FOLLOW THIS TUTORIAL AT YOUR OWN RISK!!!!!
My astro mount is beside my garage with a PC just inside to control it. I can control the mount and cameras remotely from my home study using Google Remote Desktop – but not my Orion AccuFocus focusers.
I read a forum post (that I can’t now find) which explained how to control the focuser over USB. I adapted it slightly to avoid the need for stripping one end of the focuser cable by adding an RJ10 socket.
Component links: USB Relay – RJ10 Socket
The wiring diagram I used is here. Note that the wires to the socket are soldered to the left and right pair of pins respectively.
To control it, I modded an app I found on the net to give me a selection of timed pulses in both directions. This gives fantastic control for fine focussing.
The whole thing cost less than £10 but means I can now control everything from the comfort of home – or even further afield.