couldn't connect to my ue9 using usb in linux platform NEED HELP | LabJack
LabJack is closed July 3 to July 5 for the Independence Day holiday.

couldn't connect to my ue9 using usb in linux platform NEED HELP

6 posts / 0 new
Last post
kevin21's picture
couldn't connect to my ue9 using usb in linux platform NEED HELP

[email protected]-desktop:~/Desktop$ python

Python 2.7.12 (default, Nov 19 2016, 06:48:10) 

[GCC 5.4.0 20160609] on linux2

Type "help", "copyright", "credits" or "license" for more information.

>>> import ue9

>>> d = ue9.UE9()

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

  File "build/bdist.linux-armv7l/egg/", line 92, in __init__

    Args: firstFound, Open the first found UE9

  File "build/bdist.linux-armv7l/egg/", line 111, in open

    Subnet = None, PortA = None, PortB = None, DHCPEnabled = None)

  File "build/bdist.linux-armv7l/egg/", line 607, in open


  File "build/bdist.linux-armv7l/egg/", line 1352, in openLabJack

    raise NullHandleException()

  File "build/bdist.linux-armv7l/egg/", line 1248, in _openLabJackUsingExodriver


LabJackPython.NullHandleException: Couldn't open device. Please check that the device you are trying to open is connected.

LabJack Support
LabJack Support's picture
First power cycle (USB

First power cycle (USB disconnect and reconnect) your device and try the open call again.

Second, make sure no other application has your UE9 open. Only one application can claim a USB handle to the device at a time.

Third, make sure your UE9's power LED is on. This indicates the UE9 has power and is enumerated on your system. Also, you can run the "lsusb" command to see if Linux is detecting it is connected. The UE9's vendor ID is 0x0CD5 (hex value) and the product ID is 9. If your UE9 is not being detected or powered when connected over USB, try a different USB port.

kevin21's picture
Hi,Support team 

Hi,Support team 

thanks it works well with your advise.



m. corus
m. corus's picture
Hi everyone,

Hi everyone,

I'm facing the same issue, running under linux (Debian based). libusb-1.0, exodriver and LabjackPython have been installed, whithout error (or without me seeing them).


What I tried :

* Plug in each USB port, and check that the led is on. It flashes for a second or two,  and it stays on each time.

* Tried it after several reboot, assuming it would kill any other call to the device (U3-HV). I call them only once.

* Tried to unplug and replug in the same port, and different ports

* lsusb indicates that labjack is plugged


And I still have the same error :

LabJackPython.NullHandleException: Couldn't open device. Device access or claim error. Please check that the device is not already open in another or the current process.


I tried to go a bit further, to catch the error, and used the functions to catch the error. I could check that :

* device is recognized : staticLib.LJUSB_GetDevCount(3) gives 1

* ctypes.get_errno() gives 13  (got 11 once, yesterday...)


Any clue would be welcome...



LabJack Support
LabJack Support's picture
13 is EACCES: Permission

13 is EACCES: Permission denied.

If you run the program with sudo, does it work?

LabJack Support
LabJack Support's picture
If you haven't already, you

If you haven't already, you should restart the udev rules:

sudo udevadm control --reload-rules

For more detials, see "To Reload the udev Rules" in: