This page last changed on Mar 04, 2010 by cevatt.

Hello All

We'd like to make a system that contains 168 lights, in 41 light sets, within 23 rooms.

We'd like these lights to be controlled by automation, from a Linux system we are developing. We aren't scared of developing software!

However we are finding no clear information about how to choose the right modules to control the lights, as everything seems to be tied into expensive 'integrators' - people that will charge thousands fof plugging a few bits together etc.

We're sure it isn't so complicated - the lights have a control module, the controle module somehow interfaces with an IP controller, and the IP controller can be talked to by a computer on the network.

We don't mind paying an electrician to wire up the dangerous bits, but want to design the control system ourselves.

The only questions are:

1. What modules should we use? KNX?

2. Can KNX work with switches on the wall as well as controlled from the automated system?

3. Is there a network connectable module that can control and return status all the lights from commands sent over an IP API?

4. Anyone got any recommendations on where to start?

If someone has some time to get back to me it would be absolutely great.



Hi Charlie,

if you only want to control lights and groups of lights you might want to look at DALI.
That is also a bus similiar to KNX but especially for lights. There exist gateways from KNX to DALI in case you need booth.

In case you want to use KNX you will need switch and/or dimm actuators depending on the lights.
You will also need a KNX power supply and one programming interface (RS232, USB or IP).

KNX normally uses sensors to send switch commands to the actuators. These are only connected to the KNX bus.
If you want to use already existing 230V wall switches you will need binary input actuators.
You can also control everything just from the computer and don't need wall switches at all if you want to.

Yes. No matter which KNX interface you use to program the KNX devices, this interface can be used to control and to retrieve status information.
If you want to use IP you should already use an IP gateway.

4) Define your requirements, look at possible solutions (KNX, DALI, DMX, X10, ...), read about the solutions or hire an "integrator" that does not want thousands of dollars/euros

Posted by mredeker at Mar 05, 2010 08:10

Hi Marcus, Thanks for the information, it's very kind of you to get back to me.

Do you have any example links to IP controllers/computer connected controllers that we could look into?


Posted by cevatt at Mar 05, 2010 14:53

What do you mean? What kind of controller? Do you mean a KNX IP-Gateway?

Posted by mredeker at Mar 05, 2010 20:49

Hi Marcus,

I'm James and I'm working alongside Charlie to implement this lighting control system. We had previously looked into DALI, but we are going to use the KNX modules to control over aspects of modern living (such as audio and visual, security etc) so that is why KNX seemed to us the sensible choice.

Ultimately what our beginning requirements boil down to is what equipment do we need to buy just to begin testing our solution? The ultimate solution of 168 lights spread across 41 different light sets needs to start somewhere, and we want to know where that starting point is.

To date we have mapped out each light (and it's position and type) on a floor plan of the property. We have then given each light an individual ID, grouped each light according to the room it's in, as well as what lightset it belongs to (ie kitchenuplights is a separate lightset to kitchenrecessed).

Now we need to know what equipment do we need to control just one light in one room. (We want to start the most simple way possible. Then we build on that).

Bear in mind that the property that will house the final solution has yet to be built, so there's no retrospective wiring, it can be done the most effective way right from the beginning. So our plan is effectively to set up a testing unit of 1 light in our workshop, that is controlled by a switch, as well as KNX equipment required to automate that light, both from a controller AND a browser window (IP control).

As Charlie has said, we are not afraid of software coding, it's just that we want to know where to begin with which modules we need to buy just to automate one light?

We really do appreciate any advice you can offer.

Kind regards,


Posted by jknottjames at Mar 06, 2010 14:00

Hi James,

for that amount of lights I still think that DALI might be a better choice. Do you also want to use low voltage halogen lights? The DALI electronic balast for halogen lights are much cheaper then KNX high voltage actuators. If you also want to use color LED this cannot be done with KNX but with DALI. You can always use a KNX<->DALI gateway to combine the lighting equipment with other devices like audio, visual etc. This is how I normally plan it.

To have a minimal setup to work with KNX you need the KNX power supply, a switch/dimming actuator, a KNX interface (either IP, serial or USB) and a sensor. In case you want to also look into the DALI stuff you would also need a KNX<->DALI gateway.

Where are you guys located? Maybe I can provide you with the equipment.


Posted by mredeker at Mar 06, 2010 16:49

Hi Marcus,

Thanks for the prompt response: we're based in the South East of England, in East Sussex. Where are you then? Are you in the UK?


Posted by jknottjames at Mar 06, 2010 17:34

I am in Germany. But since England also has 220V, I could probably provide you with some stuff. I am dealer for Siemens KNX devices.


Posted by mredeker at Mar 06, 2010 20:02

Hi Marcus,

In which case what would it cost me to order the equipment necessary for a minimal set up: (KNX power supply, a switch/dimming actuator, a KNX interface (either IP, serial or USB) and a sensor?

Of course it would be essential that anything I bought could be used to expand into the final solution?


Posted by jknottjames at Mar 07, 2010 00:35

If you provide me with an email I can send you an offer.
Also there is a pretty good online store that has a great selection on KNX and electric devices.

You can look there: EIBmarkt

Posted by mredeker at Mar 07, 2010 08:10

Hi Marcus,

In light of your recommendations for DALI, could we ask that you quote for a KNX system, then a separate quote for a DALI systems that manage the following:

12 lights in one room
There are 3 different lights sets (4 uplights, 4 recessed and 4 spot lights).
The lights need to be managed with a wall switch as well as IP control.
For UK electrics

Of course once we've tested and got comfortable with controlling multiple lights in one room we will want to expand the system to incorporate all the lights, so it's important whatever we buy at this stage can also be used in the final solution. Needless to say, we are trying to work to a very strict budget and this is why we are trying to implement the solution ourselves (as we are comfortable with a lot of what's involved here). Please reflect in your quote the bare essentials required to implement our solution without any optional extras. We just want to know what hardware is needed to begin, and although choosing the hardware is one of the most important aspects of the project, it has proved to be the most difficult!

We really do appreciate your help and I look forward to your quote.

Please send to:

Posted by jknottjames at Mar 07, 2010 11:06

Hi Marcus,

Have you had a moment to put a basic quote together?

Saw your home automation video at

Very impressive indeed. Seems like you're the right guy to answer a few questions!

Kind regards,


Posted by jknottjames at Mar 08, 2010 17:47

Hi Marcus,

Are you actively involved in Nomos? If so, I wonder how quickly you can move OR towards that perfection


P.S.: We have 230V since more than 20 years now!

Posted by kkreuzer at Mar 08, 2010 18:44

Hi James,

I am not the guy behind that video.
This comes from another company in Germany and the product is called m..myhome.
They also promote the same video on youtube.

All of us at OpenRemote are working to create something like this (and better )

@James: I am traveling the whole week but will try to put something together tonight.


Posted by mredeker at Mar 08, 2010 19:33

As a KNX Integrator/Tutor, I'd have to recommend DALI as well for this sort of lighting control. You'll find it's rather flexible in the long-run. While I'm not familiar with Siemens' offerings, seeing as they don't actively sell KNX in South Africa, I would strongly recommend either a Hager or GIRA DALI Gateway for KNX. They are actually the same device, manufactured by Insta. (Insta only sell through their OEM partners ... I've tried

The reason I would suggest this product is that it allows for 64 DALI Devices in 32 Groups. 16 of the Groups can contain multiple DALI Devices, while the remaining 16 can hold one DALI Device each. This is, from our experience and research, the best solution we have come up with. ABB also make DALI Gateways but are VERY limited as far as Groups. (Either 1 or 8, depending on the KNX Device ...) For your application, I don't think this is worth it.

Your best bet, being in the UK, would be to contact a local KNX Distributor; thankfully, you've got one of the best there: KNXshop (

I would recommend giving them a call and speaking with Colin Price. He will be able to direct you. If you need training on KNX, they provide it themselves.

For IP Control of KNX, there are many devices that you can use. It depends on what you want to control it from, and how:

1. Tapko ( have just released a USB Device that allows you to send KNX Bus Telegrams straight from a computer.

2. Weinzierl ( have just released a KNX Stack for Linux, which would make Linux-to-KNX development easier.

3. Weinzierl also have a number of KNX IP devices that you can check out, with Object Servers, Tunnelling, blah, blah, blah. Lots of options there.

4. You can stick to OpenRemote as well ... they've done a LOT of work and, frankly, there's no reason to start from scratch when you can add to a community project.

The difficulty is that there is always more than one way to skin a cat, so different people will approach your requirements differently. Mine is personally to not reinvent the wheel. You may seem to save money short-term, but have more headaches and, ultimately, lose more money long-term.

Hope this helps.


Posted by jeanpierrej at May 13, 2010 15:50

Hi Jean-Pierre,

Thanks very much for your detailed reply: so you would recommend DALI as well. Will DALI deal with low energy bulbs as we're less inclined to use Halogen?

And what sort of costs do you look at: I've got about 64 groups of dimmable / dimmable lights, some of these groups being as small as 1 light, some as many as 10 lights - all spread over about 13 rooms (and outside).

Kind regards,


Posted by jknottjames at May 13, 2010 20:41

Hi James,

You're very welcome. The one thing with DALI to be aware of is the Transformer/Ballast costs. As they are intelligent control devices, they tend to be priced higher. This is mitigated by the amount of flexibility the system offers.

The way to work out what you want to do is to detail the following on a spreadsheet:

1. The Full Circuit (How many globes & the wattage of each lamp)

2. Mark whether you want it switched or dimmed. (I would NOT recommend mixing the two for control purposes ... it'll be confusing)

3. Mark what type of lamp(s) are being used, i.e. CFL, Standard Fluorescent Tube, Halogen, Plain White LEDs and/or RGB LEDs.

You can dim all of this with DALI, so no worries there. Once you have this information, then you know how to break up the Circuit into DALI Devices. This is the general rule of thumb that we use, though it can vary:

1. If using CFLs, count one DALI Device per bulb.

2. If using Halogen, count one DALI Device for every 150W.

3. If using Standard Fluorescent Tubes, count one DALI Device per Meter. (You can usually get two tubes per Ballast)

4. If using LEDs, count one DALI Device per Meter. (Applies for both White and RGB)

While others might disagree, I would highly recommend that, out of the big boys, you stick with Osram as a Transformer/Ballast manufacturer. Tridonic is, at least locally, cheaper than Osram but you pay for it in the long-run with Transformer/Ballast failures. Once they work, it's great, but we've seen too many duff units from them to recommend them at all. We've not had any troubles with Osram, however.

Next, you mentioned Outside lighting. Generally speaking, we don't bother with DALI outside and rather stick with standard KNX Switching Actuators. (Relays) This is really since the DALI Transformers/Ballasts are generally a little bigger than your cheaper items and, frankly, why would you want to dim something outside? Unless it's downlights in an overhang/balcony ceiling, and you REALLY want to create a mood on a patio below it, there's no point.

If, however, you do want to create a mood outside, I would recommend using a standard KNX Dimmer for those lights as the Transformer size can then be smaller. MDT ( are releasing a new Dimmer come September/October that will have a minimum 3W Load (as opposed to 50W for all other KNX Dimmers I know of) ... and it will dim:

1. Incandescent

2. Halogen

3. Dimmable CFLs (like Megaman bulbs)

4. Dimmable LEDs (using, for instance, a Osram OTi Easy Transformer)

Just realize that it has a max of 250W per circuit which seems small but is, actually, quite normal. (5 x 50W Halogen Downlights) If you are sticking with Incandescent/Halogen and have a larger load, up to 1000W, I'd recommend Hager Dimmers. They have a 3 x 300W Dimmer that is especially nice as the channels can be cascaded, meaning you can have 3 x 300W OR 1 x 300W + 1 x 600W OR 1 x 900W.

Lastly, the only thing I would highly recommend with DALI if using Halogens is to check what the wiring specifications are in the UK. I only know rules in South Africa and they may differ greatly, but since Halogens are Low-Voltage, (LV) if the Transformer isn't close to the light(s), wiring coming OUT of the Transformer to the lights needs to be rather thick to deal with the extra heat generated by LV. Locally we've got regulations stating how far away from the Transformer the light must be as SA has had lots of, shall we say, "less-than-qualified people," wiring with too thin a cable, resulting in the house burning down. So, check with your electrician about this while making the spec.

Hope this helps. Lemme know if you need anything else.


p.s. For LEDs, avoid cheap Chinese Transformers. We had a visit from the Osram Product Manager in Germany where, among other things, he mentioned how Chinese companies tend to stamp LED Transformers as SELV, meaning you can touch the LV with your fingers and not die. However, they just stamp the items without actually introducing the appropriate circuitry. As a result, especially in Pools/Wet Areas, there is a high risk of electrocution due to the missing circuitry.

Posted by jeanpierrej at May 14, 2010 07:42


It's been a while since I last posted, as we've been right in the thick of the build... but I've finally got to the stage where I'm putting in the wiring / electrics / lights etc, and the one thing that has become obvious, is that the money I was hoping to have available for light / home automation is just not there.

Instead what I'm going to do is install knx cable to each light switch in the house that I want to automate (including dimming), then once I've got the money, connect it to the switch and buy the appropriate modules...

Overall I'm going to have about 12 different light sets that will need automation, so I will just run the KNX cable to each switch, then bed it in the wall behind the plastering until a little further down the line when I have the money to install it.

My questions are:

1. how is this KNX cable attached to the light switch? Do I use the normal light switches, or do I need to buy custom switches for this?
2. my electrician is wiring the lights / electrics as it should be wired in the UK, with a permanent live feed to each light that is controlled by the switch. Seeing as though this has already been done, I can't change it. So if this isn't right, then I assume there's no point me running out the knx cable!?
3. can I run this KNX cable out to other points? For example, lay out some spare KNX cable for integrated music, movies, tv etc?
4. For my internal network I'm running out CAT 6 cables (about 18 network points so far). This has all now been installed, but I'm assuming I can't use this instead of using the KNX cable?
5. These KNX cables are being run direct to each light switch from a central hub located under the stairs in the basement. In the same room is the fuse board / electrics etc. It will be in this room that the modules will eventually be housed. So how does this part of the install work?

I'm sorry these are such basic questions. When you're doing a house build there are so many things going through your head, it's a surprise you're able to sleep at all!

Anyway, any help / guidance would be appreciated.

Perhaps it would be wise for me to rewrite this question as a new post?

Kind regards,


Posted by jknottjames at Aug 09, 2010 10:16

I've actually begun a new topic thread using my last post as the starting point...

Posted by jknottjames at Aug 09, 2010 10:28

Hi Marcus Redeker
please i need documentations witch contains the architecture of the KNX but in French
if you can guide me
thank you

Posted by hakima at Oct 14, 2015 10:47

Hi James Lambert-Knott
please i need documentations witch contains the architecture of the KNX but in French
if you can guide me
thank you

Posted by hakima at Oct 14, 2015 10:49

You find french information on and
If the spec is available in french, I don't know but that is not free anyway.

Posted by mredeker at Oct 14, 2015 14:56

Just to throw a curve ball in, for anyone reading this thread in the future.

Velbus modules would be an excellent alternative.

Posted by mdar at Dec 30, 2015 12:14
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