Subject:
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RE: Have you guys seen Meccano's "RCX" ?
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 31 Oct 2003 20:34:55 GMT
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Reply-To:
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<[rhempel@bmts.]stopspammers[com]>
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Viewed:
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971 times
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> > The one thing missing from my initial reading of DCC is the lack of two way comms
> > except through the acknowledge bit. Perhaps this could be extended...
>
> In fact, NMRA has a proposal on the table which specifies how DCC decoders can
> talk back to the command station. The decoder basicly sends a reply in between
> DCC packets (during which time track power is removed) using a current loop at
> 125 Kbps. Check out RP-9.3.1 and RP-9.3.2 on the following page:
>
> http://www.tttrains.com/nmradcc/draftstandardsandrps.html
Cool!
In the fire alarm trade (I design firmware for these systems) there is
a need for communications on a single pair of wires with up to 256 devices.
Sound familiar?
What we do is hold the line steady and the device applies load across the line so the
loop controller can measure current pulses to decode information from things
like smoke detectors and control relays.
Sound familiar?
I worked on one system designed so that the devices could see current pulses from
other devices further down the line. We developed an auto-addressing algorithm
that took care of problems like swapping out sensor 23 with a new sensor with a
different address.
Sound familiar?
What I'm getting at is that there is a big parallel between what we want our
LEGO control system to do and what real-world low-power systems do.
For me, the biggest thing is to be able to supply power and data on one pair of wires.
Sure, the throughput suffers when you add more devices. So split it up into a
couple of pairs of wires.
Having playd with DCC integration in the basic RCX, I'm convinced that DCC holds
a part of the key that unlocks low cost controls for our creations. After all
the train hobbyists and us do share some goals as well...
Ralph
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Message is in Reply To:
 | | Re: Have you guys seen Meccano's "RCX" ?
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| (...) [snip] (...) In fact, NMRA has a proposal on the table which specifies how DCC decoders can talk back to the command station. The decoder basicly sends a reply in between DCC packets (during which time track power is removed) using a current (...) (21 years ago, 31-Oct-03, to lugnet.robotics)
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