# tokio-modbus A pure [Rust](https://www.rust-lang.org) [Modbus](https://en.wikipedia.org/wiki/Modbus) library based on [tokio](https://tokio.rs). [](https://crates.io/crates/tokio-modbus) [](https://docs.rs/tokio-modbus/) [](https://github.com/slowtec/tokio-modbus/actions/workflows/security-audit.yaml) [](https://github.com/slowtec/tokio-modbus/actions/workflows/build-and-test.yaml) [](./LICENSE-MIT) [](./LICENSE-APACHE) Modbus is based on a [_master/slave_]() communication pattern. To avoid confusion with the Tokio terminology the _master_ is called _client_ and the _slave_ is called _server_ in this library. ## Features - Pure Rust library - Modbus TCP or RTU at your choice - Both `async` (non-blocking, default) and `sync` (blocking, optional) - Client API - Server implementations - for _out-of-the-box_ usage or - as a starting point for a customized implementation - Open source (MIT/Apache-2.0) ## Installation Add this to your `Cargo.toml`: ```toml [dependencies] tokio-modbus = "*" ``` ### Cargo Features - `"rtu"`: Asynchronous RTU client (default) - `"tcp"`: Asynchronous TCP client (default) - `"rtu-sync`: Synchronous RTU client - `"tcp-sync"`: Synchronous TCP client - `"rtu-server"`: (Asynchronous) RTU server - `"tcp-server"`: (Asynchronous) TCP server - `"rtu-over-tcp-server"`: (Asynchronous) RTU over TCP server #### Examples If you only need an asynchronous TCP client add the following line to your Cargo.toml file: ```toml [dependencies] tokio-modbus = { version = "*", default-features = false, features = ["tcp"] } ``` For an asynchronous RTU client: ```toml [dependencies] tokio-modbus = { version = "*", default-features = false, features = ["rtu"] } ``` For an RTU server: ```toml [dependencies] tokio-modbus = { version = "*", default-features = false, features = ["rtu-server"] } ``` For a TCP server: ```toml [dependencies] tokio-modbus = { version = "*", default-features = false, features = ["tcp-server"] } ``` ## Examples Various examples for Modbus RTU and TCP using either the asynchronous or synchronous API can be found in the [examples](https://github.com/slowtec/tokio-modbus/tree/main/examples) folder. ## Testing The workspace contains documentation, tests, and examples for all available features. ```sh cargo test --workspace cargo test --workspace --all-features ``` ## Protocol-Specification - [Modbus Application Protocol Specification v1.1b3 (PDF)](http://modbus.org/docs/Modbus_Application_Protocol_V1_1b3.pdf) - [Modbus over serial line specification and implementation guide v1.02 (PDF)](http://modbus.org/docs/Modbus_over_serial_line_V1_02.pdf) - [Modbus Messaging on TCP/IP Implementation Guide v1.0b (PDF)](http://modbus.org/docs/Modbus_Messaging_Implementation_Guide_V1_0b.pdf) ## License Copyright (c) 2017-2024 [slowtec GmbH](https://www.slowtec.de) [MIT](LICENSES/MIT.txt)/[Apache-2.0](LICENSES/Apache-2.0.txt)