We resell something similar, from DFRobot: http://www.robotmesh.com/usb-power-detector http://www.robotmesh.com/usb-power-detector One of the ports has the dat

We resell something similar, from DFRobot: http://www.robotmesh.com/usb-power-detector http://www.robotmesh.com/usb-power-detector One of the ports has the data lines connected, the other port doesn't, so it could be used as a USB condom.