How do I check if my weighing scale is sending serial data?

Connect the scale to your PC with its RS-232 or USB cable, open this page in Chrome or Edge, click Connect, choose the COM port and set the baud rate (most scales use 9600). Put some weight on the scale — if it is transmitting, the readings appear immediately in the terminal. If you are unsure of the baud rate, use the Auto-detect baud button.

Why does my serial device show garbage characters?

Garbage characters almost always mean the baud rate, data bits or parity do not match the device settings. Try the Auto-detect baud feature, or check the device manual for its serial output settings (commonly 9600 baud, 8 data bits, no parity, 1 stop bit).

Do I need to install any software or driver?

No software installation is needed — this tool runs entirely in Google Chrome or Microsoft Edge. If Windows does not show a COM port for your USB-serial cable, you may need the driver for its chip (usually CH340, CP2102, FTDI or PL2303).

Free tool from G F Electronics

Free Online Serial Port Monitor

Test weighing scales, indicators, receipt printers and any RS-232 / USB serial device directly in your browser. Selectable baud rate, HEX view, auto-baud detection and a live weight display — no download, no signup.

Connection

Baud rate

Data bits

Parity

Stop bits

Flow control

Checking browser…

HEX

Scale mode — live weight display with stability detection

How to connect your weighing scale to a PC

Most weighing scales and indicators have a serial output — either a 9-pin RS-232 (DB9) connector or a USB port. To read the data on a computer:

Connect the cable. For RS-232 scales use a USB-to-RS232 converter cable; for USB scales connect directly. Windows will create a COM port (check Device Manager → Ports).
Install the driver if needed. Most converter cables use a CH340, CP2102, FTDI or PL2303 chip. If no COM port appears, install that chip's driver.
Click Connect above and select the COM port. Most scales transmit at 9600 baud, 8 data bits, no parity, 1 stop bit — the default settings here.
Put weight on the scale. Many scales only transmit when weight changes or when stable. If you see nothing, check the scale's serial output mode in its settings.

Seeing garbage characters?

Wrong baud rate is the usual cause — click Auto-detect baud and the tool will find the rate that produces clean data. If data still looks wrong, try 7 data bits with Even parity, which some older indicators use.

What is Scale mode?

Scale mode parses the numeric weight out of the incoming data and shows it on a large live display with stability (HOLD) detection — the same logic we use in our POS and weighbridge software. It's an easy way to verify a scale's output before integrating it with billing or ERP software.

Need help, or a complete weighing solution?

G F Electronics manufactures tabletop scales, bench scales, chicken scales and weighbridges — and builds the software that connects them to billing, POS and ERP systems. If your device shows no data or garbage output, we can help.