okay, thanks again!
I see in that link of yours (Why do serial commands from Python don't run Arduino when sent in a for loop?) :
you suggested a method of using pyserial module. I'm not familiar with it, but will try to understand how it works.
for the second part (i.e for Arduino to provide a high signal to trigger the acquisition)- can you please explain a bit more? because that part is not suggested in that link if I understood correctly(?)