Madbus

A Rust library for Modbus TCP communication.
It provides simple APIs for building both Modbus clients (masters) and servers (slaves) with automatic encoding/decoding of Modbus TCP frames.

Features

• Modbus TCP Client and Server utilities
• Automatic MBAP header handling
• Encoding/decoding of Modbus ADU/PDU
• Built-in exception handling
• Helper utilities for bit packing/unpacking
• Supports common Modbus function codes:
  • 0x01 Read Coils
  • 0x02 Read Discrete Inputs
  • 0x03 Read Holding Registers
  • 0x04 Read Input Registers
  • 0x05 Write Single Coil
  • 0x06 Write Single Register
  • 0x0F Write Multiple Coils
  • 0x10 Write Multiple Registers

Project Structure

src/
├── main.rs              # Client/Server implementation and ADU handling
├── function_codes.rs    # Commands and responses
├── exception_codes.rs   # Modbus exception definitions
└── helpers.rs           # Utility helpers

Usage

Client Example

Send a request to a Modbus device:

use madbus::{Client, Command};
use std::net::TcpStream;

let mut stream = TcpStream::connect("127.0.0.1:502").unwrap();

let cmd = Command::ReadHolding {
    start: 0,
    count: 5
};

Client::send_request(&mut stream, cmd, 1).unwrap();

Read the response:

let (response, unit_id, transaction_id) =
    Client::read_response(&mut stream).unwrap();

println!("{:?}", response);

Server Example

Reading a request from a client:

use madbus::Server;

let (command, unit_id, transaction_id) =
    Server::read_request(&mut stream).unwrap();

Sending a response:

use madbus::Response;

let response = Response::read_holding(&[10, 20, 30]);

Server::send_resp(&mut stream, response, unit_id, transaction_id).unwrap();

Sending an exception:

use madbus::Exception;

Server::send_exception(
    &mut stream,
    Exception::IllegalAddress,
    3,
    unit_id,
    transaction_id
).unwrap();

Testing

cargo test

License

MIT