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Thread: DMX for Home Automation

  1. #1
    Moderator toscal's Avatar
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    Default DMX for Home Automation

    I've often wondered why the DMX protocol has never really made it to the domestic market. Anyone have any ideas as to why.
    The only article I have seen, about using it in the home, was published here in Automated Home. http://www.automatedhome.co.uk/Tutor...ng-System.html
    I did think it was because of the lack of controllers but apart from the large mixing desk type there are small PC interfaces and wall mounted ones. Some of the wall mounted ones though do look like they where knocked up at home from the plans in an electronics mag published in the 70's.
    I have seen rather nice wall mounted controllers that wouldn't look out of place in a home. have a look here http://www.mr-resistor.co.uk/item.as...6&r=758&i=6576
    I know its only one way communication so no verification that the light is actually on.
    But I have always wondered why its mainly only used in commercial lighting systems and for concert or theatre lighting. It does seem quite a robust system after all if you are doing a gig you don't won't the fog machine to come on at the wrong time or the flashy lights to suddenly have a mind of its own.
    Any one have any thoughts or ideas.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
    www.casatech.eu Renovation Spain Blog

  2. #2
    Automated Home Jr Member nickgale's Avatar
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    Default

    Having worked in the theatre lighting industry for far too many years before starting my own company installing home automation I hope I have a good understanding of both?!

    DMX is a way of transmitting 0-255 or 0-100% over a twisted pair and screen to up to 512 dimmer channels, these channels could be dimmers, movement, colour, etc..... But it is simply a value transmitted sequencially 0-255 for each of the 512 chanels, one after the other. For an entertainment lighting system this is great, you have a single controller - a lighting desk and a number of dimmers or moving lights all part of the same show / stage. We don't need to worry about areas, rooms, etc. as the whole show is a single entity. But not only is this a single area system it also needs a constant stream of channel information, even if nothing has changed in the last 2 seconds it will continue to send channel levels for all 512 channels one after the other.

    Home automation as well as commercial lighting schemes need to treat areas differently, a lighting scheme may well have say 20 rooms or areas all needing different scenes, triggered by different panels maybe at the same time. For this a system like KNX, Dynalite, etc. is ideal as you can split the system into areas and then send a command that says area 4 go to preset 6 in 5 secs. this is generally a command that is sent only once over the bus, and the dimmers that are programmed to respond do so, so a simple message or telegram causes the change to happen.

    Basically DMX is a single human interface system, home automation and commercial lighitng schemes need multiple human interfaces. Think of it as this, if you had a house with 10 rooms, each with 3 lighting circuits per room you need 10 different 'controllers', 10 different DMX lines and 10 x 3 channel dimmers, and then you'd have a real headache trying to work out how you do a house all off!

    DMX is great, have installed many systems with several universes (512 channels per universe) in entertainment venues. Would I use it in my home.... NO!

    Cheers

    Nick

  3. #3
    Moderator toscal's Avatar
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    Default

    Many thanks for that.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
    www.casatech.eu Renovation Spain Blog

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