Easy Modbus

A Rust Modbus library.

Examples

A simple Modbus TCP Server:

use std::error::Error;

use futures::SinkExt;
use tokio::net::{TcpListener, TcpStream};
use tokio_stream::StreamExt;
use tokio_util::codec::Framed;

use easy_modbus::{Frame, codec::TcpServerCodec};

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let addr = "127.0.0.1:502".to_string();
    let server = TcpListener::bind(&addr).await?;
    println!("Listening on: {}", addr);

    loop {
        let (stream, _) = server.accept().await?;
        tokio::spawn(async move {
            if let Err(e) = process(stream).await {
                println!("failed to  process connection; error = {}", e);
            }
        });
    }
}

async fn process(stream: TcpStream) -> Result<(), Box<dyn Error>> {
    let mut transport = Framed::new(stream, TcpServerCodec);
    let frame = Frame::tcp();
    while let Some(request) = transport.next().await {
        match request {
            Ok(request) => {
                println!("load request --- {:?}", request);
                let response = frame.read_coils_response(0x01, vec![0x00, 0x01]);
                println!("send response --- {:?}", response);
                transport.send(response).await?;
            }
            Err(e) => return Err(e.into()),
        }
    }
    Ok(())
}

A simple Modbus TCP Client:

use std::error::Error;

use futures::SinkExt;
use tokio::net::TcpStream;
use tokio_stream::StreamExt;
use tokio_util::codec::Framed;

use easy_modbus::{Frame, codec::TcpClientCodec};

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let addr = "127.0.0.1:502".to_string();
    let stream = TcpStream::connect(&addr).await?;
    let mut transport = Framed::new(stream, TcpClientCodec);
    let frame = Frame::tcp();
    let request = frame.read_coils_request(0x01, 0x02, 0x08);
    println!("{}", request);
    transport.send(request).await?;
    while let Some(response) = transport.next().await {
        return match response {
            Ok(response) => {
                println!("{}", response);
                Ok(())
            }
            Err(e) => {
                Err(e.into())
            }
        }
    }
    Ok(())
}

A simple Modbus RTU Client:

use futures::{SinkExt, StreamExt};
use tokio_serial::SerialStream;
use tokio_util::codec::Framed;
use easy_modbus::{Frame, Response};
use easy_modbus::codec::RtuClientCodec;
#[tokio::main(flavor = "current_thread")]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let tty_path = "COM4";
    let rate = 9600;
    let slave = 0x01;
    let serial_builder = tokio_serial::new(tty_path, rate);
    let port = SerialStream::open(&serial_builder).unwrap();
    let mut transport = Framed::new(port, RtuClientCodec);
    let frame = Frame::rtu();
    let request = frame.read_multiple_holding_registers_request(slave, 0x00, 0x02);
    println!("Request:\t{}", request);
    transport.send(request).await?;
    while let Some(response) = transport.next().await {
        match response {
            Ok(response) => {
                println!("Response:\t{}", response);
                match response {
                    Response::ReadMultipleHoldingRegisters(_, res) => {
                        let a = res.get_values();
                        let h = ((a[0] as u16 * 256) + a[1] as u16) as f64 / 10.0;
                        let t = ((a[2] as u16 * 256) + a[3] as u16) as f64 / 10.0;
                        println!("h {} t {}", h, t);
                        return Ok(())
                    }
                    _ => {
                        println!("unknown")
                    }
                }
            }
            Err(e) => {
                return Err(e.into());
            }
        }
    }
    Ok(())
}

Source Code Mirror

sourcehut

License

This project is licensed under the MIT license.