Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!uwm.edu!linac!att!pacbell.com!ames!lll-winken!telecom-request From: 0004133373@mcimail.com (Donald E. Kimberlin) Newsgroups: comp.dcom.telecom Subject: Re: RS-485 Information Wanted: URGENT Message-ID: Date: 25 Mar 91 02:05:00 GMT Sender: Telecom@eecs.nwu.edu Organization: TELECOM Digest Lines: 33 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 236, Message 10 of 12 In article , Markus Fischer 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.