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USB User Interface Error Detection
The USB error detection and correction scheme uses WMI event-driven architecture to resolve errors. The interface notifies the user when a problem occurs on the bus, gives information about the error, and suggests solutions.When the user clicks on an error message, a dialog box appears that shows the following: A description of the error condition.
The tree-view, which is a topological view of the bus. The tree is expanded so that the device in question is displayed, selected, and in bold.
A recommended user action, which depends on the current topology of devices on the bus.
The following six error conditions reported for USB devices result in messages that give error descriptions, and some also give troubleshooting advice: Electrical surge on hub port. Either a device attached to the port, or the port itself, has drawn more current than allowed, and the hub turned off the port. The port will not function correctly until you reset it. If the device is the cause, it must be detached before resetting the port. To reset the port, disconnect the device, and then click Reset in the dialog box. If the port is the cause, close the dialog box, and do the following to re-enable the port:
Disconnect the hub.
Re-attach the hub.
If it is the root hub, unplug all attached USB devices from the computer, and (if they have power supplies) unplug them from the electric supply. After a few moments, reconnect the devices. The computer can be restarted at any time.
USB hub port power exceeded. A device that requires more than 100 mA has been plugged into a bus-powered hub that can supply only 100 mA to each of its ports. The device will not work until it is plugged into a self-powered hub, or into a root hub, that supplies 500 mA to each port. Disconnect the problem device and reconnect it to an unused port that meets its power requirements. (The error dialog box lists the appropriate port in bold.)
USB host controller bandwidth exceeded. A device request for allocation of bandwidth has failed because the USB host controller is in full use and has no spare bandwidth. Typically, devices support several settings at various levels of bandwidth. A device tries to allocate the highest bandwidth, progressively metering itself back after each bandwidth allocation fails. Repeated requests trigger an error condition.
It is recommended that you close some applications that are using USB devices that use bandwidth. In Device Manager you can view the property page for the host controller to see bandwidth status. Pressing Refresh in the dialog box after making any changes updates bandwidth data to show whether bandwidth is freed. Maximum number of hubs surpassed. Six or more USB hubs are linked in a chain, and the USB specification allows a maximum of five. It is recommended that you remove the most recently connected hub and connect it to a port that is highlighted on the tree view list in green (signifying that it is free and recommended).
Device enumeration failure. A device is plugged into a USB port, but the operating system does not recognize the device. The failure can have various causes. For example, the device might not initialize properly when it is plugged in, or the device driver might be faulty. If the cause is not a permanent malfunction in the physical device, unplugging and plugging the device in again might allow it to enumerate properly.
Identical serial numbers. The serial number in a device, if it exists, must be unique for each device that shares the same USB Vendor ID and Product ID. Occasionally hardware vendors mistakenly program devices with identical serial numbers. When two or more USB devices with identical serial numbers are plugged into the same system, only the first one plugged in functions. For further assistance, contact the hardware vendor.
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