[vcf-midatlantic] Kind of OT: RS-485 to DMX-512

Ethan O'Toole telmnstr at 757.org
Fri Nov 30 16:46:52 EST 2018

> Trying to get a lighting controller to talk to 1986 vintage microprocessor 
> based lighting control packs.

This is my world!

> The PHY layer of DMX-512 (lighting control protocol) is RS-485.

Yes. Given that it's 1986, are you 100% sure it's DMX-512? If so you are 

> Anyone have code samples that could be used as a starting point, or should I 
> break down & buy the  USB to DMX-512 cable?

You can get a cheap ($7) FTDI based USB to RS485 dongle from amazon or 
eBay. The FTDI chip can't natively do the proper break space but they have 
a trick of resetting the chip to get the proper spacing for the restart of 
next set of 512 channels transmitted.

With this adapter (which is similar to the $50 EnTec OpenDMX) you can use 
free software in windows like FreeStylerDMX or QLC+, or if you wish to go 
the linux route there is the Linux OLA package which can do Artnet and 
1.31 sACN in and translate over to physical DMX512 (via RS485 dongle.) OLA 
has a web interface that lets you tickle the channels with a web fader 
board, and could easily be scripted.

At the laser enthusiasts gathering I go to I've done a presentation or two 
on running OLA on a PI to do cheap Artnet/1.31 in over to DMX512. I can 
dig up the slides.

Actually, since the presentation is on the evil cloud I just opened up 
access and here is the steps to install the OLA bits on debian/pi:

 		- Ethan O'Toole

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