Direct Modbus TCP Examples | LabJack
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Direct Modbus TCP Examples

Direct Modbus TCP

Direct Modbus TCP Overview

Because the T7 and T4 transmit all of their information using Modbus TCP, they are compatable with dozens of 3rd party libraries. If we don't support a particular language required for an application, try searching for a Modbus TCP library that is compatible with your language of choice. The following is a list of libraries that we have successfully used to communicate with our devices using Modbus TCP.

Getting Started

The T7 and T4 have five test registers that should be used before trying to read/write to other registers. This will help in trying to debug any getting-started related issues with addressing or bit-wise (byte-flipping) issues.

Modbus Map

The Modbus Map defines the address and name of all registers, along with other information.  This section has a dynamic map that allows you to filter and search.

Direct Modbus API Documentation

For more information about LabJack's Direct Modbus implementation check out the API documentation section.

Modbus TCP Example Code Table

Modbus TCP Example Code Table (Referencable)

Direct Modbus TCP Example Code

T7 T4

T7, T4

Libraries... Windows Mac Linux
C/C++ (Streaming)

To use a 3rd party Modbus program, such as a Rockwell/Allen Bradley application, there is no download - simply follow the instructions on the Modbus Client Applications page.

More information about Modbus as well as some getting started information can be found on the Modbus API Documentation page. A list of the available Modbus registers that the T7 supports is available on the Modbus Map page.