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Modbus Client Applications

LabJack T-series devices are Modbus TCP servers. Any Modbus TCP Client should be able to talk to our T-series devices. This page provides a list of client applications that claim to support Modbus TCP communications.

We have not tested every client listed below.

Getting Started

T-series devices have several test registers that should be used before trying to read or write other device registers. This will help debug any configuration issues with addressing or bit-wise (byte-flipping). See our Getting Started Guide.

Modbus Map

The Modbus Map defines the address and name of all registers used with T-series devices, along with other information.

Existing Modbus Client Applications

Open PLC (Free, Open Source)

Open PLC is an open source PLC software suite that has been built to function on an industrial and home automation level. It has been put together by a PhD student Thiago Rodrigues Alves and according to his website consists of three parts: Runtime, Editor, and HMI builder. The HMI builder (ScadaBR) portion of the project can be used to directly interface with LabJack T-Series devices. The other applications can also be used to utilize LabJack devices.

pvbrowser (Free, Open Source)

pvbrowser is an open source HMI/SCADA/DCS project whose code is available on GitHub. The project started in 2000 and is a fairly mature project that enables users to create client-server architectured open source SCADA systems and HMIs. pvbrowser at its core is a client-server uses QT at its core to enable users to create customized SCADA system servers (install the PV development package) that can connect to multiple Modbus TCP slave devices, collect data, and then report data using their pvbrowser (client) application. Both the client and server portions can be run on multiple operating systems: Windows, Linux, macOS, and others (downloads page). There is a great introductory example on their examples page. Essentially, go to their downloads page, download the appropriate client application, and instruct it to connect to their demo server "pv://

ScadaBR (Free, Open Source)

ScadaBR is a project that started in 2006 and has been working on an open source free software platform that communicates with Modbus TCP devices and allows users to create customizable HMI screens for Automation, Data Acquisition, and Supervisory Control applications. This application is featured in the OpenPLC project, and has a v2.0 or an -LTS version in the works that looks quite promising.

Node-Red (Free, Open Source)

Node-RED is a powerful high-level GUI based programming language (much like LabVIEW) that can be run on a Raspberry Pi. Here is a good Raspberry Pi + Node-RED + Modbus TCP + MQTT tutorial video on YouTube.

Additional resources:

  • On the T4 forum a customer was able to integrate a T4 with Node-RED. The topic discusses things like big vs little endian data formatting as well as some other Node-RED basics. Polling T4 Temperature_AIR_K

  • Creating dashboards with node-red using the node-red-dashboard library.

  • Brain Boxes has a published tutorial for how to configure the Node-RED modbus read and write nodes in their FAQ: Using Modbus TCP with Node-RED

SCADA-LTS (Free and Paid, Open Source)

SCADA-LTS new and potentially up-and-coming SCADA application that is developed in Java, is open source, and features a GUI builder that may be worth checking out.

PyScada (Free, Open Source)

PyScada is an open source application built using Python and features a modern HTML5 based HMI. It has very low hardware requirements for the server and is completely open source. They have great documentation and their code is available on GitHub PyScada.

Infinite Automation (Paid, Contracted SCADA System Development)

Infinite Automation produces a Building Automation, Data Acquisition, IIoT, or SCADA application called Mango Automation that has a free version as well as multiple paid option and advertises many great features from protocol choices to HMI pages and data logging. They also have an open source Modbus library written in Java that can be downloaded free of charge from their website called Modbus4J.

mySCADA (paid, contracting available)

mySCADA produces a device agnostic SCADA system with a lot of options for logging, controlling, and HMI development. If you are looking for a company to help you make a customized solution to automate your lab, factory, etc, take a look at this company and pair their application with powerful T-Series DAQ devices.

IGSS (Free to 50 channels)

IGSS is an application produced by schneider electric that has a free version that supports up to 50 objects/tags and allows you to use a generic Modbus TCP driver (ID:64) to collect data from generic PLC equipment like LabJack T-Series devices (T4,T7).

Advanced HMI (Custom HMI development, paid)

Advanced HMI is a company that produces industrial panel PCs that run windows and produces a free HMI software package that has support for Modbus TCP devices. There is a simple video tutorial posted on their SourceForge page.


OpenSCADA Is project that has been around since 2006 and is maintained by some folks in Ukraine. It looks like they have had some active development in 2018 and their SCADA software supports a large number of Linux distributions and single board computer hardware platforms.


OpenAPC (Open Advanced Process Control) Is project that has been around for quite a while and offers a platform independent HMI/PLC/SCADA application that runs on macOS, Windows, and Linux.

Simply Modbus TCP (Free and Paid Options, old school look)

Simply Modbus is a very simple Modbus TCP test and log program that has existed for many years. They have a webpage that describes Modbus TCP (the protocol) and they have a free demo Modbus TCP Client application available and offer paid license options for going further.

Modbus Tools (Free and Paid)

Modbus Tools is another simple Modbus TCP test and log program/API suite that has existed for many years. They have a free demo available and offer paid license options for going further. They offer a 3rd party option to our LJM library for a programmatic interface to Modbus TCP devices and they also offer an Active X plugin for Excel.

TCP Modbus Examiner tool (Free, source code available)

The TCP Modbus Examiner tool is a simple tool that communicates with Modbus TCP devices developed using WPF that illustrates the simplicity and usefulness of using the Modbus TCP protocol for data acquisition applications.

AzeoTech QuickMod (free download)

We got this to work easily.  Do the following to start reading FIO0-FIO3: Start => Programs => DAQFactory => Samples => QuickMod Modbus Scanner:

  • Select Modbus TCP over Ethernet.

  • Click Configure, set IP Address to the correct value, and set Port = 502.

  • Change Tag # = 2000.

Chipkin CAS Modbus Scanner (free download)

We got this to work easily, but noticed all 3 quirks above.

Steps to read FIO0-FIO3:

  • Add a TCP connection with proper IP and port 502.

  • Add a device with ID 1.

  • Add a request with Function #3, Offset=2001, and Length=4.

  • Go back to the main screen, select that task/request, and click "Poll".

Rockwell / Allen-Bradley PLC

A customer reported success with an EN2T module specifically, and others have reported success with Allen-Bradley PLCs in general.  Reference technote 470365 (from Rockwell Automation or Allen-Bradley).

Maple Systems 5070TH, Weintek MT8070iH, EasyBuilder Pro

A customer told us that the 5070TH and MT8070iH are the same HMI.  EasyBuilder Pro software is a free download, and has a simulator that can be used for testing.  While helping the customer we did get EasyBuilder Pro to work ourselves, and made the following obscure notes for someone who knows nothing about the software:

  • To change settings for the LabJack, go to Edit => System Parameters.

  • To change settings for the Numeric Display Object, click on it, then right-click and go to Attributes.

  • To make it go, click on On-Line Simulation.

We noticed that this client had quirks #1 and #2 from the list at the top of this page.  To handle #2, EasyBuilder provides a function called SWAPW that the customer used successfully.


A customer reported success with Wonderware.  They reported that it had all 3 quirks from the list at the top of this page, and in fact they had to request address 40001 to get it to read address 0.

More SCADA software can be found through Google searches and these links:

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