These instructions are for the Dymo M25 postal scale on Windows 8, Windows 10, or Mac OS X but with a little hacking other scales and operating systems should be usable.

readscale.cgi is a modified version of the code found here (used with permission): http://steventsnyder.com/reading-a-dymo-usb-scale-using-python/

The newest version serves the scale values via Websockets

Vendor and products ids for the m25 should be 0922 and 8004 respectively. If your scale is different, update readscale.py with its values. you'll also need to know them for the install procedure below.

On the computer that needs to read from the scale:

• Install python 2.7

• Update your path information so that you can use pip and python in the shell

  • Right Click on the Start icon
  • Select System
  • Select Advanced system settings
  • Click on Environment Vriables...
  • Select Path from the System variables list
  • Click Edit...
  • Verify or add entries for C:\Python27\ and C:\Python27\scripts\
  • Click OK to exit from the menus
  • If you are still having issues running pip you can also replace the pip commands below with

  python -m pip install ...

• Install gevent and gevent-websocket pip install gevent gevent-websocket

For Windows installations:

• Install pyusb pip install pyusb
• Install the proper driver so that Python can talk to the scale on Windows. There are many ways to do this, but the recommeded method is with Zadig
  • Plug in the scale and turn it on
  • Open Zadig
  • Click Options > List All Devices
  • Select M25 25 lb Digital Postal Scale
  • We've had the best luck with the libusbK driver, but you may have to play around a little
  • Click Install Driver
  • You should disconnect and reconnect the scale at this point

For Mac OSX installations:

• Install hidapi pip install hidapi

If you need to serve the scale values over HTTPS (which you probably should). You will need a certificate and private key.

Here is an example of creating keys and certs using OpenSSL

openssl req -newkey rsa:2048 -nodes -keyout key.pem -x509 -days 365 -out certificate.pem

We should now be ready to test that the scale server is working correctly

Now to serve up that value:

• Start the server

python scaleServer.py -k <keyfile> -c <certfile>

• Open a browser and go to https://localhost:8000/
• Validate the the scale values will live update in the form provided! Clicking record will lock in the values and close the websocket

To use the server in your own web app, just make the appropriate changes to the code found within the <script> tags in templates/index.html

If you'd like to run the server in the background, you might consider using pythonw