0004133373@mcimail.com (Donald E. Kimberlin) (03/25/91)
In article <Digest v11,iss230>, Markus Fischer<FISHER@sc2a.u nige.ch writes: > I need information about the RS 485 communication norm. Specifically, > I need cabling schematics, signal IDs and signal levels. I would > prefer the answers in e-mail, and I promise I'll post the information > to the net. Uh-uh ... that's a no-no, Markus! Standards of the Electronics Industry Association are copyrighted material, just as are the standards of any other nation's standards body or any international standards organization. The *proper* place to get EIA documents is by mail order from EIA's Washington, DC address. HOWEVER, you may be surprised at how close you can find some people who know by just wandering across Geneva to 2, rue du Varembe, asking around the ITU HQ for who's there that attends CCITT Study Group XVII, the datacomm standards group. Many of its participants, at least those from North America, also participate in the EIA meetings back in the U.S. In fact, the CCITT Bookstore may even have EIA documents in stock for sale. For a surface run-down, RS-485 is an implementation of RS-422 signal levels (which are essentially CCITT V.10) in a four-wire, full- duplex manner to provide up to 32 polled data terminals up to 57,600 bps on local wire. If you don't really want to build the interface, some manufacturers have been making RS-232 (V.24/28) to RS-485 adapters since late 1984. The one I know of is ARK Electronic Products of Melbourne, FL, since absorbed into AT&T/Paradyne of Largo, FL. When you get past the droids at Paradyne, you can probably get some without much trouble.
rfarris@rfengr.com (Rick Farris) (03/26/91)
In article <telecom11.236.10@eecs.nwu.edu> 0004133373@mcimail.com (Donald E. Kimberlin) writes: > If you don't really want to build the interface, some > manufacturers have been making RS-232 (V.24/28) to RS-485 > adapters since late 1984. The one I know of is ARK > Electronic Products of Melbourne, FL, since absorbed into > AT&T/Paradyne of Largo, FL. Even better, *Inmac* carries in-line RS-232 <--> RS-485 converters, and will ship today with delivery tomorrow. Inmac charges full list price on everything they sell, but if you call them today they will ship today, *and they ship on open account on the first call with no credit checks or other hassles.* While expensive, I have found nothing at Inmac that wasn't of the highest quality. I'm particularly fond of their T-switches. I call Inmac at 1-800-547-5444. As to the actual packet protocol over RS-485, I have written drivers and would be happy to answer specific questions. Rick Farris RF Engineering POB M Del Mar, CA 92014 voice (619) 259-6793 rfarris@rfengr.com ...!ucsd!serene!rfarris serenity bbs 259-7757