What is LJM?

LJM is LabJack's free, cross-platform driver / library for simplifying device communication. It supports the LabJack T4 and T7 series and T8 devices.

Download

See the LJM installer page to download.

Documentation

See the LJM User's Guide.

Features

• Cross-platform
• Supported in multiple languages
• Completely free
• Licensed with the permissive MIT X11 License
• Well-documented User's Guide
• Device discovery
• Device reconnection—automatically repairs connections
• Modbus Name-To-Address interpretation - ability to interpret LabJack register names such as "AIN0"
• Error-To-String Interpretation
• Utility functions to:
  • Convert bytes to values
  • Perform thermocouple calculations
  • Convert IP and MAC numbers
• Versatile Library configurations
• Threaded data streaming and buffering
• Thread-safe
• Basic demo mode for testing without a physical device.

Cross-Platform

Support for Windows, macOS, and Linux allows for the same code to be run on different operating systems with the same results, whether it's on your Windows desktop, MacBook laptop, or Raspberry Pi running a distribution of Linux.

Supported In Multiple Languages

Written in C++ with a C API, LabJack maintains and supports wrappers for many programing languages.

using LabJack;

    ...

    int handle;
    LJM.OpenS("T7", "USB", "ANY", ref handle);

    // Read the voltage on AIN0
    double voltage;
    LJM.eReadName(handle, "AIN0", ref voltage);

    ...

Some other supported languages:

• LabVIEW
• Visual Basic .NET
• DAQFactory
• See the full list of supported languages.

LJM's API allows for easy integration into most languages. If the language you use isn't currently supported, feel free to contact us for assistance in integrating LJM into your project.

LJM Is For Any Level Of Expertise

You don't need to be familiar with Modbus to use LJM. Simply use LJM's Easy Functions for direct access to all the features your LabJack device provides.

If you do prefer to use Modbus, LJM's Raw Byte Functions provide byte-level control to manually send and receive Modbus packets.