Bash and Python to make it happen

Before anything else, I should give credits to Marco Bakker for sharing his scripts that got me started straight away. Within one day after I got my Raspberry Pi, I had it capture P1 telegrams, generate graphs and even upload data to external logging sites. In the weeks that followed I polished the script alot, and the result of that is what this post is about.

An overview of the most important changes:

• Calculations are now based on the actual time between measurements. Even though the script is triggered every 5 minutes, the exact time between measurements can vary because of the fact that we may have to wait up to 10 seconds for the telegram to arrive. But it's also possible that the Raspberry Pi has had some downtime and resumes after an unknown period of time.
• The script was getting so big that it was hard to navigate around, so I split it into smaller parts; one that holds all the configuration, one that contains the long rrdtool commands, another one that outputs data into various file formats, and a last one that contains interfaces to external websites.
• Clean output, so we can capture it to a useful log.
• Various readability, robustness and flow tweaks.

Also a little disclaimer; the original script provides support for several features that I don't use myself, and are therefore untested (but perhaps fully functional) in my version of the script:

• Upload to Xively.
• P1 dsmr v4 format. In principle, you could easily support any P1 format by adding an appropriate awk script.
• Output to csv format.
• Output to html page. The generated html is awfully retro, but I haven't bothered changing it.

This script is distributed under the GNU General Public License v3, and by downloading the script you agree to the terms of this license. Furthermore, usage is at your own risk and without guarantees. mbsolget_svg  .tar.gz (10kb) .zip (12kb)

Optional dependencies: rrdtool, ncftp, sendemail, mysql

After extraction into its own directory, the only thing you need to do is edit config.sh to set P1PORT to the name of the serial device that connects to the P1 port, and also set the correct WORKDIR (and actually anything else you find in there - but let's keep it simple for now).

Finally, make the main script executable with: chmod +x mbsolget_p1.sh

You're ready to go, so give it a test run: ./mbsolget_p1.sh

No errors? Good, then you'll find a bunch of new files and directories. Note that most interesting stuff is configured to happen on every 5 minute interval of the hour.

The raw captured P1 telegrams are stored as log/p1-YYYYMMDD-hhmm.log
The extracted values of the last P1 telegram are stored in p1_gas.tmp and p1_value.tmp
All calculated statistics are written to debug.tmp, the meaning of which are in comments inside the main script. These statistics are used to build the json, csv, sql or xml data output.
In order to initialize your rrd storage file, you should run the script once with the 'create' argument: ./mbsolget_p1.sh create

When you have it configured the way you want, schedule the script to run automatically with crontab -e, and add the following line (but with the proper path of course):
*/5 * * * * /home/pi/path/to/mbsolget_p1.sh >> ~/log/mbsolget.log 2>&1

At this point - and for me this was early april - the data flow shown in last post is fully functional (except for the backup part, but this is just another cron job). I'll leave it to you to get creative with the json or xml that is pushed to your webserver every 5 minutes. You could even write a smartphone app around it.

On the right I've included a screenshot of the dashboard I created. It keeps itself up-to-date by requesting the json and graphs periodically via ajax requests.

Next chapter: solar PV panels!