4 - LabJackUD High-Level Driver [U3 Datasheet] | LabJack
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4 - LabJackUD High-Level Driver [U3 Datasheet]


LabJackUD is the high-level Windows driver for the U3, U6 and UE9. LabJackUD is also referred to as UD and LJUD.

For Linux or Mac OS X, use the Exodriver.

The low-level U3 functions are described in Section 5, but most Windows applications will use the LabJackUD driver instead.

UD Overview Page - Installation Details (Referencable)

Installation Details

The UD library is supported on Windows XP and newer. The archived 3.06 version supports Windows 98, ME, and 2000.

Please install the software before making a USB connection to a LabJack.

The download version of the installer consists of a single executable. This installer places the driver (LabJackUD.dll) in the Windows System directory, along with a support DLL (LabJackWUSB.dll). Generally this is:

  • Windows 98/ME:
    • C:\Windows\System\
  • Windows 2000/XP and 32-bit Windows Vista/7/8/10:
    • C:\Windows\System32\
  • 64-bit Windows Vista/7/8/10:
    • C:\Windows\System32\ (64-bit drivers)
    • C:\Windows\SysWOW64\ (32-bit drivers)

Other files, including the header and Visual C library file, are installed to the LabJack drivers directory. Defaults are:

  • 32-bit Windows:
    • C:\Program Files\LabJack\Drivers\
  • 64-bit Windows:
    • C:\Program Files (x86)\LabJack\Drivers\


Idiot question from newby to U3 on MacOS X 10.6.8.  Installed driver, compiled examples and can run the example programs. Can expand to beginning making my own apps using C. However, it seems I have some high level driver functions contained in the examples (eg eTCConfig, eDAC, etc.) but I don't have others like ResetLabJack, ErrorToString, etc.  Also notice you don't use OpenLabJack in your examples but rather openUSBconnection.  Could not find getCalibrationInfo in U3 user guide.  Compiling with: gcc -lm -llabjackusb u3.o -o myprogram myprogram.c

Puzzled....and confused....

The UD driver and its high-level functions, with a couple of exceptions, are only available on Windows.  The MacOS X driver, Exodriver, is a low-level driver that provides USB communications.  In the examples directory we provide helper functions, such as openUSBConnection and getCalibration, in the u3.c/h, u6.c/h and ue9.c/h files.  Exodriver versions of the easy functions are part of the helper functions, and the only functions ported from the UD driver.  Documentation for the Exodriver and helper functions are in the labjackusb.h and u3.h header files.  The README file provides information on the Exodriver and what is included in the package.


Are there any functions that I can use to check the device is still connected (like a ping function). I just want to pass a handle id to the function if possible.