Re: 1-wire network layout?

["dermot_bradley" <bradley@xxxxxxxxxxxxxxxxxxxxx>]

--- In ukha_d@xxxxxxx, Kevin Hawkins <yahoogroupskh@...> wrote:
>
> Although some devices eg temp sensors only require two connections
> (parasitic power) some others  require three - and the two wire
> devices can operate in the three wire mode (ground, power and data).
> My '1-wire' network didn't work well as a two wire but works great
> with three wires. Your 4 core cable will cater for this but as a
> precaution I wouldn't run just two core anywhere , just in case.

I've ended up running a single segment between all 3 floors using
approx. 80m of 4-core telephone cable.

I also now have a DS9490R USB-to-6pin RJ11/12 master and several
DS18B20 temperature sensors to wire up.

According to their specs sheets, the DS9490R has the following pin
arrangements:

1: Vdd,    5VDC output
2: GND,    Power ground
3: OW,     1-wire data
4: GND_OW, 1-wire ground
5: SUSO,   USB suspend output
6: N/C     no connection

and the DS18B20 has 3 pins:

1: GND, Ground
2: DQ,  Data In/Out
3: Vdd, power supply voltage

Now I don't want to use parasitic power but I'm not entirely sure how
to wire things up. I'm guessing I should I do this:

pin 1 (GND) of temperature sensor to pin 4 of USB interface
pin 2 (DQ) of temperature sensor to pin 3 of USB interface
pin 3 (Vdd) of temperature sensor to pin 1 of USB interface.

and then leave the 4-wire of the 4-core cable unconnected to anything.

To stick with wiring standards I guess I should use blue wire for DQ,
blue-white for GND, and not sure which colour to use for Vdd.

Can anyone comment on this?



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