I'm trying to understand the purpose of the B/D connection in the instruction manual for the M LINK Multiplex receivers. I don't understand what's explained here, nor do I fully understand what it's for by reading the forum. I seem to understand that it's a connector for connecting the receiver to a PC, but I'm not sure what it's for. It also says something about connecting multiple receivers together and something about batteries. I honestly don't understand anything. Can someone clearly explain what this B/D connector is used for?