No KUX, just Loxone

Integration of Velux roof components into home automation systems has been often criticized in many smart home forums [1,2,3]. The usage of proprietary protocol is making this “black box” difficult to integrate and
to interact with any other solutions. The overall architecture is a bit weird, utilizing a control unit KUX 100 which is receiving the IO radio commands and then sending these to the window over the 24V line. There are several drawbacks, like space requirements, stand-by consumption, price and scalability. Moreover, who wants to have a box full of remote controls these days, or a separate mobile app for each of the device you have at home? That approach is similar to the so called “smart bulbs” you control over an app in your phone to give you the “(not a real) smart home” feeling. 🙂
I am sure you are familiar with some of these limitations because you reached out to this post. Let’s have a look how I integrated my Velux equipment (Shutters, Rollers, Power Windows) in the house, without the KUX 100 or 110 control unit.

Velux Roller Shutters

I have two rooms with Velux SML shutters. Now it is important to say, that all these Velux products are expected to be controlled by their dedicated control unit, for instance the already mentioned KUX 100. The problem with these units is that they only listen to the paired remote, and the device is not designed to accept any external commands. This makes it extremely difficult to connect to any master system. After some research I learned that due to some compatibility reasons these shutters can work in a polarity driven simple mode without the control unit.

Known fact is that once you connect the shutter to the original KUX controller, since that moment the shutter no longer listens to the polarity change and expects KUX to give instructions. There are several guides found on internet about how to reset the shutter from the “smart” back to the legacy mode working with polarity reversal (+-24VDC).

Velux Roller Shutters (SML) - closed
Velux Roller Shutters (SML) – closed

In my case, one of the four shutters I installed refused to follow the legacy polarity control. We can just speculate about the reasoning here, it could be that someone have tested that piece before shipment and thus the roller was already connected to the Velux KUX control system which enabled the “smart” control modulated on the power-line.

This is a critical scenario. I did not find a way how to reset the roller without the KUX unit. So I had to borrow one just for the purpose or the reset procedure.

If the motor has been connected, it can be reset in the following procedure:
* Connect and apply voltage on the KUX 100
* Press 5 seconds on the reset button of the transformer, not the remote control
* The motor will enter a test-run
* Disconnect the supply before the motor quits the test phase (after ± 2 seconds)
* After that the shutter will work on any 24VDC polarity change

Original here, author Pedro

But there is one more interesting thing I was not aware of. If two or more SML shutters are connected to one power supply, they immediately stop. It has nothing to do with the load, but it seems that there is built in protection avoiding hooking more than one window to one KUX. Once the shutter listens the modulated signal of the other, they both refuse to work until you switch off the relays or power supply, and enable just one of these to complete its function. So in reality, if you are planning to hook all shutters to your industrial 24VDC power supply and control these via relay boards using the polarity change, you may need to go over an additional hurdle.

The thing is that the modulated control signals needs to be filtered out. I have been experimenting here for a quite a while, and I have two workable solutions. Both require to mount filtering device directly in the upper window space, where the connections are fit.

  • Option one is to use ready made filtering module board from an old computer power supply. It usually consists of one twin-coil chokes (coil for each of the input wire) and few capacitors. It works with AC so it is polarity friendly. The advantage here is that these boards have higher total current limits and are pretty solid. You connect both input wires through the module and take the output from the other side into the shutter.
  • Option two is to purchase coil chokes (two single ones for each window, or one double) and connect each wire through one coil. Please make sure that the Imax current limit of the coil is higher than the consumption of the shutter. Few examples here:
    • Talema 42V3020, 2 x 5.6mH / 2A, Rdc(max) = 0.17 Ohm [datasheetlink]
    • Talema DPO150A1, 150uH / 1A, Rdc (max) = 0.123 Ohm [datasheet, link]

Both are very small electronic parts (size of 3 cm or similar), so it is relatively easy to put these between the connection points of the shutter. And yes, there will be slight voltage drop caused by the resistance, but you won’t notice any difference during the operation.

What it does is it eliminates any high frequency signals from the line, passing just the DC voltage there. This way you isolate the rollers that are connected to the same source. If you have 2 rollers, it should be enough to put the filtering module just to one of these, but I finally added it into all of the rollers, there is plenty of space for that.

The Velux Roller Shutters is one of the best products for these windows in my opinion. It has a clever design, allowing the window fully open when the shutter is open, and limit the opening angle only when they closed. But still you can have the window partially open when the shutter is closed. They do remember the end positions from the test drive and return smoothly back to these. Apart from the closed communication protocol I already mentioned, this is a reliable and robust product, I must say.  I never had an issue with these since 2015.

Velux Blinds

Velux DML (indoor electric blackout blinds) are the easiest to integrate. These are simpler devices so the problem of not having KUX controlling device is not applicable here, or at least I didn’t have any issues. You can easily control these using 24V polarity change. The only trouble that might appear is again the protection against multiple blinds on one power source. If you experience such issue, the same steps needs to be taken using the current chokes. This really depends on the individual installation, cabling lengths and type as well as the PSU type. I have three windows with these Velux DMLs, and I had to install chokes only after I did some rearrangements in the cabling and power supplies.

Velux blackout blinds (DML)
Velux blackout blinds (DML)

One recommendation here

If you are considering the options how to reduce the sun heat in your rooms, or even if you just look for options how to make your bedroom completely dark, in both cases go with the external roller shutters rather than the internal blackout ones. I know these are more expensive, but the quality and durability is on a higher level. And more importantly, the inside blackout blinds does not help you reduce the heat much. They do ensure total darkness, however the heat radiates inside of the room! The only time when you can get into troubles with the external roller shutters is when you get a lot of snow. Only then there is some advantage of having the indoor blinds, which are not impacted by that. In all other situations the roller shutters are better.

Few issues with Velux DML electric blackout blinds

Also, I think is fair to say here, that during the last three years I had few issues with the Velux DML’s. After a while they started to jam the fabric randomly, so I had to call the warranty service guy who has been trying to resolve that. Although we selected premium fabric, there are already few small holes in it. I have no clue how these happened, as we control these blinds only electrically. If I had to choose again, I would go with the external roller shutters SML,rather than these DML.

Velux motor KMG 100 WW

And here is the most difficult part. Some of my Velux windows are equipped with the KMG 100 WW motors from Velux. These allow automated opening and closing of the windows that cannot be reached by hand. Unlike other Velux equipment (Shutters, Rollers) which are easier to connect with Loxone, these motor actuators cannot be easily controlled via polarity change +/- 24V. The reason I heard was security or safety, but in reality Velux wants to sell their own solution, which is unfortunately not friendly to any other systems. The only way I found to integrate these roof window electric motors is to order third party PCB and replace the original board in each or the actuators. I ordered the VNX modules here. It fits perfectly into the original housing and works like a charm. Kudos to
Michał Byrecki for his amazing job!

Velux motorized window
Velux motor KMG 100 WW installed

The installation is simple and is well described in detail in the manual. You just open the plastic case, unsolder two wires, exchange the modules, solder the motor back, assemble back the case and voila, now you can control your window opening motor using the polarity change of +/- 24 V.

Original Velux board on the top, alternative from Techniline below.
Original Velux board on the top, alternative from Techniline below.

The new board still preserves the original functionality of reducing the chain and gears tension by reversing the direction for few steps at the endpoints.

With Loxone you can also use the micro-ventilation feature of Velux roof windows, that can be set-up in the blinds control module as a “shade” option (parameter “Tr”).

Slight downside you might mention is that you obviously loose any warranty as soon as you open the original motor housing, and also the additional costs (49 EUR) associated with purchase of the driver unit. But it is definitely less than you would have to spend on other extras in order to make the motor work with your system. I am using this solution since summer 2015 and I haven’t had any single issue with that.

Please note…

Finally, be aware that commercial products evolve over time and what I tested in 2015 might not be applicable to any potential newer revision of the same device. I always recommend to test or check your planned setup before you make any bulk orders.

Connecting to Loxone

Switching of the Velux components is managed using Loxone extensions with relay outputs (red connectors on Miniserver, Extension or Relay Extension). The only additional component you will need is reversing relay, which is needed for switching the polarity of 24V.  It can be done without it, but let me explain why is it better to use that.

Loxone components are not prepared for polarity switching output. To make this happen, we need to either use four Loxone relay outputs for each component.

Here is an example how Loxone can control DC motors which are often used with blinds, awnings and curtains. As you can see, it uses four relay outputs.

Or we can use only relays outputs two plus additional reversing relay. If for instance we have more windows in one room and we do not expect these to go the opposite direction at the same time, we can save few relay outputs by creating a group of blinds or shutters, but still preserve the option to control each individually if needed.

Here is how you Loxone can control the polarity change relay and individual DC motors.

Here is how you Loxone can control the polarity change relay and individual DC motors.

I have my roller shutters and blinds connected using the reversing relay. So if a room has three windows, I am using just one reversing relay for all three, and then just three individual outputs for each motor. That makes me use 4 Loxone relays and one external reversing one,  compared to 12 if I would follow the upper diagram. The only disadvantage is that I cannot run blinds the opposite direction at a time. But this I identified as very rare scenario.

As an external relay I am using Finder which consists of three parts: 24VDC relay coil with 8A contacts FINDER, a base for DIN rail mount FINDER 95.05 and a clip holding these two pieces together FINDER 095.01


Programming in the Loxone config is just an additional logic around the blinds control block. If you want to be extra finicky, you can also add controlling logic to prevent opposite direction runs of multiple blinds in one room (connected to one common reversing relay).

Velux motor config

Please note that the above config maintains just the basic functionality. There needs to be additional programming done for rain protection, as well as central functions. This probably deserves separate post.

Velux blinds config

The blinds modules are configured for two windows here, can be controlled separately in the app or joint using a wall switch.

I hope this might help someone when considering the options how to automate and control the roof windows accessories.


  • This is so great that you shared this info!
    Unfortunately the links to the VNX-driver and manual seem to be offline. Is the module maybe not up to date anymore for the newest Velux windows? Would you know an alternative for this replacement module ?
    Thank a lot

      • Hi Bart,
        well how to say that… Now I know what is behind, the modules are (and will be) available, however there has to be done some forced update in the doc and web presentation. I believe the info will be back online soon, please stay tuned.

          • I just checked the Techniline website again, and the manuals are back online. They now contain some forced warnings about the implications of the HW modification (requested removal of CE certification, and so on..).
            It is interesting that Velux is going after these HW customizations rather than making the device open and naturally compatible with multiple systems.

  • Hello,

    Just discovered Techniline products. Looks they also designed a replacement board for the wired Velux blinds (VNX-ADV).

    Mine were all delivered in the legacy +-24V mode: Looks Velux sales are aware of people that do not want to go the closed-IO way. Installer that accepted to plug mine on existing wires (from the 1990’s, with a global 24V supply under the roof and one polarity reversing switches per blind) did contact Velux to make it clear, as some other installers did not accept (saying IO was now mandatory) the job, saying this was no more possible…

    So dit not had to change blind engines control boards, but that’s nice to know if I have problems someday.

    Did not experiences issues as well with 4 blinds on the same power supply: No filtering was needed.

    Only issue is new blinds looks to be more power hungry (or power peak sensitive) than old ones: Could only switch one at a time, like you.

    Even having one switch still powering it’s blind (up or down, but blind not moving anymore because full open or closed, thus maybe using only a few mA) because not both in neutral position was enough to avoid others to operate. Simultaneous was working with old blind.

    => As I didn’t think this may have been some IO over power line issue between blinds, I changed the old power supply for a new one (industrial 80W, din mounted) and simultaneous operation worked again for 4 blinds. Old power supply was 30W.

    IMO, the blinds control board is put in reset till next power cycling if powering requirements are not meet (preventing any movement when old blinds were able to move, maybe a bit slower) and as power peak will occur at blind engine start, I think your filtering may just smooth the voltage drop seen by the control board and allow operation even if your powering is a bit underestimated.

    If you have at least 20W per blind of installed power, I may indeed be wrong & lucky because my power supply does a nice output filtering!

    I use this device: TPC 080-124 24

    OK since 3 years, even inside a non isolated (thus a temp range of -20°C/55°C) attic side over the upper floor.

    This device, when no load is connected (all blinds up/down switches in neutral position), only use a few µA as well. Far from Velux IO equipped power (~5W idle per supply, thus per blind when you want to keep separate controls).

    Only issue that remains is low stop position have moved a bit on 2 blinds over years, maybe 0.5cm from the end. As there is no more blinds reset available (a procedure that have existed and can be found on the net did not work for my end-2016 blinds), without IO I have no way to trigger a new stops learn procedure.

    Velux would better clean it’s mess than firing it’s legal teams to those that try to fix their bad design (closed radio protocol + stupid architecture, with radio inside the power-supply thus not compatible with existing roof wiring).


    • Hi,
      I really appreciate your detailed post. Thanks a lot! My blinds operate flawlessly for couple of years now so I haven’t been investigating the interference details any further, the filtering did the job. The PSU I am using is 240W MeanWell HLG series, so I doubt the instability reasoning, but I might be wrong. It could be also the wires that are very long in my case.
      The low stop position is something I have noticed as well, probably same impact as yours. It is interesting that this is being visible only by one of my four blinds. To reset it I would need to borrow the KUX brick somewhere. It is pity that it cannot be done some other way.
      The overal Velux approach is a bit weird. With the expanding trend of households being controlled by central systems, sooner or later people won’t primarily look for Velux products because of the integration hassle. Similar approach is inevitable in the HVAC and home audio, where some companies got the point (Daikin, Denon, …) while others will gradually wind down with closed proprietary solutions.

  • Hello,
    I decided to buy Velux windows with SHL shutters.
    Could you pinpoint the coil chokes you use in your env? Proposed Talema is oparting at 240V AC, so probably won’t work in our 24V scenario.

    Best regards,

      • we are operating on 24VDC so I assume that coil dedicated for that power supply should be used? I have ever used these coil chokes 🙂

        • Check if the whole setup works without anything additional first. It can happen, that no filtering will be needed. This is really case by case considering the PSU type, wires length, and so on. If this doesn’t work (meaning that you’ll not be able to operate more shutters simultaneously), then experiment with the chokes. To simplify, the choke is there to pass DC and filter out AC. It is recommended to study technical background to prevent any risks of damage. For you the limiting factor there is not the max Voltage the choke can manage, but the max current it can handle through!

  • What a nice post Kops, this is very usefull.
    In my situation there’s 2 Velux SML shutters. Tried to test with the polarity change, but:
    when i leave 24VDC on it either way the shutter just fully opens, to continue to fully close, and when fully closed again fully open and so it goes on. Is this common? Do i just need to put right timing in this? in other words, would like to be certain to be opening the rollers in an emergency situation, and because i want it to work the right way 😉 many thanks for this article!

    • Hi Tiesel,
      interesting findings. So you are saying that after you apply 24V DC the shutter will do one move and once it reaches the end it changes the direction immediately? And this repeats on the other side as well? Isn’t this just the calibration run the shutter does to get the end positions? Does it dynamically slow before the end points or does it reach the final position at full speed (bump!)?

    • Hi Tiesel,
      I have same problem in one of 5 windows… and it was working 7 years without issues and now this is happening. Did you solve this? How?


  • In addition to my previous post, apart from using 4 relay outputs per window, are there any cons? For the 2 windows i need to plan 8 outputs, which should be no problem.

    • I am using the reverse relay (as described in the post) per each room to save the Loxone relay outputs, but otherwise it should be OK. I would recommend to put some fusing mechanism in the circuit, because the polarity change controlled by individual relays can under critical circumstances (relay failure) cause short circuit of the PSU output.

  • Hi,
    I am buying there Solar Powered Shutters, so this solution will not work for those.
    But what about modifying the wireless controller?
    I saw a post about doing this on the old pre-2014 controller. So long as you can identify and connect to the switch contacts, all you have to do then is buy a couple of smart mini switches, on for up and one for down, and connect then in to the switch contacts to simulate switch operation.
    Seems a far simpler and easier solution, and a universal one that would work with solar and mains powered products.
    Has anyone looked into this?

    • Wouldn’t be then easier to use KLF 050 / KLF 200 and integrate these “wireless” windows through these? Not sure how these are positioned cost-wise.
      Integration with Loxone

      • Yes it would be easier in not needing to modify a Velux remote. But it still needs external relays to provide smart control via the KLF200. So might work out more expensive depending on numbers of Velux devices to be controlled.
        I will check out the KLF50. Hadn’t head of that.
        Btw, with Active you can ask for Windows to open only to the Locked Ventilation position. I wonder whether that’s possible with KLF200.

        • Any idea whether the “Velux Active with Netatmo” can be controlled via HTTP strings or similar? That would be great so there would be a way to control the damn Velux Integra windows using Loxone native control incl. temp/hygro monitoring which is already in all the Touch switches…

  • Hello,
    I have 5 of SML rollers and using inels.
    As written in article I did not like “smart” control from velux as it did not work with Inels that time at least.
    So it is controlled by switching polarity.

    Now the current problem.
    One of the rollers is rolling and does not want to stop where it should. Other windows are fine. Relays seem to be working correctly.
    It looks like it needs some re calibration or something.
    How to fix it? Electrician is gone and velux might not help here.


      • Hello,
        update: the window got to calibration status by itself… in the last few months all other windows did same… so I am not sure what and how it did it… Motor might have some timer to do it by itself?
        I figured out that my window could not calibrate as I was sending power only for 30 secs so it did not find all positions… I removed the time limit and it calibrated and it was correct.

        But problem is that now one window got to calibration mode and there was snow on window so it got calibrated in the middle of window by accident.

        So I like to know how to force that status again without KUX 🙂
        Is there some special current frequency that needs to be sent or some timing and sequence of controls that will initiate?

        • Hello Dino. This is super interesting finding. Would you mind elaborate a bit more on how this has happened? I mean the calibration.
          Is this happening on the way up, or down?
          Does it then make complete round trip (e.g. Down, and then Up and Down again)? How often does that happen? Once a month, half a year,…
          Finally, how did you implement that in Loxone? I tried simply to extend the time for the up and down to some insane number like 30minutes, but after few cycles still no luck to trigger any calibration. Also, this kind of implementation causes few drawbacks, so I would need to find better way how to keep the motors powered longer after completing the run while keeping the time in the config block real.

  • Great information provided.

    I’ve got Velux Solar windows, and due to the solar panel / rain sensor being changed in 2014, Velux tell me I have to upgrade all the motors and panels to the latest versions as the existing rain sensors on the solar panels have broken.

    I have four windows, so that’s very expensive. As a result I’ve decided to ditch the solar, and use a standard power supply to all the roof windows. This is fine, but now I need to connect the rain sensors to the existing window motors (863695). I’ve checked the motors and they run at a voltage range of 10.8v to 18v DC at 8w.

    Does anyone have the three wire pin-out for the Velux Rain sensor (941120 – 3LA A01 WW)?

    Even better, has any one already done this, and have a diagram of the wiring needed on the 6 pin Molex connector?

    Thanks in advance, and fingers crossed that someone can point me in the right direction.

  • Hi, I’m wondering if you know what is the maximum voltage sml shutter will work with.
    I have a 24 vdc instalation with ups batteries so the actual level is around 27vdc

    • Hi, just to let you know that recently bought SML Shutters still work in Legacy mode and it is still not possible to control more than one without any filtering.

    • Hard to tell. Typically there is some tolerance. I know people run the whole Loxone infrastructure on about 27 VDC. It also depends on the wiring, if you have long wires to the roof the voltage might drop on the way a bit as well. So 27 V could be all right, but you never know.

  • Hi,

    I have the old WCM 531’s with infrared. Anyone any experience with just connecting a KUX unit to these without having to buy the motor again? From what I have read you just need to be able to reverse the polarity, I am guessing that’s all the KUX is doing? I am worried that I wont be able to get the rain sensor to work correctly. I also see no reason why a “Z-Wave Qubino Flush Shutter DC” wouldn’t work, though I guess you will loose the ability for a proper remote? Would love to hear from people before I take the plunge and buy a new motor!


    • I admit I don’t know the answer here as I don’t know how WCM 531 worked. However, KUX is not reversing the polarity. Once you connect KUX to the compatibile shutters, these will switch to different operation mode. They will get the power from KUX, but the control will be done over that line via some “data” transfer. After that the shutter won’t react to polarity reversal operation any more, unless you follow the reset procedure described in the post.

      • Hi, thanks for this. Is there just two cables connected from the KUX to the motor. Struggling to see how is sends data to a motor. Though I guess the motor has a board on. Maybe it’s sending a pulse of electricity or something..

        • Data are sent over the same pair as the the power. But there is no datasheet or protocol publicly available as far as I am concerned.

          • I recently bought 11 dml indoor screens, hoping to control them with the polarity switch mode. I powered the screens, isolated from the rest, for 24h in both polarities, but i see no reaction. I bought a kux110 to try resetting the screens as per the info in this article, but again no reaction using the legacy mode. They do move to their starting position when powered with the kux, so i assume everything is wired correctly. Is there something else i can try, or do I have to settle for the closed system Velux tries to push?

  • I recently bought 11 dml indoor screens, hoping to control them with the polarity switch mode. I powered the screens, isolated from the rest, for 24h in both polarities, but i see no reaction. I bought a kux110 to try resetting the screens as per the info in this article, but again no reaction using the legacy mode. They do move to their starting position when powered with the kux, so i assume everything is wired correctly. Is there something else i can try, or do I have to settle for the closed system Velux tries to push?

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