# Free Online Serial Port Monitor — G F Electronics

Browser-based serial terminal for testing weighing scales, indicators, receipt printers and any RS-232 / USB serial device. Free, no download, no signup.

HTML version / live tool: /pages/serial-port-monitor.html

## Features

- **Connection settings:** selectable baud rate (300–921600 plus custom), data bits (7/8), parity (none/even/odd), stop bits (1/2), RTS/CTS flow control
- **Terminal views:** ASCII, HEX, or combined HEX+ASCII; optional timestamps; autoscroll; pause; clear
- **Transmit:** send text or HEX with selectable line ending (CR / LF / CR+LF / none)
- **Session logging:** save the full session log to a file
- **Auto baud-rate detection:** finds the rate that produces clean data automatically
- **Scale mode:** live weight display with stability (HOLD) detection, parse-factor selection (auto, ×1, ÷10, ÷100, ÷1000, or calibrated) and a "scale display shows" calibration input to compute the exact factor
- **Demo mode:** try the terminal with simulated scale data, no device needed

## Requirements

- Works in **Google Chrome, Microsoft Edge or Opera on desktop** (Web Serial API). Not supported in Firefox, Safari or mobile browsers.
- For RS-232 scales, use a USB-to-RS232 converter (CH340, CP2102, FTDI or PL2303 chip — install the driver if no COM port appears).
- Most scales transmit at 9600 baud, 8 data bits, no parity, 1 stop bit.

## Common uses

1. Verify a weighing scale is transmitting serial data before software integration
2. Find an unknown baud rate with auto-detect
3. Diagnose garbage characters (wrong baud/parity settings)
4. Read live weight with stability detection before connecting to billing/POS/ERP software

Need help or a complete weighing solution? Contact G F Electronics: +91 99583 05151 (call/WhatsApp) · kuljit@gfelectronic.com · /pages/contact.md