On a Windows Vista-based computer that uses Universal Host Controller Interface (UHCI) USB controllers, a USB device takes a long time to resume from “selective suspend” mode. Usually, the USB device takes 500 to 1,200 milliseconds (ms) to resume from this mode.

Therefore, USB devices that are attached to the UHCI USB controller may take a long time to respond. For example, assume that you are using a fingerprint reader to capture user fingerprints. The fingerprint reader is attached to the UHCI USB controller on a Windows Vista-based computer. If the fingerprint reader is in “selective suspend” mode, the system may not capture the fingerprint after you swipe a finger on the receiver of the fingerprint reader. This behavior occurs because the fingerprint reader takes a long time to resume from “selective suspend” mode. You must swipe your finger again for the fingerprint reader to capture the fingerprint.

Note: Typically, it takes about 20 ms to resume from “selective suspend” mode when you use either of the following configurations:

• Microsoft Windows XP-based computers that use UHCI USB controllers
• Windows Vista-based computers that use Open Host Controller Interface (OCHI) USB controllers