libmodbus is a free software library to send/receive data with a device which respects the Modbus protocol. This library can use a serial port or an Ethernet connection.
The functions included in the library have been derived from the Modicon Modbus Protocol Reference Guide which can be obtained from www.modbus.org.
The license of libmodbus is LGPL v2.1 or later.
The documentation is available as manual pages (man libmodbus to read general
description and list of available functions) or Web pages
www.libmodbus.org/documentation/. The
documentation is licensed under the Creative Commons Attribution-ShareAlike
License 3.0 (Unported) (http://creativecommons.org/licenses/by-sa/3.0/).
The official website is www.libmodbus.org.
While the library is written in C and designed to run on Linux, Mac OS X, FreeBSD and QNX and Windows, this repository contains a modified version which allows for FreeRTOS implementation and is tested on ESP32 based IoT device.