4 - LabJackUD High-Level Driver [U6 Datasheet] | LabJack
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4 - LabJackUD High-Level Driver [U6 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 U6 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\


What does UD stand for and what is the difference bewteen Modbus and UD?

UD had some internal meaning during development, but really does not stand for anything.  The UD library is the high-level Windows library for the U3, U6, and UE9.

Consider that there is a low-level protocol and high-level library.  The low-level protocol describes the actual packets going back and forth to the device.  The high-level library provides a higher-level API to applications, and underneath uses the low-level protocol to talk to the device.

The U3/U6/UE9 speak the same low-level protocol.  It is a proprietary protocol and is described in Section 5.

The high-level library for the U3/U6/UE9 is the UD library which is described here in Section 4, and we provide UD examples for many languages.

The new T7 speaks Modbus TCP as its low-level protocol, and the new high-level LJM library is provided for Linux/Mac/Windows.

Awesome, thanks for the super quick and clear response.