Date: Fri, 16 Feb 1996 09:51:33 -0500 (EST) From: Chuck Robey <chuckr@glue.umd.edu> To: Michael Smith <msmith@atrad.adelaide.edu.au> Cc: "Jordan K. Hubbard" <jkh@time.cdrom.com>, msmith@atrad.adelaide.edu.au, hackers@FreeBSD.ORG Subject: Re: Multidrop serial (422/485) driver Message-ID: <Pine.SUN.3.91.960216094756.1126A-100000@espresso.eng.umd.edu> In-Reply-To: <199602160756.SAA27443@genesis.atrad.adelaide.edu.au>
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On Fri, 16 Feb 1996, Michael Smith wrote: > Jordan K. Hubbard stands accused of saying: > > > > > The 'mdsio' driver provides support for multidrop serial busses, either > > > using a standard RS-422/485 interface card, or a standard RS-232 serial > > > port with DTR- or RTS-controlled transmit/receive. > > > > Uh. Interesting. I wasn't aware that anyone was still playing with > > serial networks since they dismantled BERKNET. :-) > > > > Are you guys actually using this stuff in such an application? > > It's called "industrial control". RS-485 is very heavily used in > machine interfaces; properly wired it's nearly immune to interference, > you can run it hundreds of metres over telephone cable, and it takes a > $0.75 part to interface it to almost any UART or microcontroller. > > The 2000 olympics stadium at Homebush in Sydney is riddled with the stuff > (cue Michael Butler 8), we use it for communications between our > data acquisition systems and the associated radar transmitters; with > an optically-isolated interface it doesn't suffer for being run in the > same cable trays as the main antenna feeds (100KW+ @54MHz). One other common application: light boards in theatres. One common system that's out there run by the use of RS-485. Amateur theatre groups would be fascinated by a free system to control their lights for them. The protocol is public ... > > > Jordan > > -- > ]] Mike Smith, Software Engineer msmith@atrad.adelaide.edu.au [[ > ]] Genesis Software genesis@atrad.adelaide.edu.au [[ > ]] High-speed data acquisition and (GSM mobile) 0411-222-496 [[ > ]] realtime instrument control (ph/fax) +61-8-267-3039 [[ > ]] Collector of old Unix hardware. "I seek PEZ!" - The Tick [[ > ----------------------------+----------------------------------------------- Chuck Robey | Interests include any kind of voice or data chuckr@eng.umd.edu | communications topic, C programming, and Unix. 9120 Edmonston Ct #302 | Greenbelt, MD 20770 | I run Journey2 and n3lxx, both FreeBSD (301) 220-2114 | version 2.2 current -- and great FUN! ----------------------------+-----------------------------------------------
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