Farnell have plenty of RS422 and RS485 drivers http://se.farnell.com/c/halvledare-ic-kretsar/drivkretsar-granssnitt/rs232-rs422-rs485-drivkretsar
Some extra capacitances might be a good idea to avoid voltage drop at power supply rail if there is capacitance between the differential lines. This is not a problem since capacitors are cheap but voltage drop might be and unless you think about it hard to figure out. On Thu, 4 May 2017 16:32:41 +1000 Erik Christiansen <[email protected]> wrote: > On 03.05.17 22:40, Gene Heskett wrote: > > On Wednesday 03 May 2017 22:29:43 Chris Albertson wrote: > > > RS422 is balanced and opt isolated at the Mesa card end so you likely > > > have better noise resistance then with SPI. > > > > rs485 is the single ended cousin. Could a atom board keep up with that > > with a pci-e rs422 card in it? That does have a bit of an attraction, > > particularly from the noise safety dept. Silly Q: can the pi do rs422 > > over its gpio? > > Hook a RS485/RS422 transceiver to a Pi's serial TXD & RXD, and terminate > each end of the twisted pair cable in 120 ohms, then it's done. All the > chip does is TTL/CMOS to differential Tx & Rx. > > I bought some surplus DS3695A RS485/RS422 half-duplex transceivers a few > days ago for US30c each, but they draw over 27 mA, idling, - a MAX485 > gets by on 300 uA, though it'll only do 2.5 Mb/s. The SN65HVD485 will do > 10 Mb/s on long lines, and draw 1 to 2 mA. (They may be the one Jon > likes?) > > Just watch pinout, driver enable logic, and whether it's full/half > duplex. The former has separate Tx & Rx cables (4 wires) vs 2 wires. > > Incidentally, it's the RS485 which is multipoint - just in case you want > that, and go to put plastic down. > > Erik > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users -- Nicklas Karlsson <[email protected]> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
