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Agilent 34461A DMM - Pyusb No Langid and Entity Not found

Question asked by spidermonkey1187 on Jun 21, 2017

This question is also posted on stackoverflow.com but it's been about 11 days and no answer has been presented.  I am using the python PL.  The 34461A is connected directly to my computer via USB, I have installed the PyUSB libraries and USBTMC. 

 

When I try to search for the device it can be found via python but Entity Not Found is raised.  The Keysight Connection Expert finds it and commands it just fine.  The below is a small piece of code that I entered into the python console just to test this and still get that error. 

 

import usb.core
from usb import core
from dw_libs import usbtmc
dev = usbtmc.some_instrument(usbtmc.AGILENT_34461A)

Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "P:\Diasemi\scripts\dw_libs\usbtmc.py", line 31, in __init__
    if self.usb_dev.is_kernel_driver_active(0):
  File "P:\Python27\lib\site-packages\usb\core.py", line 1061, in is_kernel_driver_active
    self._ctx.managed_open()
  File "P:\Python27\lib\site-packages\usb\core.py", line 102, in wrapper
    return f(self, *args, **kwargs)
  File "P:\Python27\lib\site-packages\usb\core.py", line 120, in managed_open
    self.handle = self.backend.open_device(self.dev)
  File "P:\Python27\lib\site-packages\usb\backend\libusb1.py", line 786, in open_device
    return _DeviceHandle(dev)
  File "P:\Python27\lib\site-packages\usb\backend\libusb1.py", line 643, in __init__
    _check(_lib.libusb_open(self.devid, byref(self.handle)))
  File "P:\Python27\lib\site-packages\usb\backend\libusb1.py", line 595, in _check
    raise USBError(_strerror(ret), ret, _libusb_errno[ret])
USBError: [Errno 2] Entity not found

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