On 04/07/2013 11:08, Dennis Poon wrote: > thanks. I am not using the fpc email as it seems off topic. > > May I know the exact brand and model number of the adapter you used? > I have an ATEN usb-to-serial cable (UC-232A) but I am not sure how to > connect its serial pins to rs-485 's DIFFERENTIAL LINES and how to > set that adapter into half-duplex translation mode. > > Dennis > [...]
(apparently it went into FPC list anyway) For RS485 adaptation, use a MAX232 like chip (to convert +-12 to ttl) and then a RS485 transceiver chip; A MAX232 has 4 [IIRC] level changers, 2 in each direction; so you can use one pair to convert tx/rx, and one of the remaining ones in 232-ttl direction, to convert one RS232 signal to switch the RS485 trx into 'sending' mode; Of course you need an additional +5V supply to the above too. HTH, -L. _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal