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D.I.Y DMX PC Parallel output dongle.

Discussion in 'Lighting and Electrics' started by Stong, Mar 18, 2004.

  1. Stong

    Stong Member

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    After much deliberation, I've come to the conclusion that the easiest way for me to control 3 mac 500e's from on stage is to use my laptop with some sort of dongle to output DMX. I'm giving a workshop on moving lights, and I'm currently stranded in red deer. I highly douby my ability to make it into a major city to find a dongle that will do what I want it to, and even if I do I'm not sure I want to pay the price.

    I'm looking primarily at the Win Commander style dongle from Audio Visual Lighting (http://www.xs4all.be/avl/wincommander.htm) since it seems to lack any extra electronics and is straight from printer port. This makes life easy for me, it's just a matter of figuring out what pins on the printer port provide the 3 DMX lines I need. I've started searching for a DIY project on the net, but haven't had too much luck so far. If anyone has accomplished something like this or knows of a good resource that would assist me in making one, I would love to hear about it!
    Thanks in advance.
     
  2. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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    I think it is somewhat more complicated than that as I am sure that your laptop lacks the DMX output chip and other smarts that are required.

    DMXtools is a guru when it comes to DMX and we are fortunate enough to be a very active member of this board. I am sure that he will drop by an shed much more light on the matter than I have (or can).
     
  3. Mayhem

    Mayhem Senior Team Emeritus Premium Member

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  4. Stong

    Stong Member

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    yeah. I had read through that already. I found and looked at some schematics for a parallel DMX out and it's not as simple as I thought, but it's entirely possible for me to do, even in Red Deer.

    http://users.skynet.be/kristofnys/images/picdmx.jpg

    Doable. Only 64 channels, but that's plenty enough for me! I'll only need 52 max. Just hope the software works :)

    He has a link on his page to a better, more stable version which aparently (with a different circuit) does 256 DMX channels, but the link results in a gateway error.

    I should point out that I thought that it was possible to control the pins of a printer port to the point of the biggest obstacle in creating a DMX signal was the programming - DMX standard is something like 250kbps, which is far below the max of parallel (although I'm not sure if that's changed by the number of pins) and I'm almost certain parallel could vary from +12v to -7v relative to a ground.... Anyone have knowledge to share?

    It earlier occured to me that it would also be possible to run 75 feet of RJ-45 up to the ethernet switch between the expression and the emphasis server, and use that to set up remote control of the emphasis server, which would in turn allow me to control the board remotely through WYSIWYG...

    I'm going to spill some of this over into a new topic..
     
  5. DMXtools

    DMXtools Active Member

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    Your 75' of Cat. 5 cable seems, to me, to be a pretty sensible approach. I can coax a little 8031-family microcontroller into building DMX packets and spitting them out the chip's serial port, but I don't have the PC Software experience to coax a parallel port into doing the same. For me, the ability to use existing, proven software (WYSIWYG) on the PC would be a huge plus. And cat 5 cable is probably no more expensive than the parts needed to build a dongle that may or may not work the way you want.

    John
     

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