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Simple DMX question

Discussion in 'Lighting and Electrics' started by ishboo, Jul 19, 2008.

  1. ishboo

    ishboo Active Member

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    SO this should be a quick and easy question.
    My school is doing our fall musical in our old theatre with dimmers that are a good 20+years old. They run on some form of DMX, I'm pretty sure it isn't DMX-512. Our light board that goes with it is in pretty bad shape. Is it possible to use a DMX-512 compatible board on an older version of DMX (I'm pretty sure you can't but it is worth asking).
     
  2. waynehoskins

    waynehoskins Active Member

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    There is no predecessor to DMX512. There are successors, which would be the 1990 and recent revisions to it (DMX512-1990 and DMX512-A, I believe), but these made no major changes to the core of the protocol as it's used; they chiefly addressed some ambiguities of other aspects like the second data link that nobody can agree how to use if at all.

    What's the board? It's quite probably a multiplex protocol that's not DMX. Possibly AMX192, the standard that came out a few years before DMX? If not, it's probably a manufacturer-specific protocol (which DMX and AMX standards were developed to replace, being an industry standard rather than brand-specific).

    Teatronics had T-Mux.
    Strand had CD80 (which became AMX) in the US and D54 in Europe.
    Colortran had Colortran Protocol, later renamed CMX (which effectively became DMX).
    Kliegl had K96.
    NSI has Microplex, which continues still.
    Lightronics and Leprecon have their muxes.

    With the make and model of the board and rack (and maybe a description of the connector) we can make a good guess.
     
  3. ishboo

    ishboo Active Member

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    I don't know the name of the board off the top of my head, but the plug is a 5-pin at least dmx style and I'm 95% sure the plug on the board says DMX. The next time I'm at school I get a picture of the board. My teacher said that its an old version of DMX and not DMX 512 compatible but he could be wrong. If it says DMX would it be DMX-512.
     
  4. Clifford

    Clifford Active Member

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    Yes, it would be the same. As waynehoskins said, there wasn't an "earlier DMX", although there have been variations. DMX has always controlled 512 dimmers/channels/attributes. As long as it is DMX, and you don't try to get mixed up in second data links, compatibility shouldn't be a problem.
     
  5. Grog12

    Grog12 CBMod CB Mods Premium Member

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    Let us know what kind of dimmers you have as well.
     
  6. ishboo

    ishboo Active Member

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    I should be in there in a week or two and I'll write everything down and I'll test it with my DMX board and let you know. Thanks for all the help!
     
  7. dramatech

    dramatech Well-Known Member

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    Not all DMX is compatible with each other. A number of years ago, I was doing a hang in an ampitheater at Busch Gardens (Williamsburg). This particular theater gets all of the stuff that is left over from the the other venues in the park. We had dimmer racks that were ETC sensor, Strand CD80 packs modified to DMX with Lightronics drivers, LMI 48 channel and some unknown brand that was Analog with an ETC Response unit. There was also 12 Wybron Forerunners. The board was a Strand LP90. The DMX was a continuous daisy chain. Bottom line, the scrollers and the LMI rack went crazy and wouldn't follow correctly. After a few well placed calls to knowlegeable folks, we were directed to Doug Fleenor. DR. DMX immediatly identified the problem as the board was the original DMX of 1986, and several of the pieces of equipment wanted the 1990 version or later. He overnighted to us one of his combiners. We used just one of the inputs, and everthing was just as happy as it could be.
    Lesson learned, the older 1986 DMX is not compatible with all DMX receiving equipment.
    There is a cheaper way to accomplish the same thing as the Doug Fleenor device. Northlight systems sells a Eight channel encoder with DMX merge for about $100. It is just the circuitboard complete, and will require connectors and a power supply. It must be the one with merge as he also sells an encoder without merge for about $50. Just plug your old DMX board into the merge input and use the DMX out from the Northlight circuit and it will be DMX USITT 1990. Northlight Systems can be found with a google search. They are in Tempe AZ. The guy who owns it is James Cart and he will answer any questions you have, and will many times make some modifications for nothing.
     
  8. TimMiller

    TimMiller Well-Known Member

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    Dimmers do not usually care about how old the console is (yet some do, i have run into this in some old nsi dimmers). But things like scrollers and moving lights due. It has to do with the timing of the dmx signal (if you notice on many of the ETC consoles you can actually change the dmx speed to fix this problem). With the dimmers I was having issues with, every time i brought up a channel they would all blink.
     
  9. Darthrob13

    Darthrob13 Active Member

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    Also remember our industry loosely interprets what a "standard" is.

    Hog DMX is different from Obsession DMX which is different from 520i DMX.

    It's maddening sometimes.
     
  10. dramatech

    dramatech Well-Known Member

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    Most differences in DMX, from various manufactures after the 1990 staandard was established, is the refresh rate. DMX is a serial protocal, that means that in the time domain information is sent out in serial fashion, such as look at the digital information for dimmer channel 1 then 2 and on and on until we reach 512 and then start over again. If this is done too slowly, as a light dims, it will appear to do it in steps. If the rate is too fast, some pieces of equipment will actually miss some of the information. The DMX standard allows for different rates. Some console manufactures provide a method in the setup menu to change that rate. Others don't. Some do it automatically by you telling the maximum number of dimmers you will be addressing.
     
  11. ishboo

    ishboo Active Member

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    Sure enough! The dimmers take DMX-512 we wheeled our board down there today and gave it a whirl. Thanks everyone!
     

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