Connecting computer to pixhawk through TEL port

Hi guys,
I’m trying to connect my pixhawk cube to the computer through TEL1/2 (instead of by regular micro USB port) and it doesn’t seem to work (I’m using FTDI cable, of course).
I know there is a designated “usb” port on board, which I need for other purposes. Any ideas?

Thanks in advance,
Matan.