half-duplex system.
Thanks rsdio!
What device benefits from half duplex?
or
What would this be useful for?
THANKS GUYS!
Half-Duplex RS485 is more commonly called RS-422. It is much like RS-232 serial comms, except for using balanced line drivers and receivers.
Just like RS-232, there are several advantages. The main advantage, though, is that you do not have to worry about buss contention (there is only one transmitter per line pair) and you don’t have to worry about switching the line driver to and from TX mode.
RS-422 is generally regarded as a fairly robust long distance protocol. Depending upon baud rate and the quality of the twisted-pair cable used, its good for 4000 feet or more. I have successfully used it for more than a mile. RS-232 just can’t go that far.
I have digital dispaly with rs485 output and remote digital display with rs485 input,but nothing indicating in remote display when try to connect both.