On Wed, May 3, 2017 at 11:32 PM, 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. > What is the maximum bit rate of the Pi's serial TXD & RXD? The 7i90 can accept RS422 up to 10M bits/second. Can the Pi take advantage that? Certainly an Intel PC could, Yes I agree conversion is cheap and easy, You can buy the Max chips on breakout boards with connectors for 50 cents each ebay.com/itm/2PCS-MAX485-Module <http://www.ebay.com/itm/2PCS-MAX485-Module-RS-485-Module-TTL-to-RS-485-Converter-For-Arduino/131694536431?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D40130%26meid%3De519e5e6252c4e40b7d0fa2b19dcd5fc%26pid%3D100005%26rk%3D6%26rkt%3D6%26mehot%3Dag%26sd%3D112076449800> In most cases it is best to buy the chips on boards with connectors. Saves you from a lot of work. People are using Cat5 (Ethernet cable) for all types of serial links now. It just works better as most links are now balanced pairs. > > 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 > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ 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
