Quick start

SeaHi Serial is a serial and Bluetooth debugging tool for Windows. This page covers installation, connecting your first serial port, and sending a command.

Requirements

Windows 10 or 11. WebView2 is usually included with the system; the installer will prompt if it is missing. USB-serial adapters need their driver installed, and the COM port should appear in Device Manager.

Install

1. Open Releases and download the .msi or Seahi-Serial-Setup-*.exe.
2. The installer is unsigned, so SmartScreen will warn you. Click More info, then Run anyway.
3. Launch the app from the Start menu after installation.

The release page also includes SHA256SUMS.txt and a cosign .sigstore.json bundle. See Code signing and installation for verification steps.

Connect your first port

1. Plug in the device.
2. Pick the COM port in the toolbar. The list refreshes when devices are plugged or unplugged.
3. The baud rate defaults to 115200. Choose another common value or type a custom one.
4. Click Start monitoring. The button changes to Stop monitoring, and data starts appearing in the output area.

Data bits, stop bits, parity, and DTR/RTS are in the gear menu.

Sending a command on COM9; the device response appears in the output area.

Send a command

Type in the input box and press Enter, or click Send. Text mode sends UTF-8; switch to HEX mode to send raw bytes.

Choose the line ending in the toolbar: \r, \n, or \r\n. AT commands commonly use \r\n; check the module documentation.

Each pane keeps the last 50 sent lines. Use ↑ and ↓ to browse them.

If the device does not respond, check the baud rate and line ending, and make sure no other program is using the COM port. A serial port can only be opened by one program at a time.

Logs

While a serial port is open, the app caches the session to disk, keeping the last 10 sessions:

%APPDATA%\seahi-serial\log-cache\session-<timestamp>-<port>.log

Use Save log to keep a permanent copy.

Next

• Serial debugging: panes, line endings, DTR/RTS, logs, and workflows
• Terminal mode: turn the output area into a terminal
• Quick commands: send commands in repeating groups
• MCP setup: connect an AI client
• Bluetooth
• ADB and WSL