I've put the Eagle files and some pictures of the 16 bus master and hub
here:
http://www.brain4home.eu/index.php?option=com_content&view=article&id=48:16-chanel-board-and-hub
pascal
2011/9/18 Eloy Paris <pe...@chapus.net>
> brucek <bru...@valinet.com> wrote:
>
> >If you have an extra pair in the wiring, you could use one pair in and
> >one
> >pair out so that the star is functionally a liner network
> >bk
> >
> >-----Original Message-----
> >From: ekgnkb3d
> >Sent: Saturday, September 17, 2011 7:05 PM
> >To: owfs-developers@lists.sourceforge.net
> >Subject: [Owfs-developers] increase OW reliability in bad topology
> >
> >
> >Hi all,
> >my problem is a little bit off-topic (because not specific to owfs),
> >but
> >maybe in this forum are the experienced 1-Wire net experts ;-)
> >
> >I want to replace in an existing building the 12 analog temperature
> >sensors
> >by 1-Wire DS18B20 temp sensors. The used cables are standard telephone
> >twisted pair which are shielded together. They are in star-topology, so
> >each
> >of the 12 cable come from a different room (10m to 50m length each) to
> >the
> >central controller. So the complete net have a "weight" of approx 350m.
> >The cables shall be reused, because it would be a hell a lot of effort
> >to
> >replace them too.
> >
> >As mentioned in http://www.maxim-ic.com/app-notes/index.mvp/id/148
> >Maxims
> >application note 148 and
> >
> http://docs.google.com/viewer?url=http%3A%2F%2Fwww.1wire.org%2FFiles%2FArticles%2F1-Wire-Design%2520Guide%2520v1.0.pdf
> >1-Wire.org Design Guides , the star is the most critical topology for
> >1-Wire
> >nets. But what can I do, especially with OWFS, to increase the
> >reliability
> >of such a net? I've thought of the following already:
> >
> >- Using active pull-up bus masters, e.g. DS2482 with FET
> >- If using 4 bus-masters, each one have to drive 3 sensors only and
> >therefore reduce the weight to approx. 100m each.
> >- Slowing down the net to 16kBit/s Standard Mode (how to do this on
> >DS2482
> >with OWFS?)
> >or even go slower down, to 8 or 4 kBit/s?? (The temperature is only
> >needed
> >each minute)
> >- Problems usually look like the devices are lost, the search algorithm
> >occasionally can't find some devices.
> > Is there a way to configure OWFS to retry let's say 100 times until it
> >really gives up?
> >- Connecting each DS18B20 with 3 wires (+5V and 100nF Capacitor each)
> >- Ensuring that the GND and OW-Data wire is a twisted pair of the cable
> >- No termination resistor at the end of the cables
> >
> >any more constructive ideas?
> >
> >Thanks
> > Achim
> >
> >--
> >View this message in context:
> >
> http://old.nabble.com/increase-OW-reliability-in-bad-topology-tp32487173p32487173.html
> >Sent from the OWFS - Dev mailing list archive at Nabble.com.
> >
> >
>
> >------------------------------------------------------------------------------
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> >
> >
>
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>
> +1
>
> That is what I do in my house, where I have structured wiring. Currently
> have 12 ds18b20. Have not had a problem. I use parasitic power. Just make
> sure you do not leave Vdd floating (ground it).
>
> Cheers!
>
> --
>
> Eloy Paris
>
>
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>
--
Pascal
www.brain4home.eu
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