I have removed the MySQL database.  I did get pysftp installed (which was much more challenging than expected).  I also did load and modify the code to access the sensor.  Other than that, I have spent a lot of time reading up on SFTP and may have come up with the best scheme yet to get snow measurement data into the weather database.

From the pysftp documentation and the documentation for the version of Linux I’m running, I may be able to execute commands on the snow measurement machine remotely from the weather station machine and read back the results of those commands.  If this works it means that the snow measurement machine would have the relatively simple task of accessing the ultrasonic sensor and the weather station machine would have the relatively simple task of periodically asking the measurement system for a new reading. No more cron job, no more messy file transfer, no more worry about asynchronous file read/write collisions.  This all hinges on the ability to execute commands remotely which I have yet to test.

Other than that, a couple parts came in today.  The ultrasonic senor and a real time clock module arrived.  I plan to install the real time clock tomorrow.

One little obstacle has arisen… the cable that I need to run from the snow measurement machine out to the sensor is a little pricey at about $50 for 100 feet.  I’m holding of on spending that till I get everything working in the house on short cable runs.

Most critical next steps are:

1. Install and set up the real time clock.
2. Test pysftp and see if it really is capable of remote command execution.
3. Make sure that I can remotely execute a python program and read back the results remotely.