# USB Hub - Unknown Device



## Sepherz (Feb 5, 2008)

I have a usb 2.0 POWERED hub, connected via a 5 metre extension cable. It shows up on my computer as Unknown Device. Im running Windows XP Pro SP3 with all the lastest updates. The hub connects fine if I take out the extension cable. And the extension cable works because everything but a hub connects to it. Currently my wireless receiver (for mouse and keyboard) is connected to it.

It used to work on another computer (emachines 610), which was also running XP Pro SP3. But on this computer (Dell Dimension 4500), it doesnt want to install the right driver for it.

I cant force install the "generic usb hub" driver. If I go into update driver, and select the drive from a list, if only shows a driver called "Unknown Device Driver".

Any ideas?

Cheers!


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## justpassingby (Mar 11, 2007)

Since the hub works well when you don't use the extension cable it's not a driver problem. Sounds like a signal problem to me.

Note that USB hubs don't do well on extension cables so I don't know if you'll be able to solve that problem.


> A USB device that can be configured by host system software when it is plugged into a port on a specification-compliant hub may not be configured successfully when it is plugged into the end of the USB extender cable
> 
> Extender cables have been shown to be electrically unreliable when participating in data transfers over the USB bus


Source : USB Hub Design and Windows

Make sure you have an USB 2.0 extension cable. You can test the speed of your cable by connecting an external USB drive on it and see what transfer speeds you can achieve. Copy a big file (500MB or more) to the drive. USB 2.0 should allow for constant 20MB/s, capping at 30MB/s. If it's less than 3MB/s then the cable limits the speed.

5m is the max length at which you can hook an USB device without needing to repeat the signal. Most Hubs have a small cable between the hub and the usb plug which means the total is longer than 5m and there can be loss in the signal.

Usually each usb controller can only power up to 500mA. Check how many milliamperes are drown from the usb port the extension cable is plugged into : go to start => run and type devmgmt.msc. Expand universal serial bus controllers, double-click each usb root hub and go to the power tab until you find the one with your hub. Try different usb ports to give the extension cable and hub their own usb root hub.


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