Z21Station

A Rust library for asynchronous communication with a Roco Fleischmann Z21 digital command control (DCC) station for model railways.

Overview

This crate provides a complete UDP-based API for interacting with the Z21 station, handling command transmission and event reception through an asynchronous architecture powered by the Tokio runtime.

Features

• Automatic connection management with keep-alive functionality
• Broadcast message handling for system state changes
• Locomotive control (speed, direction, functions)
• Support for different DCC throttle steps (14, 28, 128)
• Track power control
• Asynchronous, subscription-based event handling
• Error handling
• Ready to use driver for integration into other projects

Installation

Add this to your Cargo.toml:

[dependencies]
z21_driver = "0.1.0"
tokio = { version = "1", features = ["full"] }

Usage Examples

Basic Connection

use roco_z21_driver::Z21Station;
use std::sync::Arc;
#[tokio::main]
async fn main() -> std::io::Result<()> {
    // Create a connection to the Z21 station
    let station = Arc::new(Z21Station::new("192.168.0.111:21105").await?);

    // Get the serial number of the station
    let serial = station.get_serial_number().await?;
    println!("Z21 station serial number: {}", serial);

    // Turn on track power
    station.voltage_on().await?;

    // Subscribe to system state updates
    station.subscribe_system_state(
        1.0,
        Box::new(|state| {
            println!("Main track voltage: {:.2}V", state.vcc_voltage);
            println!("Temperature: {}°C", state.temperature);
            println!("Current: {}mA", state.main_current);
        }),
    );

    // Keep the application running
    tokio::signal::ctrl_c().await?;

    // Turn off track power before exiting
    station.voltage_off().await?;
    station.logout().await?;

    Ok(())

    //Ok(())
}

Controlling a Locomotive

use roco_z21_driver::{Loco, Z21Station};
use std::sync::Arc;
use tokio;

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let station = Arc::new(Z21Station::new("192.168.0.111:21105").await?);

    // Control a locomotive with address 3
    let loco = Loco::control(station.clone(), 4).await?;

    // Subscribe to locomotive state changes
    loco.subscribe_loco_state(Box::new(|state| {
        println!(
            "Locomotive speed: {}%",
            state.speed_percentage.unwrap_or(0.)
        );
    }));

    // Turn on the headlights
    loco.set_headlights(true).await?;

    // Set speed to 50% forward
    loco.drive(50.0).await?;

    // Wait for 5 seconds
    tokio::time::sleep(tokio::time::Duration::from_secs(5)).await;

    // Gradually stop
    loco.stop().await?;

    Ok(())
}

API Documentation

Z21Station

The Z21Station struct provides methods to interact with the Z21 station:

• new(bind_addr: &str) -> io::Result<Self>: Creates a new connection to a Z21 station
• voltage_off() -> io::Result<()>: Turns off the track voltage (emergency stop)
• voltage_on() -> io::Result<()>: Turns on the track voltage
• get_serial_number() -> io::Result<u32>: Retrieves the serial number from the Z21 station
• subscribe_system_state(freq_in_sec: f64, subscriber: Box<dyn Fn(SystemState) + Send + Sync>): Subscribes to system state updates
• logout() -> io::Result<()>: Logs out from the Z21 station

Locomotive Control

The Loco struct provides methods to control DCC locomotives:

• control(station: Arc<Z21Station>, address: u16) -> io::Result<Loco>: Controls a locomotive with default throttle steps (128)
• control_with_steps(station: Arc<Z21Station>, address: u16, steps: DccThrottleSteps) -> io::Result<Loco>: Controls with specific throttle steps
• drive(speed_percent: f64) -> io::Result<()>: Sets the speed of the locomotive (-100.0 to 100.0)
• stop() -> io::Result<()>: Performs a normal locomotive stop
• halt() -> io::Result<()>: Stops the train immediately (emergency stop)
• set_function(function_index: u8, action: u8) -> io::Result<()>: Controls a locomotive function (F0-F31)
• function_on(function_index: u8) -> io::Result<()>: Turns on a specific locomotive function
• function_off(function_index: u8) -> io::Result<()>: Turns off a specific locomotive function
• function_toggle(function_index: u8) -> io::Result<()>: Toggles a specific locomotive function
• set_headlights(on: bool) -> io::Result<()>: Convenience method to control the locomotive's headlights (F0)
• subscribe_loco_state(subscriber: Box<dyn Fn(LocoState) + Send + Sync>): Subscribes to locomotive state changes

License

This project is licensed under either of:

-BSD 3-Clause License, see LICENSE-BSD file

at your option.

Contributions

Contributions are welcome! Please feel free to submit a Pull Request.