Update, got it working. I followed the first wiring diagram loosely to run the probing circuit directly to the probing input pin on the 7i96s. Instead of a fancy relay, I used an automotive relay and I didn't have any 1N4007 diodes, so I used a couple 1N4002's from one of my old Megasquirts. I used a used Chinese 12v power supply from my old 3d printer. Seems to work fine for now, if it fails I'll upgrade components to match the diagram more closely. Thank you all for the help and advice, I wouldn't have been able to figure this out without you.
