The USB TAP probe is powered through the USB cable and does not use an external power supply. It is designed to be plugged directly into a host computer, but also can work with self-powered hubs. Bus-powered hubs may be unable to provide sufficient power for the USB TAP probe, which requires 200 mA. If insufficient power is available, your host operating system will indicate this failure and the probe will go into a low power suspend mode. If your hub is not able to provide sufficient power, connect the USB TAP probe directly to your host PC, or purchase a self-powered USB hub.