Raspberry Pi connection

Hi, I got one small project and maybe someone already have program in Python and can help me. This is home research project and do not have any commercial value but of course Im ready to pay for help. Namely I want to mu home robot (small arm) connect with my Raspberry Pi. So every time when robot came in "servo" mode, robot send a signal. Wire will be connected on my Raspberry Pi imputs/outputs. So I want program in Python, who's can recognise that signal and record time and send it in excel application. And on the end of day I want to know every day how long robot was in "servo" mode. I know this is very small and simple project but I really need it for my home research.