Struct Master 

pub struct Master { /* private fields */ }

Blocking Modbus RTU master that enforces Modbus idle timing rules between frames.

Implementations

impl Master

pub fn new_rs485(path: &str, baud_rate: u32) -> Result<Self>

Builds a master configured for an RS-485 style setup (8N1, blocking I/O).

The port timeout is pinned to the Modbus RTU silent interval (T3.5) for the supplied baud rate so that the reader can detect frame boundaries.

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Examples

use modbus_rtu::Master;

let master = Master::new_rs485("/dev/ttyUSB0", 9_600)?;
assert_eq!(master.baud_rate(), 9_600);

pub fn baud_rate(&self) -> u32

Returns the baud rate currently configured on the serial link.

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Examples

use modbus_rtu::Master;

let master = Master::new_rs485("/dev/ttyUSB0", 38_400)?;
assert_eq!(master.baud_rate(), 38_400);

pub fn set_baudrate(&mut self, baud_rate: u32) -> Result<()>

Updates the serial baud rate and matching Modbus idle timeout.

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Examples

use modbus_rtu::Master;

let mut master = Master::new_rs485("/dev/ttyUSB0", 9_600)?;
master.set_baudrate(19_200)?;
assert_eq!(master.baud_rate(), 19_200);

pub fn send(&mut self, req: &Request<'_>) -> Result<Response, Error>

Sends a Modbus RTU request and waits for the corresponding response.

Broadcast requests return immediately after the frame is flushed because the Modbus RTU spec forbids responses to slave id 0.

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Examples

use modbus_rtu::{Function, Master, Request};

let mut master = Master::new_rs485("/dev/ttyUSB0", 19_200)?;
let func = Function::ReadHoldingRegisters { starting_address: 0x0000, quantity: 2 };
let request = Request::new(0x01, &func, std::time::Duration::from_millis(200));
let response = master.send(&request)?;
assert!(response.is_success());

Trait Implementations

impl Debug for Master

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.