Maurizio said:
Hello:
I have 6 USB ports on my laptop, recently I tried to connect a
USB-to-Serial to it, it's accepted on some ports, and not recognized on
others.
is there a tip to be accepted on all?
thanks in advance.
On the Windows side, using usbview or uvcview, would allow listing
the plugged in USB devices. But it's not clear to me, whether this
is sufficient to distinguish between a hardware problem, and a registry
content problem.
The thing is, the OS is a bit dependent on the pre-existing information
it has in the registry. For example, the first time you plug in the
USB to serial, it might be assigned a COM port like COM3. At least
my USB to serial, has an electronic serial number. That is so the
OS will record the serial number, the fact COM3 is assigned, then
the next time the device is plugged in (into a different USB port
perhaps), it will still end up with COM3 assigned to it.
Getting a copy of USBView or UVCView isn't that easy, so another
alternative, for testing hardware, is the usage of a Linux LiveCD
and the "lsusb" utility. That would not be dependent on the Windows
registry, and would be more likely to just report low level hardware
activity. It will show a VID and PID number for each plugged in USB
device, and show the USB port number. Ubuntu is an example of a
Linux LiveCD, but there are other better alternatives.
http://reformedmusings.files.wordpress.com/2008/12/scan-lsusb.jpg
There is a "cleaning procedure" of sorts, for fixing USB stack issues.
http://www.usbman.com/Guides/Cleanup Device Manager Safe Mode.htm
That can also be done with a copy of Microsoft "devcon.exe". The
devcon utility, is like using Device Manager, only from the command
line, and allows scripting. The script in this example, relies on
invocations of devcon.exe to clean up the USB stack (remove
potentially corrupted entries, like way too many entries for
the same device).
http://www.robvanderwoude.com/devcon.php
http://www.robvanderwoude.com/files/renewusb_2k.txt
(Change extension to .bat)
That relies on calls to the devcon utility, to remove traces of USB
from the registry, and start USB enumeration all over again. That particular
script, would not be ready for a 64 bit copy of Windows, because you might
need the 64 bit copy of devcon for that. And that requires a separate
acquisition path. Devcon64 is not available in the KB article that
hosts the 32 bit edition.
http://support.microsoft.com/kb/311272
"I386\DevCon.exe 32-bit DevCon tool binary.
This will not function completely on 64-bit Windows.
Ia64\DevCon.exe 64-bit DevCon tool binary. <--- This is for Itanium!!!"
So there is no x64 version of DevCon available there. Despite discussions
and complaints from users about it in the Microsoft web forum, to fix that
damn KB article.
http://social.technet.microsoft.com...ion-of-device-console-utility-devcon-exe.aspx
Whether you attempt a cleanup manually, or use the devcon based batch
file, I recommend a backup first. The Windows 7 System Image is great
for that, as long as you prepare a recovery CD/DVD and know that it is
available to boot the computer. I've restored from a system image twice,
to restore my laptop to a working state.
So the available tools, are less than convenient. And dangerous to use,
as well. (At least "devcon" is. There's no danger from using uvcview,
or from using Linux lsusb for that matter.)
Paul
