Fan control and feedback

  • Hardware Contributor

    Hi there.

    I'm currently trying to add fan control and monitoring to one of my projects. I'm using a CPU PWM fan with 4 wires.
    I can control the speed of the fan and read the rotation speed.

    Currently the fan is registered as a S_DIMMER where it sends its speed back to the controller (domoticz) as a V_VAR1. The nice thing being that if later on I decide to add an additional fan I can use V_VAR2, etc... Unfortunately domoticz seems to ignore V_VAR messages, I can't find a way to graph them or set units.

    As a workaround I don't see any sensor type that could be used to send RPMs either.

    It's unclear to me if I should ask for another sensor type in MyS such as a RPM/frequency/speed one or if it would be better to keep V_VAR and ask for a way to graph them in the controller.

    Is there an official position on this kind of issue, being compatible with all controllers?

  • Hero Member

    @emc2 As the V_VAR types have no specific meaning Domoticz cannot handle them in a structured way.
    For a fan I would choose a PERCENTAGE type and let Domoticz treat it as (the new) Selector switch. You can even choose a fan icon for it.
    V_VAR should be used for (temporary) storage of variables only.

  • Hardware Contributor

    Thanks for the heads up. The selector is an option, but the sliding ruler of the domoticz interface is actually more suitable in my current use. I was looking at the S_HVAC that could have worked too, but the slider is nicer for fine tuning. I wish I could have a fan icon with the Dimmer option in domoticz. Control by itself is working fine.

    I guess V_VAR is not adapted for that then. Too bad.

    I'm thinking of trying a S_DISTANCE using V_UNIT_PREFIX (RPM) and V_DISTANCE to send the values. It's kind of dirty but well.
    Maybe using V_UNIT_PREFIX with a S_CUSTOM sensor and sending V_LEVEL for the values is what seems almost the most intuitive, but it seems we can't do that.
    Any idea of a workaround solution using current sensors that could be accepted by the controller?

  • What about media player and volume to control fan speed?

  • Hero Member

    @emc2 No support for S_CUSTOM and the Prefix types in Domoticz. You need to stick to the known datatypes in Domoticz

  • Hardware Contributor

    @AWI I discovered it the hard way tonight. Lot of "Unknown sensor type" in my domoticz log.

    I have it working by declaring it as a distance, pressure etc. It's really dirty but at least for know I can track my RPMs. I guess I will try to poke around on the domoticz forums this week end to see if there is something cooking on their side.


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