Crate tokio_modbus

tokio-modbus

A pure Rust Modbus library based on tokio.

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:

[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:

[dependencies]
tokio-modbus = { version = "*", default-features = false, features = ["tcp"] }

For an asynchronous RTU client:

[dependencies]
tokio-modbus = { version = "*", default-features = false, features = ["rtu"] }

For an RTU server:

[dependencies]
tokio-modbus = { version = "*", default-features = false, features = ["rtu-server"] }

For a TCP server:

[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 folder.

Testing

The workspace contains documentation, tests, and examples for all available features.

cargo test --workspace
cargo test --workspace --all-features

Protocol-Specification

• Modbus Application Protocol Specification v1.1b3 (PDF)
• Modbus over serial line specification and implementation guide v1.02 (PDF)
• Modbus Messaging on TCP/IP Implementation Guide v1.0b (PDF)

License

Copyright (c) 2017-2024 slowtec GmbH

MIT/Apache-2.0

Re-exports

pub use self::slave::Slave;

pub use self::slave::SlaveId;

pub use bytes;

Modules

client

Modbus clients

prelude

Common types and traits

server

Modbus server skeletons

slave

Modbus devices

Structs

ExceptionResponse

A server (slave) exception response.

SlaveRequest

A Modbus request with slave included

Enums

Error

Protocol or transport errors.

ExceptionCode

A server (slave) exception.

FunctionCode

A Modbus function code.

ProtocolError

Modbus protocol error.

Request

A request represents a message from the client (master) to the server (slave).

Response

The data of a successful request.

Type Aliases

Address

A Modbus protocol address is represented by 16 bit from 0 to 65535.

Quantity

Number of items to process.

Result

Specialized std::result::Result type for type-checked responses of the Modbus client API.