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  • I am about to start a new build house and want to build the smart home installation around the Unipi Axon. I’m pretty confident that most requirements will be covered, the only thing I’m less sure about is the dimming circuits, especially RGBW dimming. All the lights will be 24v LED and there is only one circuit that is RGBW, the rest are simple white light.
    Basic Requirements:
    Lights – Dimming= 10 ; Switched= 25
    Sensors – Motion= 16 ; Temp &Humid= 8 ; Light= 6 ; Window cont.:= 7
    Blinds= 6
    UFH zones= 5

    Unipi Hardware:
    Unipi Axon L505
    Unipi Ext. xS50
    1 Wire 8 Port hub
    Power 24V 1.5A

    What would you guys recommend for dimming circuits?
    The documentation claims the Axon range is Dali compatible but I’m not sure what hardware would be required to get this set up.
    I found this 8ch LED Dimmer (0-10V, DMX, Modbus) which I think would be manageable through the Axon AO’s but this is no longer available.
    Would something similar work?
    Maybe something like this from anigmo?

    None of these cover the rgbw circuit though....

  • administrators

    Hello @lessmann,
    all of that looks like it will be manageble via our PLCs. What SW do you plan to use?

    As for the dimmers: both of them looks like they could be used. Try looking for drivers which can be controlled over Modbus, 0-10V or 0-20mA. The DALI is quite complicated to setup right now, although we are working on a SW implementation which can be controlled over ModbusTCP. The DALI-enabled PLC is currently an Axon S605, lacking other IOs:
    You could try looking into DMX controlled LED drivers and use it together with OLA project: But that will also require quite some amount of time to get it work. I can send you some proof-of-concept settings.

    Best regards,

  • Thanks Martin

    The lighting will be 24v led strips with maybe a handful of spotlights.
    I think the only solution is to buy one of the PLC’s and start playing with it. For a newbie in the PLC market there really is very little documentation online to get one started. I have been making things with arduino’s and raspberry pi’s for a couple years now and if you are relatively tech savy and willing you can teach yourself but this wealth of knowledge is lacking when it comes to PLC’s...

    Thanks for the heads up on the axon-s605 but like you say it looks like a bit of a challenge at this stage. I’ll keep it in mind once I’ve mastered the basics!
    I’m a long time user of Home Assistant and very much want to make HA the interface for all the control and automations in the new house. I’m surprised there isn’t a bigger overlap between the unipi and home assistant community. Maybe we can remedy that in the near future....

  • When it comes to expanding the I/O’s, and instead of using the Extensions, is it possible to have multiple PLC’s to increase those or will I have to access each PLC individually? Is this where the Modbus Master/Slave setup comes into play?

  • administrators

    You can use PLC as an ethernet extension. You can reconfigure the unipitcp service to listen on instead of thus making it publicly available. You can have one PLC running the program and acting as master.


  • Thanks Martin.

    I would be grateful for your advice on the following hardware choice.

    I have a rough estimate of what I/O's I'll need and the hardware required to cover that initial demand, now my query is this:

    Is it better to have a small PLC with many Extensions or a large PLC with only a few Extensions? The advantage of the smaller PLC being that less can go wrong with the PLC which is the most critical item and should a relay break for example it would be simpler to exchange an Extention rather than a the PLC. Also there will only be local disruption instead of the whole system going down if anything malfunctions. The only downside is that I suspect the smaller PLC route will cost more.

    I guess I've really answered my own question there....

    Regarding the RS485 connection, I recall the documentation stating that a maximum of 6 Ext.'s can be connected to one BUS, please ignore my ignorance but is one BUS one RS485 connection?

    In other words if I have 2 x RS485 connectors i can in theory connect 12 Ext.'s?

  • administrators

    Hello @lessmann,
    the limit of how many devices can be connected to one RS485 line comes from the RS485 transceiver (the chip on the RS485 output) and on our PLCs it is 32. But be aware, that this is just a theoretical limit and the real limit depends on the current situation.

    Second limit of the RS485 is the speed of the communication. Since RS485 is a half-duplex type of communication (master can speak only to one slave at a time), the more devices you have the lower speed of updates you will have.

    If you have PLC with more RS485 ports, you can split the extensions into groups.

    Best regards,

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