After much trouble with power supply I managed an ATX power supply and hooked it up to power my uno from the a type B USB (Lets call this the Supply connector).
Any time I have to upload a code I have to remove the USB cable put another usb cable from my computer and then do it.
Can I use two remaining data wires of the supply connector and connect them to the computer.So I power the UNO from the external ATX but the data pins from the UNO USB are always hooked to the computer.
I will maintain a common Gnd
AFAIK it should be possible to supply power to the Arduino on its Gnd and Vcc pins. No need to cut off the USB power line then.
SO I tried it... Sliced open a TYPE B usb cable ... took out the red and the balck wires hooked them onto my external ATX and wallah it works.... BUT!!
The arduino cannot be detected by a laptop (Win 7 USB 3) how ever it can be detected and operates normally to a desktop... USB 2 XP.
The Uno is being supplied by an external ATX PSU and the data connections are still intact to the USB male.