**Read the docs at http://emodbus.github.io!**  This is a library to provide Modbus client (formerly known as master), server (formerly slave) and bridge/gateway functionalities for Modbus RTU, ASCII and TCP protocols. For Modbus protocol specifications, please refer to the [Modbus.org site](https://www.modbus.org/specs.php)! Modbus communication is done in separate tasks, so Modbus requests and responses are non-blocking. Callbacks are provided to prepare or receive the responses asynchronously. Key features: - for use in the Arduino framework - designed for ESP32, various interfaces supported; async versions run also on ESP8266 - non blocking / asynchronous API - server, client and bridge modes - TCP (Ethernet, WiFi and Async), ASCII and RTU interfaces - all common and user-defined Modbus standard function codes This has been developed by enthusiasts. While we do our utmost best to make robust software, do not expect any bullet-proof, industry deployable, guaranteed software. [**See the license**](https://github.com/eModbus/eModbus/blob/master/license.md) to learn about liabilities etc. We do welcome any ideas, suggestions, bug reports or questions. Please use the "[Issues](https://github.com/eModbus/eModbus/issues)" tab to report bugs and request new features and visit the "[Discussions](https://github.com/eModbus/eModbus/discussions)" tab for all else. Have fun!