I too have the same problem. I tried to setup on a XP computer but could not get the serial port active I tried quite a few drivers just would not work Installed windows seven on it and the serial port now shows as 3 and 4 . Four works 3 does not. Also when I do a start I get the error No reply received from the drop controller. I tried it on 2 other computers running windows 8.1 and one running 10 same error.
Does the computer really need to hear back from the arduino after it does a cycle? Can you not just send a signal to the arduino the repeat it again and again? Just wondering.
When I don’t use the dropper as a drop controller I use the signals to drive a Gear motor on my macro slider to do focus stacking then trigger the camera Just another way to utilize the Drop Controller