ArtNet to DMX node?


4 posts
by Elusid » Tue Nov 06, 2012 6:20 pm
I work at a dance club / event center as a light tech and I'm finally getting the opportunity to mess around with my new Pi. One thing I would love to figure out is how to use the RaspberryPi as a node to convert ArtNet to DMX512/1990.

I found a tutorial on installing OLA on the Pi which does exactly what I want except it uses a USB to DMX converter as well. I want to find a way to output a DMX signal with as few extra components as possible using either the onboard GPIO or UART. DMX512 is based off of the RS-485 standard and from what I’ve read, UART can use it as well.

I came across THIS UART to DMX bridge document with a schematic at the end but I’m not sure how to get it working with the Pi. If anyone can help me create an ArtNet to DMX node with the RaspberryPi that would be absolutely incredible considering the cheapest all-in-one ArtNet to DMX node is $200. I know the lighting community would love it!


Here's my brief explanation of now an ArtNet and DMX system work together
Code: Select all
 DMX512 has been the standard in lighting control since 1990 and is used for things like dimmers, intelligent lights or effects throughout the entertainment industry. Each device on the DMX network must be addressed between 1 and 512. Each channel can control one attribute. For example, a 48 channel dimmer rack would consist of 48 separate 20A dimmer cards (generally) using a single DMX512 channel each. A strobe light often uses 2 channels for controlling the intensity and rate. A single moving head generally uses 11-32 channels which adjust things like the dimmer, pan, tile, cyan, magenta, yellow, shutters, zoom, focus, iris, gobo1, gobo2, gobo rotate, 5 facet prism, prism rotate, and whatever else the manufacturer designed it to do.

For most venues this is plenty but when you start talking about concerts and dance clubs, which heavily rely on intelligent lights and LED screens, 512 channels just isn’t enough. That is when you start running multiple DMX512 networks also known as a DMX universe. Most light boards output anywhere from 1-4 DMX512 universes natively but each cable needs to be run independently and if you are using any kind of LED video wall or large RGB LED system you’ll need several more universes. This is where ArtNet comes in

ArtNet allows you to send multiple DMX512 signals over IP. Connected to the network are IP to DMX nodes. Each node can be assigned to output/input any of the universes over the network. This SIGNIFFICANTLY reduces wires since all that’s run is a single CAT5e cable instead of a DMX run for each universe. It also allows you to control anything from anywhere, which is exactly why I want it.
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Joined: Mon Jul 16, 2012 10:32 pm
by Arjan » Mon Nov 26, 2012 5:52 pm
Hi,
I've found this one http://www.mathertel.de/Arduino/DMXShield.aspx
a DMX shield for Arduino. We probably could easily adapt this for the RPi UART.
Posts: 130
Joined: Sat Sep 08, 2012 1:59 pm
by psytron » Thu Jan 03, 2013 9:34 am
If you require bidirectional data flow I.e. rdm or you wish to use it as a slave and master you will need a little programming for deciding when to send / listen . If you just wish to send data use the simplified designs from that page. You will need to tell ola to use the UART on the RPI instead of the USB as well as setting it up to send at the correct baud rate. I am lookingat using a RPI to take art net from ola and sent out spi to led pixels. So a very similar approach could be used. There is a project called light pi which I believe is already doing this. Have a quick search and you should find some more info about directing ola to something other than USB. Hope this helps...
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by Elusid » Fri Jan 04, 2013 2:24 am
Thank you! I'll take a look at it. RDM would be nice but just sending would be alright too.
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Joined: Mon Jul 16, 2012 10:32 pm