A serial/TCP/UDP monitor and protocol gateway — alternative to Hercules.

Runs in two modes:

• GUI — desktop app (Tauri + Svelte 5) for interactive monitoring
• API — REST + WebSocket gateway (Axum) for scripting and automation, with embedded web UI

Features

• Serial connections — RS-232 and RS-485; configurable baud rate, data bits, parity, stop bits, flow control; DTR/RTS control
• TCP connections — client mode and server (listener) mode
• UDP connections — bind to a local port, send/receive datagrams
• Multi-tab UI — open multiple connections simultaneously, each in its own tab
• Timestamped frame log — every RX/TX frame is logged with direction and timestamp
• WebSocket live stream — subscribe to /api/connections/{id}/stream for raw bytes and decoded frames in real time
• REST API — open/close connections, send raw data, list serial ports, set DTR/RTS

Modbus

• Protocols: Modbus RTU, ASCII, and TCP
• Request builder: function codes FC01 (Read Coils), FC02 (Read Discrete Inputs), FC03 (Read Holding Registers), FC04 (Read Input Registers), FC05 (Write Single Coil), FC06 (Write Single Register), FC15 (Write Multiple Coils), FC16 (Write Multiple Registers)
• Response decoder: automatic parsing and display of register/coil data
• Display formats: hexadecimal, uint16, int16, uint32, int32, float32, string
• Byte swap and word swap options for multi-register values
• Configurable timeout and retry settings, saved per session

Prerequisites

• Rust (stable)
• Node.js ≥ 18
• Tauri CLI: cargo install tauri-cli --version "^2"
• On Windows: WebView2 (pre-installed on Windows 10/11)

Setup

git clone https://github.com/deid84/conduit
cd conduit/frontend
npm install
cd ..

Running

GUI (Tauri desktop app)

cd crates/conduit-tauri
cargo tauri dev

Tauri starts the Vite dev server automatically and opens the app window.

API gateway (Axum REST + WebSocket + UI)

Build the frontend first, then start the server:

cd frontend && npm run build && cd ..
cargo run --bin conduit-api
# Listening on 0.0.0.0:3000
# Open http://localhost:3000 in a browser

The binary serves frontend/dist as static files with an index.html fallback for client-side routing. To override the path:

# via environment variable
CONDUIT_STATIC_DIR=/path/to/dist cargo run --bin conduit-api

# or via .env file in the working directory
echo 'CONDUIT_STATIC_DIR=/path/to/dist' > .env
cargo run --bin conduit-api

Frontend only (Vite dev server)

cd frontend
npm run dev
# http://localhost:8419

Building for production

# GUI — produces a native installer
cd crates/conduit-tauri
cargo tauri build

# API gateway — optimized binary
cargo build --bin conduit-api --release

Workspace structure

conduit/
├── crates/
│   ├── conduit-core/   # transport logic: serial, TCP, UDP
│   ├── conduit-api/    # Axum REST + WebSocket gateway (binary: conduit-api)
│   └── conduit-tauri/  # Tauri desktop app (binary: conduit)
└── frontend/           # Svelte 5 + Vite

License

Licensed under either of MIT or Apache 2.0 at your option.