Channel Formatting for DMX


I’m having trouble formatting channel information for my DMXout Chop.

I using a Eurolite USB-DMX512 Pro and have confirmed it works with PC-DImmer software.
The light I’m trying to run is a Stairville Par 56. It takes 7 channels.

Attached is a simple example of how I’m formatting channel data for DMX.

What am I doing wrong? How would I expand this to more fixtures?
Any help is appreciated!

DMX.toe (4.28 KB)

Also, I’ve confirmed that that my interface is on Com Port 3.

What channels are supposed to do what going to the fixture?

The thing with DMX is you should always send full channel list, even if you aren’t using the other channels on the fixture. So if this has 7 channels, you should make a Constant CHOP with blank channels, and merge them into the proper order. So for instance, if on your fixture the DMX channels are:


And you only wanted to control XYZ, you’d need to create a blank Constant CHOP, use a Merge Chop to fill channels RGB, then you could append you xyz channels to the Merge CHOP.

Basically the channels go by index, not by name. So if you want to control channel 5, you need 4 blank channels before it. And similarly if you want to add another fixture, you’d need to fill up the rest of the fixtures channels, then you’d be at channel 1 of the next fixture, as which point you’d fill up channels you don’t need, and etc etc.

That make sense?

I often use a replace CHOP for this. Create a constant CHOP with 512 channels (chan[1-512]) and use it as the first input to a replace CHOP, now use the channels you need for your DMX fixture as the second input using appropriate names. So if your fixture starts at DMX channel 7, your input channels should be named chan7 - chan(n). This way they always end up in the correct position.


Thanks for the quick replys.

So I read through both your suggestions and adjusted my network. However I’m still not getting a response.
The fixture has 12 dip switches on the back. When 10-12 are turned off the fixture is in DMX mode. Dip switch 1 is currently set to on for my fixture’s channel address.

Attached is the new .tox and also a picture from the fixture manual describing channel assignments.
DMX.toe (4.29 KB)

So from the Doc I would assume following DIP switch settings:
Dip 1: on
Dip 2-12: off

otherwise your network is fine, except for the the channel names in the second input: For the replace CHOP to work, the second input Channel names need to match channel names from the first input, therefor R0, G0 and B0 should be named R1, G1 and B1

Can you somehow see if your USB DMX device is receiving data from TouchDesigner?
Does the DMX Out CHOP connect sucessfully to the Device (you would see a little yellow warning triangle on it otherwise)
Does the Speed channel need to be something larger then 0?

For connecting more lights of the same kind I came up with the structure as in attached file.
First I created a constant CHOP with all the necessary channels to control this fixture and set the constant CHOPs channel length to 73 samples (512 available DMX channels / 7 channels per fixture ).
Next I use the shuffle CHOP to split up the multisample CHOP into single channels in order to then replace them with the Channels per device.
Now comes a whole shuffle chain which first rebuilds the channels to a multisample channels, next Sequences all the channels by sample order (this way your output channel is in the order R,G,B,M,S,MOD,D) then scale it the 255 value range and finally split it again into single sample channels ready to be send to the DMX Out CHOP.

Hopefully you succeed in connecting to the fixture!

DMX.vM.toe (7.54 KB)

Hey Markus,

Thank so much for the help. I actually got the system up and running yesterday morning. Was so simple once I understood how the interface wanted to see all the channels.

Right now I am creating a ConstantCHOP for each fixture in my rig with 7 channels per fixture. Giving them each the proper naming conventions for their fixture. These all get fed into a MergeCHOP that then goes into a ReplaceCHOP along side a Constant filled with 512 channels. The channels all get scaled to 255 and then fed into the DMXout.

It working great so far. I’m running this all in Touch and using Ableton Sync to trigger synced projections and lighting. Will definitely post a video when the production gets documented.

Thanks again for all your help.
Attached is the current working network.

Javier Cruz
DMX.3.toe (7.34 KB)

Hello Everyone!
I’m refreshing this topic becouse I’m using a Eurolite device and the same network you linked in the topic but it doesn’t work.

Touchdesigner 099 - Windows 10
Eurolite USB-DMX512 PRO Inter­face MK2

The device works fine, tested with Freestyler DMX, and is connected to COM3

The Chop DMXOut recognize it (in the “device” list I can choose between “*” and “AI04HDM7”)
In the Chop DMXOut Input there is a 512 channels signal, values form 0 to 255 (I used a Constant Chop + Replace Chop + Math Chop Network)
In the “Interface” Option of DMXOut chop I have these options:
“Enttec General Serial”, “Enttec USB Pro”, “Enttec USB Pro Mk2”, “Art-Net”, “sACS”.
No option seems to work.

The DMXOut chop have no Warning (Warning appear if I choose any other COM port except to COM3)

Just, the red led on the Device tell me that the device is not reciving signal (or not reciving a correct signal) from the pc.

Please, somebody can help me? Thanks so much! :slight_smile:

This is a great idea as often you turn up somewhere and the lights you need are addressed way down the DMX list, but how does one get 512 channels with a Constant CHOP - do you need a bunch (13 if max 40 channels per Constant) of them merged>? I’m assuming there’s a smarter way to do this?

A very noob Q I know

If you literally put “chan[1-512]” into the name of the first constant name, it will actually spit out 512 channels. With the brackets, but not the quotes, just everything inside the quotes

I just bought an Eurolite USB-DMX512 Pro am try to get it run with TD. I tried all your sugegstions but dont get control over my “Stairville Led Bar 240/8 RGB DMX”. What I did up till now:

  • I also tried with th ePCDimmer Software and here I can control the light
  • My dmxoutCHOP doesnt show me the yellow triangle. I am connected via generic and COM4 Port.
  • I created a constantChop with 512 channels and scaled my values to be between 0 and 255.
  • I tried all of your exemple files.

@ Javier: Do you get the small led on the Eurolite device to be green or does it stay red? Did you get your device to run stable?

Dies anybody have an idea? I also attached my testfile.
I would apreciate any help!
dmx test.toe (6.9 KB)