[pyusb-users] USB Control Message Error

Xiaofan Chen

2015-09-08 09:05:40 UTC

On Tue, Sep 8, 2015 at 8:58 AM, Srinidhi Kuntaegowdanahalli

Post by Srinidhi Kuntaegowdanahalli
I am new to python and I am using pyDAQFlex to interface with an USB DAQ
from Measurement Computing.
pyDAQFlex uses pyUSB. I have installed "libusb-win32-filter-bin-0.1.12.1"

That is super outdated and no longer supported. Unless you are using
Windows 98/ME, you should not use this old version of libusb-win32.

Latest version is 1.2.6.0.
Web site: http://sourceforge.net/projects/libusb-win32/files/libusb-win32-releases/1.2.6.0/

Post by Srinidhi Kuntaegowdanahalli
and I am able to see my DAQ through the GUI which pops up after
installation. When I run the test code for pyDAQFlex, I get the following
File "C:\Python25\lib\site-packages\daqflex\devices.py", line 234, in
__get_in
terface
alternate_setting = usb.control.get_interface(self.dev, intf_number)
File "build\bdist.win32\egg\usb\control.py", line 244, in get_interface
File "build\bdist.win32\egg\usb\core.py", line 971, in ctrl_transfer
File "build\bdist.win32\egg\usb\backend\libusb0.py", line 528, in
ctrl_transfe
r
File "build\bdist.win32\egg\usb\backend\libusb0.py", line 380, in _check
usb.core.USBError: [Errno None] usb_control_msg: sending control message
failed,
win error: The request is not supported.
The last line seems to indicate that this is an issue with pyUSB
rather than the DAQflex module.

Why do you say so? This means that you are sending a control
message wrongly -- most likely the device does not understand
your command. Do you have the USB communication protocol
of your DAQ?

--
Xiaofan

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