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How DMX works

Discussion in 'Lighting and Electrics' started by BestBrightLED, Aug 9, 2011.

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  1. BestBrightLED

    BestBrightLED BANNED USER

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    How does DMX Actually work? ​
    This article was originally called “DMX Stage Lighting Systems – Get Them To Talk” but, apart from being a bit of a lame title, this actually misses the point of the serial DMX signal. Unlike modern networks, DMX lighting fixtures and their controller do not all “talk” to each other.



    When a DMX Lighting Control starts – everybody listens!​
    Information about each “DMX Channel” (in the old days, a dimmer number) and it’s level (0 – 100%) is transmitted down the DMX “Universe” cable and each DMX stage lighting fixture, moving light or smoke machine listens for it’s own part of the signal stream and ignores everything else. The signal is then transmitted over and over in “packets”, giving a regularly updated stream for the rig to obey. The lighting console receives no information in this one-way street.
    In order for all the DMX stage lighting fixtures to have their own part of the signal stream, each one has it’s own “address” which is set on the fixture using buttons or switches. If a dimmer channel has a DMX address of 001 then it listens for the 001 part of the DMX signal then obeys the “channel level” value, 75% for instance.
    Once all intelligent lighting fixtures, dimmers and accessories are connected up and “addressed” the lighting desk can control each part of the rig individually using their own unique DMX address.


    The DMX Universe​
    Back when we only controlled dimmers using DMX, life was simple. 1 DMX Channel = 1 Dimmer No. Then we started to use more complicated fixtures, moving lights and intelligent (?) lighting that needed more than 1 DMX channel per fixture. This means that fixtures are assigned a DMX “start address” which is the first channel in a sequential batch that the fixture listens to. If your fixture uses 6 DMX channels and you set it to a “start address” of 001 then it listens to channels 001,002,003,004,005 and 006. Your next free address for another fixture is then 007 because if you set it to 006 then the “channel overlap” would create a conflict of control. Setting fixtures to the same start address can be useful some circumstances and is a common method of DMX fault finding.
    With many DMX moving lights requiring the use of 20 or more channels, those 512 don’t look too many now, huh? A few moving lights, 100+ Dimmers, Strobes and a couple of smoke machines and you’ve run out of channels already! The solution to this problem is to connect and address some of your equipment on a second DMX “universe”, a different signal stream with even more cables. Many lighting control desks have more than one DMX output these days and the principles of fixture addresses and channel numbers apply to this, and subsequent, universes. The first DMX channel on a second universe is also 001 and each DMX universe is a totally separate stream, independent of each other.
    Last edited by a moderator: Aug 9, 2011
  2. xander

    xander Active Member

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    I'm not really sure what the point of this thread is. Is this a brochure or something that you want to include with your products and you are looking for feedback? Is this an article you or someone else wrote for some sort of publication? Are you asking if the information contained is accurate?

    -Tim
  3. mrb

    mrb Active Member

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    seems the point of the thread is to spam CB with his company

    if I was going to buy LED fixtures, i would buy them from Bill @ ESC Entertainment systems corporation as he is an active member of this forum who makes many contributions and has a solid track record.
  4. DuckJordan

    DuckJordan Well-Known Member

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    Lets make a few edits here, since there seems to be some mis-understanding in how DMX works.

    Oh, and I'm still waiting on the information about 'their' movers.
  5. xander

    xander Active Member

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    I was trying to be polite and not presume the worst. ;) If it was an attempt to sell products it was a very, very bad attempt.
  6. Les

    Les Well-Known Member Premium Member

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    I think everyone should ease up a little. OP didn't break any rules in his post, so there's really no reason to go after him like this.
  7. chausman

    chausman Chase

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    I don't know what it's for, but could it be a useful addition (with the proper corrections) to the wiki article on DMX?
  8. DuckJordan

    DuckJordan Well-Known Member

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    No but this has been covered about 20 other times including in the wiki.
  9. chausman

    chausman Chase

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    While it has been covered quite a bit, someone learned something, just with the edits you made. If this was something that would going to be posted on their website, or printed in a catalog, it should have correct information, no?
  10. DuckJordan

    DuckJordan Well-Known Member

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    Which would have happened durring a search. The reason I'm irritated with it, is the fact I've asked for information regarding their moving head fixtures almost a month ago and have gotten absolutely no response. This is more of an issue since they seem to be mac 550 knock offs. I'd have no issue with this user posting information (by adding to an existing article or the wiki) that they may share or making a new post about a question or new information not readily accessible here on the forums.

    This has the look of a company who doesn't really care what they are doing on an educational forum other that to advertise themselves.
  11. BestBrightLED

    BestBrightLED BANNED USER

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    WOW is this really how you people are on here>???
    Doesn't anyone else here think lynch mob?.. LIKE REALLY ?? yea i own an led company i did something for myself? AND NO I'M NOT TRYING TO PROMOTE ON YOUR FORUM !!!!!!!!!! just trying to add insight.. and if its on my website... SO WHAT .. IT"S MY INFO. are you mad you learned something?????.. I don't understand you people .. i wanted to add something that i am knowledgeable in and you rip me a new a**hole??? does that sound normal??
  12. DuckJordan

    DuckJordan Well-Known Member

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    It wasn't the fact you own a company. It's the fact you haven't taken the time to check our already large amount of info on dmx. Not to mention the lack of discussion.. this is a forum and not a blog none of us meant any offense and we will be happy to try and make you feel less attacked... but look at it from our point. The two posts you made were both copy and paste articles that assumed that there was no information already prevalent. I'm sorry you felt attacked but we like to have discussions not pushed information and never actually learn something....



    Ps I am still interested in info about the movers you sell.

    Sent from my ADR6300 using Tapatalk
  13. gafftaper

    gafftaper Senior Team Senior Team

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    Thread closed.

    BestBrightLED, attempting to start a flame war will not be tolerated. Re-posting a flame message 5 minutes after it has been deleted by a moderator is not acceptable behavior. Private messages from other moderators have apparently not gotten through to you, perhaps a public message will. This is an educational forum, visited by hundreds of thousands of technicians every year from middle school students to top industry executives. All members are expected to act professional. I suggest you seriously reconsider the reputation you are creating in the industry by your posts here.
    Last edited: Aug 17, 2011
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