Skip to main content

Sniffing the Buderus Logamatic 4000 bus

Avid readers of this blog might know that I already had a couple of projects around the heating in our house. The latest addition to these projects is a mechanism to listen in on the Buderus's bus to gather and log information such as outside temperature, target temperatures in the heating circuits, turn-on and turn-off temperatures of the burner, etc.

My intention with this information is to improve heating efficiency (as measured in gas used) and also to get a more in-depth understanding of the engineering aspects of this system (mechanical & electronic engineering and computer science).

Previously I've installed DS18B20 sensors all around, monitoring the system from the "outside", by sniffing the bus, I get a peek into the inside of the system.

When I started, I've found the site https://www.holzleitner.com/el/buderus-monitor/index-en.html which contained a reverse-engineered description of how the bus system of Buderus works.

Then I've stumbled into the  BBQKees webshop which sells complete boards to connect a Raspberry Pi to the boiler, from which I quickly purchased one.

Unfortunately the BBQKees board turned out to be incompatible with my boiler, but I've learnt a lot from trying to make it work:

  • had to le-learn electronics basics, voltage dividers, capacitors, etc
  • the use of an oscilloscope, even outside of my lab (e.g. connected to the boiler and various points on the board)
  • the electrical encoding of an RS232 signal

I couldn't make the BBQKees board work, which is a but of a let-down but I truly enjoyed the process. The details have been documented on this twitter thread.

With that failure, I decided to solder my own board, as described on the Holzleitner site. And with that I was successful.

My RPi is now receiving the 1200 8N1 signal that the boiler is sending out to the room unit, which I can now use to chart changes in boiler behavior in Homeassistant.

 

The chart shows a combination of data acquired via DS18B20 sensors and the data acquired via the bus sniffer:

  • the red chart shows the temperature of the hot water produced by the boiler (DS18B20),
  • the green one is the internal temperature of the boiler (reported by the boiler)
  • the two straight lines show the turn-on and turn-off temperature of the burners (also from the bus)
  • And the history chart on the top shows wether the burner is active or not.

This is just the beginning. I intend to attach a sensor to our gas meter, so I can relate the burning time with the amount of gas used. But I also have plans to change how the system controls pumps, as I am pretty convinced that the way it works right is not ideal. I am going to monitor this data, in order to get a baseline and to confirm my hypothesis.

36550006300672?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E1354836550006300672%7Ctwgr%5E%7Ctwcon%5Es1_c10&ref_url=https%3A%2F%2Fpublish.twitter.com%2F%3Fquery%3Dhttps3A2F2Ftwitter.com2FBazsi7712Fstatus2F1354836550006300672widget%3DTwe

Comments

Jieffe said…
Great job ! I've grabbed the popcorn and am waiting for the next episode :)

I've got a Buderus boiler too and I'd like to retrieve data from it.

Popular posts from this blog

syslog-ng fun with performance

I like christmas for a number of reasons: in addition to the traditional "meet and have fun with your family", eat lots of delicious food and so on, I like it because this is the season of the year when I have some time to do whatever I feel like. This year I felt like doing some syslog-ng performance analysis. After reading Ulrich Deppert's series about stuff "What every programmer should know about memory" on LWN, I thought I'm more than prepared to improve syslog-ng performance. Before going any further, I'd recommend this reading to any programmer, it's a bit long but every second reading it is worth it. As you need to measure performance in order to improve it, I wrote a tool called "loggen". This program generates messages messages at a user-specifyable rate. Apart from the git repository you can get this tool from the latest syslog-ng snapshots. Loggen supports TCP, UDP and UNIX domain sockets, so really almost everything can be me...

syslog-ng contributions redefined

syslog-ng has been around for about 12 years now, but I think the biggest change in the project's life is imminent: with the upcoming release of syslog-ng OSE 3.2, syslog-ng will become an independent entity. Until now, syslog-ng was primarily maintained & developed by BalaBit, copyrights needed to be reassigned in order to grant BalaBit special privileges. BalaBit used her privileges to create a dual-licensed fork of syslog-ng, named "syslog-ng Premium Edition". The value we offer over the Open Source Edition of syslog-ng are things that larger enterprises require: support on a large number of UNIX platforms (27 as of 3.1), smaller and larger feature differences (like the encrypted/digitally signed logfile feature) better test coverage and release management longer term support Although perfectly legal, this business model was not welcome in various Free Software communities, and has caused friction and harm, because BalaBit has enjoyed a privilege that no others cou...

An introduction to db-parser()

As promised on the mailing list here comes a short description of the new db-parser functionality of syslog-ng. For an introduction to parsers in general see my previous blog post here . The aim for db-parser is two-fold: extract interesting information from a log message attach tags to a log message for later classification. For instance here's a log sample (lines broken for readability): Feb 24 11:55:22 bzorp sshd[4376]: Accepted password for bazsi \ from 10.50.0.247 port 42156 ssh2 This message states that a user named "bazsi" has logged into the host named "bzorp" using SSH2 from the quoted IP and port. When you read this message as a human, the event that happened is perfectly clear. However if it is not a human, but a piece of software that has to make out the meaning of the message, you need to identify the event (e.g. that a user login has happened) and the additional information associated with the event (e.g. that he used 10.50.0.247 as the cl...