Battery/Master Switch

Hi,I have just started building my home cockpit, using opencockpits I/O cards. I am wondering how I wire up the battery/master switch. I want the sim to recognize it's position so I can wire it to the input card like any switch, but I also want it to work IRL in my cockpit (ie all power on/off to panel). I don't think I can physically put the power supply through the switch as it will send it to the card. It seems I can do one or the other - I can either have it talk to the software, or it can physically cut power to my panel. I don't see how one switch can do both as it will short out if power gets in contact with switch gnd. Has anyone done this? Can you share wiring diagram for bat/master?Thanks,JP