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API Documentation

LJM Library - T-series and Digit devices

LJM is a free, cross-platform driver/library for simplifying device communication. It supports the LabJack T-Series devices and Digit devices on Windows, Linux, and macOS.

Modbus TCP - T-Series devices and UE9

T-series and UE9 devices are Modbus TCP Servers. Software and devices that can act as a Modbus TCP Client can talk directly to a Modbus Server over a TCP/IP connection such as Ethernet or WiFi.

UD Library - Windows only library for U3, U6, UE9

The UD library is the Windows driver/library for the U3, U6 and UE9. UD is also referred to as LabJackUD and LJUD.

Exodriver - macOS and Linux library for U3, U6, UE9, U12

The Exodriver is used to communicate over USB with the LabJack U3, U6, UE9 and U12 in Mac OS X and Linux environments.  Other APIs and examples on Mac OS X and Linux such as the LabJackPython for Python and ljacklm for the U12 require the Exodriver.

The Exodriver function documentation can be found in the labjackusb.h header file. See the Low Level UD User's Guide for other useful information.

U12 Library (ljackuw and ljacklm) - U12

ljackuw is the high level library for the U12 on Windows. ljacklm is a port of ljackuw for macOS and Linux.

Recommended Software

Though LabJack devices can be used with a variety of software options, we recommend the following—unless you already know what software you'd like to use.

If you'd like a graphical application for device configuration or basic data collection, see the available LabJack applications.

If you'd like to write a program for custom behavior, LabJack recommends the following:


Windows, Linux, and macOS: LJM library (C/C++) or any LJM language wrapper.

For the full list, see the T-series software options.

U3, U6, and UE9


Linux and macOS:

For the full list, see the UD software options.



Linux and macOS:


Windows: Otero

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