I was wondering if there was anyone with experience in controlling a few hundred solenoids via the Duet WIFI? I have looked online on methods people use basic arduinos but it seems like a lot of the information is outdated. Any guidance into what expansions boards I can use would be super helpful!
I would prefer to use the Duet architecture because it is so handy and I can post my findings here for future reference! 
@dc42 I am using a color spectrum analysis from the openCV library.
Okay I think I understand. I remember those DRV8860 drivers from the old RAMPS boards a few years back. I could daisy chain all the DRV8860's together on my own little breakout board, attach the signal pins to the outputs of the DRV8860's, then I connect the inputs to these SPIO pins:
How do I send my serial signal from my computer/web interface/gcode file to those pins to control the DRV8860's?
@snoozer It is 2019, PLC is expensive, inflexible, heavy, clunky, and it is just outdated tech. I also want to control the whole system through the duet and off the shelf IC's. The duet and arduino in general is awesome to work with.