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John John

Set DMX refresh rate

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Hello,

Is it possible to change the DMX refreshrate in the  FLX S24 desk?
Because the band I'm controlling the lights for has some chinese fixtures :-(  who are funking and glittering all over the place with normal DMX.

In the old system they where using they set the refresh rate up so the moving lights were working properly.



 

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Hi John,

No, it's not possible to change the DMX refresh rate.

Have you tried disabling "RigSync"? If the fixtures have poorly implemented DMX this might be causing problems.

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Hello Jon,

Disabling "rigsync" makes no difference, I think the fixtures have a elcheapo DMX board.
They worked around it by changing the refresh rate on a Enttec DMX usb pro dongle.

 

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Try setting your problem fixtures to a high DMX address, so they are forced to read the whole DMX packet.

However what's interesting about this is that the FLX* will be sending out a full 512 channel DMX packet so the refresh rate is naturally as low as it can be (without adding padding to the break). Maybe the entec sent short packets (maybe up the the top address used?) and thus the "refresh rate" was changed to emulate full 512 channel packets.

If the fixtures can't take a fully formed 512 channel DMX packet then they must be *really* rough! Even "off the web" Arduino DMX receiver code isn't that bad!

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32 minutes ago, kgallen said:

Try setting your problem fixtures to a high DMX address, so they are forced to read the whole DMX packet.

I'm going to try this one out tonight, I'll keep u posted.

Thanks, John

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Unfortunately this also makes no difference, so I sent an e-mail to the chinese supplier and awaits his comment.

Thanks, John

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Have you got a DMX terminator on the end of the line? If you have multiple chains have you used an active DMX splitter?

Even with a 'poor' fixture this problem seems strange. 

Can you try the fixtures one at a time with a short cable from the desk and note the results?

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Hi,

I've tried all of that, one at a time, terminator at the end, without terminator, XLR5 output, XLR3 output, with booster, without booster, short cable, long cable.
It all makes no difference :(.

It's just a bad product, but I'll keep on trying.
I'm at the bands warehouse Thursday or Friday so I will read-out the Enttec dongle and post the DMX settings they were using on these spots.

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The Enttec setting are:

Packet output rate: 17 p/s

MAB (mark after break): 1 (10 micro sec)

Break Time: 1 (micro sec)

 

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Those settings don’t seem compliant to the table here https://en.m.wikipedia.org/wiki/DMX512 (MAB transmit min 12us and break transmit min 92us) and don’t stack up to 17 frames per second at 250kb/s. 44 frames per sec with MAB of 12us and break of 92us stacks up as a 22.676ms frame. So the Entec must be sending much longer break or MAB to reduce the max 44fps to 17fps. Even if the break were 1ms that still gives 23fps.

How bad can those fixtures really be. It seems hard to envisage they could be that bad!

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