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Thread: DMX for home lighting

  1. #1
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    Default DMX for home lighting

    Following on from my thoughts in this thread I've been googling and found a couple of older threads on this forum -

    This one and this one

    The criticisms mainly seem to be around the reliance on a live bus signal (rather than having distributed 'smarts' in individual switches/relays etc). That would seem to be a valid criticism for the Loxone system in general however, rather than being specific to use of DMX. Is there any further analysis anyone has done?

    DMX by itself isn't a solution of course - you need something to control it - but using Loxone for intelligence and generic, low cost, DMX switches and dimmers looks like it would be very cost effective

  2. #2
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    I used to work in theatre's and clubs as a technician mostly lampie with some sound, so I'm very familiar with DMX (it's currently an ageing industry standard for lighting control). I've not come across DMX in the home, but I suppose in theory it would work, but there's some reasons why I'd think it unsuitable.

    The main reason would be that DMX can only, and only designed to, work from one controller (There are times in the industry where this is not strictly true, usually involving 'sub-mixing' it can get quite messy). I suspect there are solutions which involve several units that all talk back to one main controller, but if this is the case it would seem more appropriate to go with a centralised HA system.

    DMX is designed to be always sending data, and it will be doing this regardless of whether the light is on or not. It doesn't just send the command and then be done with it, it is constantly sending out 512 values (ranging from 0-255 for each). Unless you require a lot of changes and are planning on hosting a rock show or dance floor lighting then it's a bit of an overkill.

    One thing I've found in my time is that you certainly get what you pay for in terms of DMX, you've mentioned cheap, but I'm sure you will have seen the other side of this also. The cheap dimmers will be fairly unreliable and will produce poor dimming ramps (I don't know if this would irritate you, but it certainly would me). Obviously this more noticeable on stage where there is more importance on the quality, but it's worth mentioning.

    Also, and I think this is the biggest issue, DMX is a protocol designed for daisy-chaining, which is fantastic for it's original purposes as on a stage lights are usually in proximity to each other and a star type topology would be a ball ache. For the home though, maybe not so good. It also introduces more opportunity for failure. However, I guess that in a house set-up you'd possibly run a separate DMX line per fixture.

    Just my two pence. As I say, I've not seen it in the home and my experience is with many hours of putting together and taking apart DMX systems as well as using them in high pressure situations in front of hundreds of people at a time.

  3. #3
    Automated Home Jr Member philipp.schuster's Avatar
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    Hi b33k34,

    there are a few points here that biccies makes that I agree with a few I disagree with.

    DMX has been used for years in homes, specially since RGB LEDs have found their way into domestic lighting. Before working for Loxone I designed and fitted home automation systems for 4 years and we have been using DMX the whole time.

    The main reason would be that DMX can only, and only designed to, work from one controller (There are times in the industry where this is not strictly true, usually involving 'sub-mixing' it can get quite messy). I suspect there are solutions which involve several units that all talk back to one main controller, but if this is the case it would seem more appropriate to go with a centralised HA system.
    Absolutely correct. DMX has one "Master" in our case the Loxone DMX Extension and then "Slaves" in this case Dimmer packs, LED drivers, etc. I don't see this as any disadvantage though... You can have 2 DMX Extensions and split your house to have 2 separate "DMX Universes" if you like. In my own house I use 36 DMX channels and never had a problem. If anything the simple nature of DMX, i.e. not needing CSMA/CD or similar makes it robust and predictable.

    DMX is designed to be always sending data, and it will be doing this regardless of whether the light is on or not. It doesn't just send the command and then be done with it, it is constantly sending out 512 values (ranging from 0-255 for each). Unless you require a lot of changes and are planning on hosting a rock show or dance floor lighting then it's a bit of an overkill.
    Again I do not see why this is a disadvantage. Just because you do not need it does not make it a disadvantage. Since DMX is simple the components are cheap so why not? You may install a Wireless N router yet only use the wireless G on it, this does not make it a bad choice, unless you have paid a premium for a feature you are not using.

    One thing I've found in my time is that you certainly get what you pay for in terms of DMX, you've mentioned cheap, but I'm sure you will have seen the other side of this also. The cheap dimmers will be fairly unreliable and will produce poor dimming ramps (I don't know if this would irritate you, but it certainly would me). Obviously this more noticeable on stage where there is more importance on the quality, but it's worth mentioning.
    I tend to agree with this statement "You get what you pay for". I have got a graveyard of cheap 230V DMX dimmer packs at home. The main reasons:
    • Burnt out triacs when GU10's blow
    • Flicker at low light levels
    • Minimum loads per channel too high for individual bulbs
    • Noisy when dimming

    That said I have never had any issues with DMX LED drivers.
    The dimming curves were never an issue for me as I could configure them in the DMX Master. In Loxone you can enable perception correction for lighting channels, which results in an exponential light level curve, to match the human eye's perception of light and you can also enter custom linear mappings.

    Also, and I think this is the biggest issue, DMX is a protocol designed for daisy-chaining, which is fantastic for it's original purposes as on a stage lights are usually in proximity to each other and a star type topology would be a ball ache. For the home though, maybe not so good. It also introduces more opportunity for failure. However, I guess that in a house set-up you'd possibly run a separate DMX line per fixture.
    Over short distances a star network works, but I cannot recommend it as it introduces an unnecessary risk by no adhering to specifications. You can however use a single Cat5 cable to send a DMX signal from Ground Zero to an LED controller and then using a different pair in the same Cat5 cable back to Ground Zero. Hence star wired Cat 5 architecture can be used to implement a BUS topology for DMX. The same applies for any RS485 based protocol and also 1-wire.

    Hope this helps.
    Home Automation Enthusiast and Head of Loxone in the UK.

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  4. #4
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    Quote Originally Posted by philipp.schuster View Post
    Hi b33k34,

    I tend to agree with this statement "You get what you pay for". I have got a graveyard of cheap 230V DMX dimmer packs at home. The main reasons:
    That said I have never had any issues with DMX LED drivers.

    Over short distances a star network works, but I cannot recommend it as it introduces an unnecessary risk by no adhering to specifications. You can however use a single Cat5 cable to send a DMX signal from Ground Zero to an LED controller and then using a different pair in the same Cat5 cable back to Ground Zero. Hence star wired Cat 5 architecture can be used to implement a BUS topology for DMX. The same applies for any RS485 based protocol and also 1-wire.

    Hope this helps.
    Yes thanks - that's great. I'm planning on being near 100% LED through the house so DMX and LED drivers looks like it makes a lot of sense - running just white LEDs it will allow me to sub-divide circuits further than I would have done otherwise and fine tune the dim levels.

    I'd thought about that star pattern - good to know there aren't any issues i'd not spotted. I presume total cable run length is rarely a problem in residential, especially in a new build where the runs can be properly planned.

  5. #5
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    DMX controls are often used in offices and Bars. This controller is something I have always liked but its a bit pricey considering it just controls lights. Its just under 600 pounds.
    I have often wondered why DMX based lighting hasn't been more popular in the home.
    IF YOU CAN'T FIX IT WITH A HAMMER, YOU'VE GOT AN ELECTRICAL PROBLEM.
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  6. #6
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    An old post, I know. But I was interested in Philipp's comment;

    Quote Originally Posted by philipp.schuster View Post
    I have got a graveyard of cheap 230V DMX dimmer packs at home
    @Philipp Really interested in knowing more about the ones you tried!

    Not many people review DMX dimmer packs from a HA point of view. Did you settle on a model / make?

    I'm looking for 30 channels of light control (a couple for switching but mostly a mix of leading edge dimming and PWM dimming for LED, etc.)

    What are the best options? (Would rather go cheap and manually replace triacs when they blow than spend a huge fortune...)

    Thanks!

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