Weigh Station (scale-serial-reader)

An Electron desktop app that reads weights from a USB/serial shipping scale and injects them live into the OMS Weigh Station page.

The app opens https://oms.fulfillment.app/ in a window, finds the scale on a serial port, and, whenever the user is on a tools/weighStation page, writes the current reading into that page's form fields.

How it works

1. Startup: checks GitHub Releases for an update, then opens the OMS in a 1366×768 window.

2. Scale detection: once the page loads, it lists serial ports and picks the first one whose manufacturer is in manufacturerList (currently Prolific and FTDI). It connects at 9600 baud and reads line by line.

3. Parsing: each line is matched against:

   /(ST|US),(?:GS|GW),\s*([0-9.]+)\s*(lb|kg|kb)/
   

   For example, ST,GW, 0.00 lb gives weight 0.00 and units lb.

4. Stability: the app works out stability itself and doesn't trust the scale's ST/US flag. A non-zero weight that stays unchanged for stableTimer ms (default 1000) is marked ST (stable). Any change resets it to US (unstable).

5. Injection: on a tools/weighStation URL, the app sets these elements on the page:

   Element id	Set to
   weight (input)	current weight, e.g. 12.40
   status	ST or US
   units	lb / kg

Safety behavior

• The window closes with a notification if the PC loses internet (checked every second) or the scale disconnects.
• If no scale is found at launch, the app logs an error and stays open. It does not retry.

Requirements

• Node.js and npm
• Windows (the primary target; builds an NSIS installer). macOS has helper scripts but isn't actively maintained.
• A scale with a Prolific or FTDI USB-serial adapter that outputs the format above. For other adapters, add the manufacturer to manufacturerList in main.js.

Development

git clone https://github.com/Twistedst/scale-serial-reader.git
cd scale-serial-reader
npm install        # also rebuilds serialport for Electron (postinstall)
npm start          # runs against production OMS

To point at a local OMS on http://localhost:3000 with DevTools open:

npm run test-win   # Windows (NODE_ENV=WINDEV)
npm run test-mac   # macOS   (NODE_ENV=DEV)

WeighStation.bat is a shortcut that runs npm run start.

Environment variables

Variable	Purpose
NODE_ENV	DEV / WINDEV load localhost:3000 with DevTools; anything else loads production
stableTimer	ms a reading must hold steady before it's marked stable (default 1000)
GH_TOKEN	GitHub token with repo scope, needed only for npm run publish

Logs

Logs are written by electron-log. On Windows they go to: %USERPROFILE%\AppData\Roaming\ScaleSerialReader\logs\main.log

Building & releasing

npm run pack       # unpacked build in dist/win-unpacked (quick test)
npm run dist       # installer: dist/Weigh Station Setup <version>.exe

To release an auto-update:

1. Bump version in package.json.
2. Set GH_TOKEN (PowerShell: [Environment]::SetEnvironmentVariable("GH_TOKEN","<token>","User"), then restart the terminal).
3. Run npm run publish. This builds and uploads a draft release to GitHub.
4. Publish the draft on the GitHub Releases page.

Installed copies check for updates on launch and prompt the user to download and install.

Project structure

main.js          Main process: window, serial port, parsing, auto-update
renderer.js      Unused (legacy test renderer; the real UI is the OMS page)
WeighStation.bat Launch helper
assets/icons/    App icons
dist/            Build output (git-ignored)

Credits

Originally based on electron-serialport and the electron-updater example.

License

MIT. See LICENSE.