problem with USB hub

[Antoine Jacoutot]

Hi :)

I use a USB hub with a scanner and a printer plugged-in under FreeBSD-5.2-RC2.
The USB hub is self-powered. After some time of inactivity, the hub turns of 
the ports where my devices are connected which means I cannot access my 
printer nor scanner anymore...
I there a way to tell FreeBSD to send some activity to the USB port where the 
hub is connected to it does not turn off its ports ?
I would really appreciate since the only solution for my printer and scanner 
to work again is to unplug and replug the USB hub.

Thanks in advance.
Regards,

Antoine