A collection of FHEM-related drop-in plugins for Munin
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If you are running FHEM with a lot of devices and want to have Munin graphs for sensor readings, it quickly becomes cumbersome and repetitive to add new graphs. A FHEM system with a little history might also use inconsistent naming which makes things confusing. These plugins aim to automatically pick up changes in your FHEM infrastructure and display new devices automatically.

The plugins use the list command of FHEM to find devices with appropriate "readings" for each plugin. That way new devices are picked up automatically and the plugins don't need to care about device names.

I only own and test with HomeMatic devices but I guess these plugins may work for other hardware as well.


  • fhem_auto_battery Render voltage level for all FHEM devices with a batteryLevel reading. Warning level is set to 2.3V which should work for HomeMatic devices.
  • fhem_auto_battery_ok Render battery status for all FHEM devices with a battery reading. The states "ok", "low" are mapped to 0 or 1, all other to 2. Warning level is configured to be 1 so Munin reports low batteries correctly.
  • fhem_auto_battery_percentage Render battery status if it is given in FHEM as a number with %. Standard for warning and critical are 40 and 20 percent.
  • fhem_auto_brightness Render brightness level for all FHEM devices with a brightness reading.
  • fhem_auto_current Render (electrical) current for all FHEM devices with a current reading.
  • fhem_auto_dew Render calculated dew points for devices with both a temperature and a humidity reading.
  • fhem_auto_energyCalc Render power usage for devices with an energyCalc reading. This is a DERIVE graph and can be used as an alternative to fhem_auto_power. While the latter only shows measurements fron a specific points in time, this plugin better shows peak values because the energyCalc reading includes the cumulative change between measurements.
  • fhem_auto_humidity Render relative humidity for devices with a humidity reading.
  • fhem_auto_humidity_abs Render calculated absolute humidity for devices with both a temperature and a humidity reading.
  • fhem_auto_frequency Render frequency for devices with a frequency reading.
  • fhem_auto_motion Render derived motion events for motion detectors (subType=motionDetector).
  • fhem_auto_power Render power usage of devices with a power reading.
  • fhem_auto_resident_state Renders the state of the residents (ROOMMATE and GUEST).
  • fhem_auto_switch Render status of switches (attribute state either on or off and not a dummy).
  • fhem_auto_temp Render temperature readings of (root) devices with either a temperature or measured-temp reading and, in the latter case, as long as their channel_02 is not peered to a different device. This avoids reporting duplicate values for HomeMatic thermostat valves that use an external temperature sensor (and possibly others).
  • fhem_auto_temp_desired Render target temperatures of devices with either a desired-temp or a setpointTemp reading.
  • fhem_auto_valve Render valve opening positions of devices with a ValvePosition reading.
  • fhem_auto_voltage Render voltage of devices with a voltage reading.
  • fhem_auto_status Render FHEM device status (alive/dead/unknown/off) for ActionDetector devices.
  • fhem_auto_reading_ Wildcard plugin to render arbitrary readings without fancy device filtering or configuration. Please note that the values returned for the readings need to be numeric (integer/decimal).

I also started to add multigraph variants for existing plugins, the first one being fhem_auto_valve_multi. Grouping is currently done by room.


Just drop the plugins into /etc/munin/plugins and restart munin-node. If your FHEM installation's telnet service is accessible on localhost:7072 everything should work automatically. Otherwise you need to set fhem_host and fhem_port in your plugins.conf:

env.fhem_host fhem.example.org
env.fhem_port 8888

None of the plugins need any special privileges. There is no need to run them as root.

The only external dependency is netcat which is used to communicate with FHEM. The netcat binary is called as nc and is expected to be in $PATH.

If you want more fancy labels or if you want to create graphs with data from several of the pre-defined graphs, you can borrow data like so in munin.conf:

    use_node_name no
    update no
    temp_wohnzimmer.update no
    temp_wohnzimmer.graph_title Temperaturen Wohnzimmer
    temp_wohnzimmer.graph_args --base 1000
    temp_wohnzimmer.graph_vlabel degrees Celsius
    temp_wohnzimmer.graph_scale no
    temp_wohnzimmer.graph_category fhem
    temp_wohnzimmer.graph_printf %6.1lf
    temp_wohnzimmer.graph_order \
        Wohnzimmer=jigsaw.home.well-adjusted.de:fhem_auto_temp.WandTherm_Wohnzimmer \
        TargetWohnzimmer=jigsaw.home.well-adjusted.de:fhem_auto_temp_desired.WandTherm_Wohnzimmer \
        DewWohnzimmer=jigsaw.home.well-adjusted.de:fhem_auto_dew.Dew_WandTherm_Wohnzimmer_Weather \
    temp_wohnzimmer.Wohnzimmer.label Ist-Temperatur Wohnzimmer OG
    temp_wohnzimmer.TargetWohnzimmer.label Ziel-Temperatur Wohnzimmer
    temp_wohnzimmer.DewWohnzimmer.label Taupunkt Wohnzimmer
    temp_wohnzimmer.DewAmbient.label Taupunkt aussen


Here's my setup with all default graphs: http://jigsaw.home.well-adjusted.de/munin/fhem_auto-week.html

And a few custom graphs that only aggregate data from the default graphs: http://jigsaw.home.well-adjusted.de/munin/home.well-adjusted.de/FHEM/index.html


  • Make hostname and port of FHEM configurable. Currently localhost:7072 is hard-coded everywere.
  • Add a wildcard plugin where you only have to give the name of a reading.
  • Make netcat path configurable.
  • Add more multigraph variants
  • Refactor common code (patterns) into external file.


For questions and support, feel free to use the Issue Tracker or drop me an e-mail at js+github at wim.re.