POS / Cash Detector

Native .NET Windows app for telling apart card/POS payments from normal cash.

It supports:

• POS reader sends text like a keyboard: scan/tap while the app is focused, then Enter if the reader does not do it automatically.
• POS reader sends serial data over a COM port: enter the port, for example COM3, then Start Serial.
• Cash payment: press F9 or click Cash.
• Every detection is saved to payments.csv.

Run

dotnet run

Publish an EXE

dotnet publish -c Release -r win-arm64 --self-contained false

The app will be under bin\Release\net8.0-windows\win-arm64\publish.

If your PC has x64 .NET instead of ARM64 .NET, use:

dotnet publish -c Release -r win-x64 --self-contained false

GitHub Releases

The release workflow builds three Windows executables:

• POS-Detector-win-x86.exe
• POS-Detector-win-x64.exe
• POS-Detector-win-arm64.exe

Create and push a version tag to publish a GitHub release:

git tag v1.0.0
git push origin v1.0.0

Configure

The first run creates detector_config.json.

{
  "PosKeywords": ["APPROVED", "AUTH", "PAID", "CARD", "POS", "TRANSACTION"],
  "MinimumSignalLength": 3,
  "DefaultBaudRate": 9600,
  "LogFile": "payments.csv"
}

If your reader sends a specific word or code, add it to PosKeywords.

How it decides

• If the POS reader fires any valid signal, the app records POS.
• If no POS signal fires and you press cash, the app records CASH.
• Very short signals are marked UNKNOWN, so random noise does not become a payment.

If your reader works through an API, webhook, printer cable, or a cash register protocol instead of keyboard/COM, this can be adapted once you know the model and connection type.