Re: [DIY-Zoning-general] DZ temperature sensor HOWTO

[David C. <da...@ca...>]

Now it's obvious! The Step 2 picture makes this distinction, I just didn't
grok it before.

Thanks for clarifying.

Regards,
David

---
David Carter
da...@ca...


On Wed, Jul 7, 2010 at 10:55 PM, Vadim Tkachenko
<vt...@fr...>wrote:

> Hello David,
>
> > Shouldn't the 1-wire signal & return (ground) should be on a single
> twisted pair,
>
> They are :)
>
> > not on two different twisted pairs?
>
> They are not :)
>
> > My (admittedly limited)
> > understanding of twisted pair is that having the signal & return on the
> same
> > pair is important to reducing cross-talk, etc. Please feel free to
> correct
> > me if I've misinterpreted something?
>
> Yes, the pictures make it difficult.
>
> > The hobbyboards diagram shows the 1-wire signal & return on the same pair
> (blue & blue/white).
>
> 1-Wire in goes just like HobbyBoards - blue + blue/white. However, in
> order to daisy chain multiple sensors on different Ethernet cables
> coming to the same patch panel without creating the star topology and
> keep it as a bus, a return was introduced - green + green/white.
> Punchdown block wires multiple segments of cable together, thus you
> have a physical star and electrical bus configuration. Granted, the
> effective length doubles (and it would be a good idea to either
> terminate the last sensor or not connect green + green/white), but
> alas, so far so good, it works.
>
> > -David
>
> --vt
>
>
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