R and G channels reversed with DMX lights

Hi all,

I am having an issue where the red and green channels are swapped when I output textures to DMX light strips. I have tried this with both RGB and RGBW LED strips and an LED ring. I am pretty sure all the LEDs I’m using are ws2812.

In some cases, I can simply swap the R and G channels in LightAct before a Color to Texture or a Gradient node, but this fails if I want to use any of the texture generating nodes (Color Palette, for instance).

These are some of the LED fixtures I’m using to test:



And this is my DMX controller:

Thanks!
Scott

Hi Scott,

That’s weird. This has been extensively tested and from the Data section in the properties of an Art-net node in the Devices window, it also appears that the ordering of the channels is correct.

The data shown in the Data section is as close to the actual output from the server as we can get, but if you want you can also connect a DMX Tested to check what’s actually in the cable itself. We use DMX Tester from Swisson, but you can get others I am sure.

Good luck,
Mitja

Hi Mitja,

Thanks for letting me know. I see the same information as you show above – the R channel affects the first channel of DMX data that is streamed, G is the second channel, B is the third, and W the 4th. Unfortunately, the color that actually appears on the LEDs is different than the color being output, and it only matches the intended color when I swap the R and G values. In the attached image, I’m outputting 255 for the R channel, which looks correct, only the LED strip lights up green.

It seems like this is an issue on the hardware side. We are in touch with some collaborators who have seen the same issue using different software with our particular LED strips and controllers, and they think the channel order on the LED chips might actually be GRBW rather than RGBW. I will let you know if I learn anything more about this, we’re doing some more testing later this week.

Perhaps this is a feature request for the next version – it would be helpful to be able to globally swap the channels for the whole system, in case of strange things on the hardware side. Maybe there could be a “GRBW” option in the Pixel Type for eDMX fixtures? Or maybe there’s an option added to the “Overrides” section of the Art-Net node options in the Devices window that allows you to switch the channel order.

Thanks as always for being so responsive!

Scott

Hi,

That actually came up yesterday during a dev discussion about Art-Net. @David, let’s make sure we add these additional pixel types as an option in the Fixture Editor.

Thanks,
Mitja

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@smsmith_CM Apart from “standard” formats you will also be able to pick “Custom” where you set number of channels per pixel and assign value to them. This will enable you to create your own format (any combination).

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@David @meetya That sounds great! Seems like a great solution.

Any guess on when that might be released? We’re in the last couple of months of fabrication / installation, so I think for now I will just swap the R and G values of the colors in LightAct before output. But, looking forward to “custom” pixel types!

I think a ‘couple of months’ is a suitably open-ended deadline for us to be willing to ‘commit’ to it. :wink:

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