System4Dispatch

A dispatch panel and throttle for model railroads running OpenLCB / LCC. It runs in the browser or as a desktop app.

• Draws your CTC-style track diagram and shows live block occupancy.
• Throws turnouts with a tap, and shows feedback from the points when you have it.
• Throttles: acquire any DCC address through an LCC command station (Traction protocol). You get speed, direction, F0–F28 and emergency stop.
• Layout editor: paint track, assign blocks and turnouts, and enter event IDs. Every block gets its own colour and name tag. You can select many tiles at once (drag a box or shift-click) and link turnouts such as crossover ends so they always throw together. You can also learn an event ID by pressing a button on the layout.
• A built-in simulator, so you can try everything without hardware.
• Written in Rust with Dioxus: the same app compiles to WebAssembly for the browser and to a native desktop app. The OpenLCB stack is rolcb.

Documentation: https://www.uncommonmodels.com/System4Dispatch/docs/ (sources in docs/, built with mdBook)

Ways to connect

All connections speak GridConnect, the text form of LCC's CAN frames.

Connection	Web app	Desktop app
USB adapter (RR-CirKits LCC Buffer-USB, TCS, SPROG CANISB…)	✓ via Web Serial (Chrome or Edge on a desktop computer)	✓ pick the port in Settings
GridConnect TCP: JMRI's LCC hub, an Ethernet LCC buffer, rolcb-hub (port 12021)	— (browsers can't open TCP sockets)	✓
Simulator	✓ (default)	✓

• Web app: https://www.uncommonmodels.com/System4Dispatch/. You can also install it as a PWA so it works offline.

• Desktop app: download from the releases page:

  Platform	Download
  Linux x86_64	.deb, .rpm, .AppImage or .flatpak
  Linux arm64 (Raspberry Pi 4/5, 64-bit OS)	.deb or .rpm
  macOS	.dmg (Apple silicon or Intel)
  Windows	.msi or -setup.exe
  Self-hosted web app	-web.zip

  Per-platform instructions are in the Installing chapter of the docs. Daily testing builds (5am US Eastern) are on the nightly pre-release.

Each running copy is its own OpenLCB node with a unique Node ID, generated on first run and editable in Settings. Several dispatchers and throttles can run at once.

A serial port can only be opened by one program. To share one USB adapter between JMRI and several panels, run rolcb-hub and connect everything to it over TCP:

rolcb-hub --serial /dev/ttyACM0          # GridConnect TCP on :12021

Layout files

A layout is a JSON file: a grid of track tiles, plus the blocks and turnouts they belong to and the events that drive them. See crates/core/demo-layout.json.

{
  "version": 1,
  "name": "Hilltown Subdivision",
  "grid": { "cols": 32, "rows": 12 },
  "blocks": [
    { "id": "B1", "name": "West Main",
      "occupied_event": "05.01.01.01.22.00.00.10", "clear_event": "05.01.01.01.22.00.00.11" }
  ],
  "turnouts": [
    { "id": "T1", "name": "Hilltown West",
      "normal_event": "05.01.01.01.22.00.01.00", "reverse_event": "05.01.01.01.22.00.01.01",
      "feedback": { "normal_event": "05.01.01.01.22.00.02.00", "reverse_event": "05.01.01.01.22.00.02.01" },
      "linked": "T2" }
  ],
  "elements": [
    { "type": "track", "x": 2, "y": 6, "shape": "straight", "rot": 0, "block": "B1" },
    { "type": "track", "x": 6, "y": 6, "shape": "turnout_left", "rot": 0, "block": "B2", "turnout": "T1" },
    { "type": "label", "x": 12, "y": 3, "text": "Hilltown" }
  ]
}

• Shapes: straight, curve, bumper, crossing, crossing_diag, turnout_left, turnout_right, wye. rot turns the tile clockwise in 45° steps (0–7).
• Blocks: the panel sends Identify Producer for each event at startup, so it learns the current state straight away. Producer Identified Valid/Invalid and PCERs keep it up to date.
• Turnouts: tapping sends the throw event as a PCER. With feedback events, the turnout blinks until the points report back. Without feedback, it shows the last command seen on the bus. linked names a second turnout that is always thrown with this one (both sides name each other); "linked_inverted": true sends it to the opposite position.

Layouts are saved in the browser (web) or your config folder (desktop), and can be exported and imported as files.

Building

You need Rust, the wasm32-unknown-unknown target and the Dioxus CLI. rolcb must be checked out next to this repo (../rolcb).

rustup target add wasm32-unknown-unknown
cargo install dioxus-cli --version 0.7.10 --locked

cargo test                                                    # core logic tests
dx serve -p system4dispatch                                   # web app at http://localhost:8080
dx serve -p system4dispatch --platform desktop                # desktop app
dx bundle -p system4dispatch --platform web --release         # static site
dx bundle -p system4dispatch --platform desktop --release     # installers

On Linux the desktop build needs WebKitGTK and friends. On Fedora: sudo dnf install webkit2gtk4.1-devel gtk3-devel libxdo-devel libsoup3-devel systemd-devel. On Debian/Ubuntu: sudo apt install libwebkit2gtk-4.1-dev libgtk-3-dev libxdo-dev libudev-dev.

Repository layout:

crates/core   layout model, Dispatcher (OpenLCB state machine), Simulator; host-testable
crates/app    the Dioxus app; src/platform/{web,desktop}.rs hold the per-platform links and storage

GitHub Actions run the tests, publish the web app and the docs to GitHub Pages, attach installers for every platform (plus a Flatpak and a self-hostable web app) to tagged releases, and publish a nightly testing pre-release (tag nightly) for every platform at 5am US Eastern. Build the Flatpak locally with the commands at the top of packaging/flatpak/com.uncommonmodels.System4Dispatch.yml.

License

MIT