I have a few quadcopters and normally when I power them on the ESC's beep once. After installing the Pixhawk 2.1 I noticed that when I plug the batteries in the ESC's beep one and then beep a second time a few seconds later. Why might this be happening? If I disconnect the ESC wires from the Pixhawk the ESC's only beep once, so it seems like after the pixhawk 21 is booted up it's telling the ESC's to power cycle. Anybody else have this experience or advice on why this might be? Thanks in advance.