# USB interface doesn't work

**URL:** <https://forum.sierrawireless.com/t/usb-interface-doesnt-work/5365>\
**Category:** Development tools\
**Created:** [December 2, 2011, 9:49pm UTC](https://forum.sierrawireless.com/t/usb-interface-doesnt-work/5365 "2011-12-02T21:49:55Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![podreber](https://avatars.discourse-cdn.com/v4/letter/p/c2a13f/32.png) [@podreber](https://forum.sierrawireless.com/u/podreber)\
**Post date:** [December 2, 2011, 9:49pm UTC](https://forum.sierrawireless.com/t/usb-interface-doesnt-work/5365/1 "2011-12-02T21:49:55Z")

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I’m using OpenAT on fastrack xtend and it works well with serial cable but not with USB cable. For some reason “target management” perspective shows “impossible to switch target in development mode” - I do not get this error with serial cable connection, only with USB. This makes debugger not work with USB also.

Please help.

Thanks,  
Sylvester.

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**Author:** ![daav](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/daav/32/2767_2.png) [@daav](https://forum.sierrawireless.com/u/daav)\
**Post date:** [December 5, 2011, 8:00am UTC](https://forum.sierrawireless.com/t/usb-interface-doesnt-work/5365/2 "2011-12-05T08:00:53Z")

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We’re currently facing reliability issues with USB support. A new driver has been developed and will be available soon, which will provide better handling of the target resets and more stability.  
Please stay tuned, it’s a matter of weeks now…

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**Author:** ![tobias](https://avatars.discourse-cdn.com/v4/letter/t/c67d28/32.png) [@tobias](https://forum.sierrawireless.com/u/tobias)\
**Post date:** [December 7, 2011, 1:48pm UTC](https://forum.sierrawireless.com/t/usb-interface-doesnt-work/5365/3 "2011-12-07T13:48:58Z")

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Has the driver issues that appear when assigned COM port number is 100 or higher been solved?

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**Author:** ![daav](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/daav/32/2767_2.png) [@daav](https://forum.sierrawireless.com/u/daav)\
**Post date:** [December 8, 2011, 8:10am UTC](https://forum.sierrawireless.com/t/usb-interface-doesnt-work/5365/4 "2011-12-08T08:10:41Z")

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> [@tobias](#):
>
> Has the driver issues that appear when assigned COM port number is 100 or higher been solved?

Please can you elaborate on this issue?

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**Author:** ![tobias](https://avatars.discourse-cdn.com/v4/letter/t/c67d28/32.png) [@tobias](https://forum.sierrawireless.com/u/tobias)\
**Post date:** [December 8, 2011, 12:11pm UTC](https://forum.sierrawireless.com/t/usb-interface-doesnt-work/5365/5 "2011-12-08T12:11:33Z")

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When connecting to PC via USB, the COM-port number that is assigned to the module may be 100 or more.  
We have found that if the module get COM100 or higher, it’s not possible to open the port.

This was originally found in the old “Wavecom” USB driver, and from what I hear from our clients, it’s still there in Sierra’s USB driver.  
See [viewtopic.php?f=121&t=3990&start=0&hilit=COM100](http://forum.sierrawireless.com/viewtopic.php?f=121&t=3990&start=0&hilit=COM100)

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**Author:** ![daav](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/daav/32/2767_2.png) [@daav](https://forum.sierrawireless.com/u/daav)\
**Post date:** [December 9, 2011, 2:30pm UTC](https://forum.sierrawireless.com/t/usb-interface-doesnt-work/5365/6 "2011-12-09T14:30:45Z")

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Thanks for having highlighted the issue; we didn’t noticed it until now, so it probably won’t be fixed.  
I forward the information to the concerned people.