Here's some Optical Printer wiring diagrams I've drawn over the years.
Simple 3 Axis System
The most common systems I do are 3 axis systems: Camera, Projector, Fader.
With home sensors on each axis so the computer can home each axis on startup, buckle/viewer sensors, and optional forward/reverse tension control, and optional separate computer control for deenergizing the axes (in place of mechanical deenergize switches):
5 Axis System
Another common system is a 5 axis system which includes Aerial projector, Main projector, Capping shutter, Camera, and Filter wheel for high speed YCM or other special color printing:
16 Axis System
The largest system OPCS supports is 16 axes. These printers really aren't done much anymore; they were for doing special effects, but recently someone came to me asking for a quote to do a 16 axis system. (Most "modern" printers are doing simple printing for restoration or format conversion, maybe sometimes fades/dissolves or re-framing, or liquid gate film cleaning)