Date: Sun, 7 Sep 1997 23:13:24 -0700 (PDT) From: "Jamil J. Weatherbee" <jamil@counterintelligence.ml.org> To: Mike Smith <mike@smith.net.au> Cc: Joerg Wunsch <joerg_wunsch@uriah.heep.sax.de>, hackers@FreeBSD.ORG, jamil@acromail.ml.org Subject: Re: Speaking of device drivers. Message-ID: <Pine.BSF.3.96.970907225525.1391B-100000@counterintelligence.ml.org> In-Reply-To: <199709080141.LAA00840@word.smith.net.au>
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On Mon, 8 Sep 1997, Mike Smith wrote: > > (Please, for your sake, try to learn something about the concept of the > "paragraph" and the "sentence".) > > > I am currently working on a piece of software (actually an expansion of an > > earlier product), in house as a consultant for a small company. It > > involves the coordination of a horrendous number of sensors/actuators > > attached to a number of networked freebsd machines. > > Can you qualify "horrendous"? Unless there's something *really* > horrendous about it, I think you're already off on the wrong foot. > > > Like I've said this is a > > work in progress but I think that the concept could be generalized a bit > > more to include the equivalent of nfs for character devices -- my > > authentication right now is by serial keys and device description shared > > by client and server. > > Sounds like a lot of overkill, IMHO. This isn't the sort of thing you > want in an industrial environment. I didn't really have a word in this respect, I am just supposed to deliver a working software--- people put hardware together demonstrate that it functions correctly and then expect it all linked. > > >From my POV I would be using one or more RS-485 links and either custom > slaves at suitable points or off-the-shelf 485 slaves like the > Advantech ADAM modules. The only time this breaks down is when you > have precise timing requirements between multiple slaves, and often the > easiest way to go then is to have a separate transmit-only time-sync > bus. I actually have looked into this I've done some significant programming on a 68hc11 board with RS485 ports, also I am working on an unrelated solutions to another problem on the 68hc11KA4 a truly versatile processor (unfortunately Motorola has a little manufacturing problem and they are very hard to get for your run of the mill embedded solutions), in fact if it was up to me I would of found a multiport rs485 board (i think Industrial computer source sells some of these) and done the whole thing with a network of 68hc11's (actually you can implement rs485 stuff on a bus which is really neat -- and next time I design this kind of stuff I'll keep that In mind). One of the major problems with the networked embedded design was analog ports, I have 48 12 bit analog ports and I could not find any embedded hardware capable of sampling 256 ports at that resolution (also 10,000 samples/second) , so I am using a analog io card in a remotely connected machine, plus the processing overhead for the kind of operations being done are somewhat significant. But a remotely connected freebsd machine on ethernet can easily get that stuff apart and I am using xntpd to sync all the machines and put timestamps on the stuff --- sorry about the run on sentences I have written that way since I was 8 years old in really long sentences without periods or punctuation I guess just wanted to be rebellious because all of that private catholic schooling my mother put me through where they taught you every little detail of the english language complete with sentence structure diagrams in 6th grade which I don't think a lot of people in this sorry country don't learn until college (did you ever do sentence structure diagrams) when I was a little kid I knew all the names of word types and what they meant --- now I can only remember their names and write proper sentences (which none of this is) because I have seen it so many times before not because I understand what the hell I am doing at all, isn't it terrible when you don't think about what you do but rather just do it like a little robot, eh? In other words I needed a little more power than I could of gotten out of some embedded hc11 system for what I am doing > > mike > > >
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