The FLSCU's command the control relays to power the valves either open or closed.
Although captmilo above chose to write in text speak I believe he is correct in what he's saying.
Great debate though, I can confirm that on the ground tripping and resetting all the transfer valve c/b's does cause them to open. Opening the refuel panel causes them to close again.
I've had c/b's snap due to the plastic going brittle on older Airbus so i'd advise against tripping any in flight unless your procedures or maintrol specifically ask you to.