https://m.youtube.com/watch?v=V1IMmLDa1Po

This maybe how it works and should help you program it

I know this is an ancient thread, but I am working on a similar machine, just with a 6 tool umbrella.  Did you get this working?  If so, can you post the code? 
I'm modifying the code that CNC4PC has on their site and have the basics down, I think, but I need to get the umbrella rotation and counting worked out.  Also, it'll need to be homed in the machine homing script, but I don't think that'll be too bad.

Thanks!

Mike

I used to do the programming for one of those back when they were new! It was challenging to load large tools because the distance from the tool load button to the spindle was just about the length of both arms stretched out straight. I hope you manage to resolve that issue.

you need put the event that raise from counter in the screnn load script
this will count very time and as i remember this old system you must delay alitele bit after the sensor litght ,this delay its shuld be as parameter acording yours mechanizim
then onther register parametr that will tell if you rotate cc or ccw
then its finish that write the script
but you must keep the last value in the registry ,or if you have onr sensor for homing its also script you must do when finish yors axis homing
---its much more complex then normal rotary magazine as axiss,so if you can change to servo /steper motor you will save much head hace