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n00b question: DMX Termination

Discussion in 'Lighting and Electrics' started by PhantomD, Sep 23, 2006.

  1. PhantomD

    PhantomD

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    In what situations does DMX need to be terminated?

    We are currently running 3 DMX dimmers in series, as far as I can see it's non-terminated.
     
  2. Chris15

    Chris15 CBMod CB Mods Premium Member

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    I'm certain this has come up before. Did a search yield no results?
     
  3. PhantomD

    PhantomD

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    We don't need the attitude matey.

    There are no threads specifically on DMX termination, and I am not going to go through each one specifically.

    Now is there anybody who actually has something they could contribute, please?
     
  4. CURLS

    CURLS Member

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    Yes, we have covered this question in this http://www.controlbooth.com/forums/showthread.php?t=3283 forum very extensively.

    Most dimmers terminate at the end of a series or daisy chained connection anyways but if they dont put a xlr at the end with a simple 120 Ohm resistor between pins 2 and 3.
    But, to really answer the question dmx should be terminated at the end of all daisy chains whether it be dimmers fixtures color changers. fart i mean fog machines. Well you get the picture and refer to the previous forum as to why. Or just type "DMX TERMINATION" in google thats how I tought myself a lot of stuff!

    Hopes this helps!

    I am now no longer hungry b/c i just SuPeER GRAND SLAMMED MY ASS AT DENNY"S!!!
     
    Last edited: Sep 23, 2006
  5. Chris15

    Chris15 CBMod CB Mods Premium Member

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    I know that I am not alone in getting rather annoyed when the same thing gets covered in more than one thread. It means that when I want to know something that I have to trawl through umpteen different threads to have a chance at finding what I am after. You said that you did not want to read through all the threads. I don't either and as far as I am concerned, this thread just adds another one to the list of threads I have to check if I'm after info on DMX.

    I think the consensus reached was that if it is working fine without a terminator then it will likely continue to do so. If there are problems, try using a terminator and see if that fixes them.

    It is not that I have a problem with you, it is that you have hit my pet hate, multiple threads asking the same question. We might both be Aussies, but that does not automatically make me your mate.
     
  6. PhantomD

    PhantomD

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    Thanks, I'll stick with the "If it ain't broke don't fix it" rule mentioned in that thread.

    Because there is no termination and it is working fine.
     
  7. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Did not someone also say that in some cases, it even works better without termination? I'd be sticking to the it ain't broke so don't fix it unless you start to have the dimmers going haywire.
     
  8. jonhirsh

    jonhirsh Active Member

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    Dont go all blue room on me guys, their is a reason i had them delet my acct on there.

    JH
     
  9. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Could you please explain what you mean by that?
     
  10. jonhirsh

    jonhirsh Active Member

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    The blue room is another technical forum that has a reputation for being crass and snarky towards members who do not use the search feature.
    http://www.blue-room.org.uk/

    and that is the reason i do not feel a need to involve my self with them any more. An simple hey did you use the search feature would be enough.
    JH
     
  11. Chris15

    Chris15 CBMod CB Mods Premium Member

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    I had heard of them, didn't know they got so thingy over search.

    I shall try to keep these comments in mind.
     
  12. Van

    Van CBMod CB Mods Premium Member

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    Back to the real point. DMX chains should always be terminated. period. all it takes is a the addition of one wrong length of cable and you will develope a standing wave that will play hell with your dims, moving lights whatever you might have plaugged into the DMX Stream. Most decent dims and fixtures have terminator options built into them if they don't then, as mentioned earlier it's extrememly easy to build a terminator.
     
  13. Chris15

    Chris15 CBMod CB Mods Premium Member

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    I am CERTAIN that there were reports in one of the previous posts that their systems worked fine without a terminator but played up when there was a terminator. I say he old saying should hold here that if it ain't broke, don't fix it.
     
  14. PhantomD

    PhantomD

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  15. Van

    Van CBMod CB Mods Premium Member

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    Chris Not pulling rank, nor can I refute anecdotal evidence that a system acted up after being terminated. I can say that According to my training as a feild tech for E.T., and as per my conversations with Gordon Pearlman, DMX if conforming to the international specifications for DMX512 must be terminated period. If a system were to act up after being PROPERLY terminated then I can only assume there is a reflective situation occuring somewhere prior to the termination and that it would have shown up eventually. Speaking from personal expirience I have NEVER known a properly installed system to have had its integrity degraded by being PROPERLY terminated. The old saying If it ain't broke don't fix it works great in a mechanized society. I think in the digital world I would prefer one ounce of prevention is worth a pound of cure
     
  16. Chris15

    Chris15 CBMod CB Mods Premium Member

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    I am tending to agree with you Van. In this digital world we can't make the same assumptions as with analog and mechanical systems. Digital systems have much more of a tendency to fail without apparent reason.

    Would you think it possible that multiple terminations could be causing such alleged problems? I don't know anything about it, but it does sound plausible.
     
  17. jonhirsh

    jonhirsh Active Member

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    Did you ever consider that you had a bad terminator?

    JH
     
  18. Chris15

    Chris15 CBMod CB Mods Premium Member

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    Hey, I am only going on what was said previously in other threads. I haven't used DMX enough to base anything on past experience. For all I know, anything could have been the cause. Lets' just say that you should terminate your DMX, but if there are problems, and unterminating the line fixes those, then do it temporarily until you can work out what caused the problem and fix it.
     
  19. Van

    Van CBMod CB Mods Premium Member

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    I would say that a bad Terminator < like Shcwarzeneger in the first movie> Could very well be the cause of illicit behavior. Poor solder connections, improper aplication of the drain wire, using the foil shield as a drain, and improperly built terminators can all lead to some of the wierdest behaviors I've ever seen.
    Apologizing for my earlier post, just came out of an extremely frustrating production meeting, must have had left over angst.
    New maxim, " Never go to bed angry with your partner, Never post on C.B. when your angry. Eat more Fiber."
     
  20. PhantomD

    PhantomD

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    Yes, a bad solder joint coming off the Phase A DC transformer in one of my dimmers recently caused it to drop Phase A whenever DMX was input. :rolleyes:

    :evil:
     

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