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

Martin Flynn maflynn at theflynn.org
Fri Nov 30 18:14:27 EST 2018

On 11/30/2018 4:46 PM, Ethan O'Toole wrote:
>> 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 good.
>> 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:
> https://docs.google.com/presentation/d/1MqJrwKCAL_tw4t-VnQWevSvXTlszwFy-clECES2YwY8/edit?usp=sharing 

Lighting packs are Strand CD-80 with the aftermarket Johnson Systems  
DPC-24 control modules, so yes, it's definitely DMX-512

Looking at the Open DMX USB as an option

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