Re: [pyusb-users] Error doing control transfer

[vvyogi . <vv...@gm...>]

Python is not finding the libusb-win32.dll file, you could put it

inside the python interpreter directory just for tests


The directory *C:\Python27\DLLs* contains* libusb0.dll*, this same file is
also there in *C:\Windows\System32* directory.
I removed the *dll* from *C:\Python27\DLLs *and I ran my program, it gave
the same error log( as if removing the *dll* made no difference). Does this
means that pyUsb is using backend from system32(or I am looking at the
wrong directory).

2013-10-03 10:32:16,684 INFO:usb.core:find(): using backend
>> "usb.backend.libusb10"
>
> 2013-10-03 10:32:16,684
>> DEBUG:usb.backend.libusb10:_LibUSB.enumerate_devices()
>
> 2013-10-03 10:32:16,749
>> DEBUG:usb.backend.libusb10:_LibUSB.get_device_descriptor(<usb.backend.libusb10._Device
>> object at 0x01841AF0>)
>
> 2013-10-03 10:32:16,750
>> DEBUG:usb.backend.libusb10:_LibUSB.get_device_descriptor(<usb.backend.libusb10._Device
>> object at 0x01841B70>)
>
> 2013-10-03 10:32:16,750
>> DEBUG:usb.backend.libusb10:_LibUSB.get_device_descriptor(<usb.backend.libusb10._Device
>> object at 0x01841B30>)
>
> 2013-10-03 10:32:16,750
>> DEBUG:usb.backend.libusb10:_LibUSB.get_device_descriptor(<usb.backend.libusb10._Device
>> object at 0x01841B90>)
>
> 2013-10-03 10:32:16,750
>> DEBUG:usb.backend.libusb10:_LibUSB.get_device_descriptor(<usb.backend.libusb10._Device
>> object at 0x01841AF0>)
>
> 2013-10-03 10:32:16,750
>> DEBUG:usb.backend.libusb10:_LibUSB.get_device_descriptor(<usb.backend.libusb10._Device
>> object at 0x01841B70>)
>
> 2013-10-03 10:32:16,750
>> DEBUG:usb.backend.libusb10:_LibUSB.get_device_descriptor(<usb.backend.libusb10._Device
>> object at 0x01841B30>)
>
> 2013-10-03 10:32:16,752
>> DEBUG:usb.backend.libusb10:_LibUSB.get_configuration_descriptor(<usb.backend.libusb10._Device
>> object at 0x01841B30>, 0)
>
> 2013-10-03 10:32:16,752
>> DEBUG:usb.backend.libusb10:_LibUSB.open_device(<usb.backend.libusb10._Device
>> object at 0x01841B30>)
>
> 2013-10-03 10:32:16,752
>> DEBUG:usb.backend.libusb10:_LibUSB.set_configuration(c_void_p(31461336), 1)
>
> VUSB_HID Device Found
>
> 1
>
> 255
>
> 18
>
> Traceback (most recent call last):
>
>   File "myu.py", line 24, in <module>
>
>     dev.set_configuration()
>
>   File "C:\Python27\lib\site-packages\usb\core.py", line 547, in
>> set_configuration
>
>     self._ctx.managed_set_configuration(self, configuration)
>
>   File "C:\Python27\lib\site-packages\usb\core.py", line 92, in
>> managed_set_configuration
>
>     self.backend.set_configuration(self.handle, cfg.bConfigurationValue)
>
>   File "C:\Python27\lib\site-packages\usb\_debug.py", line 60, in do_trace
>
>     return f(*args, **named_args)
>
>   File "C:\Python27\lib\site-packages\usb\backend\libusb10.py", line 503,
>> in set_configuration
>
>     _check(_lib.libusb_set_configuration(dev_handle, config_value))
>
>   File "C:\Python27\lib\site-packages\usb\backend\libusb10.py", line 403,
>> in _check
>
>     raise USBError(_str_error[ret], ret, _libusb_errno[ret])
>
> usb.core.USBError: [Errno 2] Entity not found
>
> 2013-10-03 10:32:16,769
>> DEBUG:usb.backend.libusb10:_LibUSB.close_device(c_void_p(31461336))
>
>
Now about the libusb-win32.dll, I couldn't locate this dll.
In the libusb-win32 distribution there i a *libusb0_x86.dll, *is this the
required dll that I need to put in *C:\Python27\DLLs *?
Kindly suggest where to look for the dll and where to put it ?

Thanks and Regards
Vivek




On Thu, Oct 3, 2013 at 1:41 AM, Wander Lairson Costa <
wan...@gm...> wrote:

> 2013/10/2 Vivek Yogi <vv...@gm...>:
> > I did installed the pyUsb via the usual python package installation
> method i.e.
> >
> >>python setup.py install
> >
> > As for the libusb, I didn't install any binary or any python setup for
> it.
> >
> > For the device(a vUsb device) I had to install the driver using the
> inf-wizard.exe available with libusb-win32 distribution.
> >
> > Thats all I did for the python end.
> >
> > For C# application I had to use reference to libUsbDotNet.dll
> >
>
> Python is not finding the libusb-win32.dll file, you could put it
> inside the python interpreter directory just for tests.
>
> --
> Best Regards,
> Wander Lairson Costa
>
>
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