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Thread: A bit of 1-wire wire help please.

  1. #11
    Automated Home Sr Member Quinten's Avatar
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    May 2004
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    I got mine made by a member on the ukha_d yahoo group/#ukha irc group called Stuart/Gadget. Pretty sure he's a member on the forums too.

    My 1wire network consists of one long chain of modules, going from the center of the garage (where my node0 lives) through the outside wall, into the bathroom (hard to explain, but it's the easiest way to get cables up in the loft), through the airing cupboard in the middle of the house, into the loft and then from room to room. All in all, I think it's about 30-50m of cat5 cable. And although I'm still running in parasitic power mode, I've yet to experience any problems with sensors falling of the network. It is surprisingly reliable!

    Future plans involve a sensor in the living room and kitch, but they aren't easy to reach without major refurbishment

  2. #12
    Automated Home Jr Member
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    Feb 2004
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    Timely discussion as I've just re-run my own 1-wire network. Previously I had a bit of a mix of cables (though all cat 5e) and the odd long stub where I'd decided to add an extra sensor later. Although it worked It did suffer from the odd sensor going missing and slow updates sometimes.

    I've replaced all the existing cabling with a new run of Cat 5e that loops in and out of each sensor location. I decided to go external powered due partly to the number of sensors (25) and partly to future proof it in case I decide to add any devices that require power. It's not actually powered at the moment but the option is there.

    I see you can get pre made modules from ebay (http://cgi.ebay.co.uk/SWE1-DS18S20-T...item1e5e1cd2f7)

    I took a slightly different route that's a bit more heath Robinson - I didn't fancy terminating each cable in a RJ45 plug twice at each location so I used keystone RJ45 sockets, double punched with the 'In' and 'Out' cables, heat shrinked and cable tied to provide some mechanical support. I know double punching IDC connectors is frowned upon but in my experience, as long as the cables are identical, you can get away with 2. I then soldered the temp sensors onto a short length of premade patch cable (about 1") protoected with a bit of heat shrink. These then simply plug into the keystone sockets and are housed in the same enclosures as earlier in the thread - I got mine from CPC and sprayed them white to match the ceilings.

    Got all the 1-wire parts from Hobby Boards who I would recommend:
    http://www.hobby-boards.com/catalog/main_page.php

    Nice guide from Maxim on long networks and loads:
    http://www.maxim-ic.com/app-notes/index.mvp/id/148

    Cheers
    Kevin W.

  3. #13
    Automated Home Jr Member Simon300's Avatar
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    Apr 2010
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    Thanks Quentin & Kevin W for your updates. It's nice to hear that 1-wire can be very reliable - sometimes it's easy to get bogged down reading about problems.

    I like Kevin's idea for just using one RJ45 socket per junction - the 1-wire cabling is fixed and the socket is only allowing for easy sensor installation/replacement so 3 sockets could be overkill. I don't suppose there's much to worry about from having two cores installed in one slot - the blades are parallel for a mm or two anyway. Plus if I go for this idea of having pins 4-5 going to the sensor and 6-3 coming back the only pin doubled up would be 2/Vdd (unless I looped through 1 and 7 & 8 - I can't really see the need at the moment though).

    BTW: I've got my eye on http://www.hobby-boards.com/catalog/...oducts_id=1554 so will probably get one shipped over from the US. Thanks for the recommendation.

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