The "Advanced Button" is the goto button for this project.
About "tapping the 12VDC" to a versiport. May I suggest using optocouplers (or optoisolators depending in what part of the world you're in) to couple (or isolate) the generac from the versiports.
The Crestron versiports have a common ground and the 7 LEDs of the generac might not, and even if they have I would not trust connecting them directly. Building a board with 7 optocouplers is not so complicated and can save you a lot of misery.
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Oh man, you don't even have to build it!
https://www.amazon.ca/Channel-Optocoupler-Isolation-Converter-Isolator/dp/B09S3XTM5P/ref=asc_df_B09S3XTM5P/?tag=googleshopc0c-20&linkCode=df0&hvadid=683150834842&hvpos=&hvnetw=g&hvrand=2513852794165375712&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9000411&hvtargid=pla-1869623874401&psc=1&mcid=b4aea703722032ed9634788023f5a0cf&gad_source=1
