PortDock

Web Serial Terminal

Open a COM port from a browser that supports Web Serial (Chrome, Edge and others) and talk to a device. HEX/ASCII view, timestamps, checksum and line endings.

Not connected

Outgoing bytes are built as «body + checksum + line ending» (the checksum covers the body only). Data only travels between this browser and the port; nothing is uploaded.

How to use

  1. Match baud rate, data bits, parity, stop bits and flow control to the device manual (usually 9600 or 115200, 8N1, no flow control).
  2. «Choose port & connect» opens the browser's port picker. A web page can only open a port that you pick.
  3. Received bytes are grouped into lines «at each LF» or «after 20 ms idle». LF suits text devices; idle suits frame-based devices such as Modbus RTU.
  4. Enter HEX as «01 03 00 00 00 0A» and ASCII as «AT\r\n» or «\x02DATA\x03» (same rules as the CRC & checksum calculator).

Supported browsers

Per the MDN compatibility data (api.Serial): Chrome and Edge 89+, Firefox 151+ (desktop), Chrome for Android 148+ (138–147 only Bluetooth RFCOMM serial ports). Safari, iOS, Firefox for Android and Android WebView are not supported. The specification limits it to secure (https) pages, and a port opens only after you pick it.

FAQ

My COM port is not in the list

Check that the port shows up in Device Manager and that the USB-serial adapter driver is installed. If another program has the port open, connecting fails.

I see garbage characters

If baud rate, data bits, parity or stop bits differ from the device in any way, you get corrupted bytes. Fix the settings and reconnect. Framing and parity errors are noted in the log.

What happens when I unplug the USB cable?

When reading fails or the port fires its disconnect event, the log shows «disconnected» and the port is closed. Plug it back in and press «Choose port & connect».

To watch several ports at once, verify received checksums, decode Modbus RTU or reconnect USB automatically, use PortDock Serial.

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