Thank you very much the replies.
Although plugging and unplugging works, the PC and the attached USB
devices are at a remote place. Moreover, we have hundereds of USB devices
that are part of a
testbed so it would be ideal if it is possible to handle things
automatically.
However, I will post the kernel messages soon.
Manjunath D
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On Tue, 29 Jun 2010, Alan Stern wrote:
On Tue, 29 Jun 2010, Manjunath Doddavenkatappa wrote:
Dear all,
We have a sensor device with a USB connector (device's name is
TelosB in case if your aware of it). We use USB active cables to connect
such devices to a Linux PC (2.6.22-14-generic). Length of these active
cables range from 5 to 25 meters. Problem is while long 25 meter active
cables are used for connection. Communication with a device connected via
such a long cable is fine most of the time, but connection would go down
at least once/twice a day (although the corresponding /dev/ttyUSBX is
visible). Each time the connection is lost, removal and insertion of the
USB kernel module "ehci-hcd" will make the connection alright again
(modprobe -vr ehci-hcd; modprobe -v ehci-hcd).
Is there any way to fix this without having to remove and insert the
module every time. I am new to USB framework on Linux.
Like Felipe says, this is almost certainly a hardware problem caused by
your active cables interacting poorly with the host controller.
However... If you are still interested in a way to solve the problem
without unloading and reloading ehci-hcd, there is a simple answer:
Unplug and replug the cable.
Alan Stern
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