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Thread: DMX Plugin Question

  1. #11
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    More out of curiosity than anything else, what does that mean? It is surprising to me that there was any timing sensitivity at all, unless the Entecc controller is lacking in memory.

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    Phil

  2. #12
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    The Enttec device doesn't have any memory. For that dongle to work all the DMX packet information and timing needs is handled by the host PC. The Open DMX device is just a FTDI USB-to-Serial adapter connected to a RS485 transceiver (75176). Altering the plug-ins timing did cause issues, hence my hesitation for changing it. It’s the whole "leave well enough alone" thing.

    The DMX Pro on the other hand generates DMX from the onboard microcontroller. All the host PC has to do is send channel intensity updates as they happen.
    DMX, RDM, ArtNet, sACN, and RDMnet...the future of DIY Christmas.
    Designer of the PropController an open source single-board hardware platform designed for lighting and prop control.

  3. #13
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    Leaving well enough alone sounds like a good idea to me in that case. Not that anyone asked me.

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    Phil

  4. #14
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    Then I agree I believe we need to look at recommening the pro or something else. Unless ( and this is a possible I guess ) that I'm having my own issue with running it on this computer (3.2 gh) its just not as quick as I had hoped. Hence the request. I dont mind spending the extra as I am going all dmx but I wish we could offer a good cheap alternative to the rest of the DIY'ers. On the other side of it would you guys be willing to let me hack on a copy of the plugin as I can test the dmx and if I was able to do it and if it did what I am hoping we could use this cheap unit for the masses and have refresh rates they will be happy with on less than 512 channels and I dont think I can hurt my copy of vixen with a bad copy of a plug in. If I make it work I will send KC and Ben the modified version to test and distribute if they feel its ok. If I can't nothing but a little lost time on my side.

  5. #15
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    So the question that I still have is where does the need for a higher fresh rate come from? Are you seeing steppy dimming?
    DMX, RDM, ArtNet, sACN, and RDMnet...the future of DIY Christmas.
    Designer of the PropController an open source single-board hardware platform designed for lighting and prop control.

  6. #16
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    No, I am putting the dimmer though the toughest testing I can and seeings what kind of event timing it will handle. The toughest test I could come up on that was to setup vixen with a given event timing and and blink a channel at that. at 100ms perfect, at 50ms, best I can tell perfect, get much lower, missed events. of course it syncs back because vixen is still kicking out the right info at the write time. From what I can tell the full dmx string out of the dongle is taking just a little longer than that to complete so over say 10 cycles of the lite it reaches a point where the dmx string is behind and starts the last command just before vixen gives it the next levels. This makes it miss that packet. by the time dmx sends the next string with the update we are ready for the next state of the light and you have a partial event that looks as if we missed an event. Then all is good for maybe 9 more dmx passes. I know this is a muddy explaination but I hope you understand. the DMX refresh is just a little to slow for this kind of event timmings. I also see sometimes the dmx stream is not like clock work. I believe this is the nature of the beast with the open as it has no brains and if the computer gets an interrupt or is busy at the wrong time this could lead to this. I keep all but the needed processes going on the machine to help and I dont know that its noticable in the lights as a whole. But maybe this is part of the problem on the low event timings also. Most people will not need 25ms but everytime a controller has been design on here before it was asked for by some. KC I think the old joke was they wanted to Twinkle the lights. and the answer was (what ever that is). Funny thing is other than the money difference the Pro unit woud be better, and the plugin would be bone simple to write for looks like you simple use the virtial com and stream the values to it. But on a side note I have an idea that I am posting in the DMX section cause it belongs there as its hardware. Will both of you read and give me feedback on it? Thanks
    [url]www.diylightanimation.com[/url]

  7. #17
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    Well it sounds to me like a two part issue, its sounds like the level changes aren't making into/out of the plug-in fast enough and this may be due to DMX's refresh rate; some level changes are being skipped/dropped.

    Values being skipped/dropped isn't really a surprise. During a fast fade several values may be skipped/dropped, even with skipped values when dimming or controlling moving lights visually you wouldn't notice. There is a small chance you may notice with LEDs, and you would defiantly see it on a DMX tester. In the end DMX isn't really designed to transmit every single level change, the limitation as you suggested is the refresh rate of the packet and the inter-byte spacing. Top of the line consoles have a direct "pipe" to the DMX interface and start a new packet immediately after the previous one. They also don't have any inter-byte spacing. If memory serves KC had to add inter-byte spacing to ensure data integrity to the Open DMX dongle, hence the slower refresh rate.
    DMX, RDM, ArtNet, sACN, and RDMnet...the future of DIY Christmas.
    Designer of the PropController an open source single-board hardware platform designed for lighting and prop control.

  8. #18
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    That would explian why the refresh rate is not as fast as I would expect. I do not notice anything in the fade its flashing the lights where I see it.
    [url]www.diylightanimation.com[/url]

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