Due to panel constraints for my 740, I am using a 90 degree angle usb to serial cable(points directly back through panel) and have cut the cable in order to install a db-9 connector that will work with the Dynon D10A. Pin 3 is used for the transmission(data) line and pin 5 is for ground but which of the four wires found in the cable is the transmission wire used for pin 3? I assume the black wire is for ground. When looking into the usb case with the white "floor" on the bottom, the four contact strips from left to right match up with black, green, white, and red wires. Thanks, John