KNX Standard Confounds American Who Wrote the Book on Home Automation

Grayson Evans, who wrote the book on CEBus way back when, shares his five years of experience with the EU home automation and building control standard KNX, and considers prospects for the U.S. in advance of CEDIA Expo 2015.

KNX Standard Confounds American Who Wrote the Book on Home Automation
KNX home automation and building control standard architecture: Control devices are daisy-chained via a two-wire bus to a main panel that connects to to the powerline and the loads. (Image: Smart Automation)
Grayson Evans · September 16, 2015

The following article comes with a few caveats. I am not an expert on KNX. Everything I know about it comes from five years of personal hands-on experience with existing installations and a long history of designing and working with similar technology for building control ad home automation. My experience is primarily limited to Turkey with limited exposure to systems in Germany and the U.K. - Grayson Evans, [email protected].
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There’s a big push to bring the popular European building automation standard KNX to the U.S. This year, the KNX Association is bringing a booth to CEDIA Expo 2015 in October for the first time; a new company called DMC Technology recently established the country’s first certified KNX training center, run by one of the world’s preeminent KNX educators Marc-Antoine Micaelli; and Siemens, the only major KNX manufacturer in the U.S., wants some company.

Will the effort work? Doubtful.

To understand why, let’s look at the fundamentals of KNX and the particulars of the EMEA (Europe, Middle East, Africa) home-control market, vis-à-vis the U.S.

The concept of home automation is quite different in EMEA compared to the U.S. In EMEA it is more “control” oriented (lighting, a little HVAC, blinds/curtains), whereas in the U.S. it is more entertainment oriented. This explains the popularity of KNX in Europe and the Middle East.

When I arrived in the “ME” part six years ago, everything that claimed to be “automated”, mostly commercial buildings, was using KNX as the basic technology. Since then, it has gained wide popularity in new residential construction. The odd thing is, in residential, it is seldom used for any type of automation.

There is a reason. More on that shortly.

Explaining KNX

Since it’s a mixed evolution of EIB, European Home System Protocol (EHS), and BatiBus, I was familiar with the technology from my days of working on CEBus and LonWorks.

Devices that are KNX-enabled fall into two general categories: sensors (switches, light sensors, temp sensors) and actuators (relays, motors, dimmers). All devices are connected together with a two-wire differential signal bus (RS-485-like) at 9600 bits/s, plus two wires for low-voltage power.

The standard incorporates RF, powerline, IR, and other media, but I have never seen anything used other than twisted-pair.

RELATED: Will KNX Home Automation Standard Make it in the U.S.?

Every device on the bus has a field configured address and one or more group addresses (of which it is a member). When a device changes state, such as a light switch going from off to on, it transmits its new state to another device address or a group address. Transmitted data can be binary (0/1) or an 8-bit analog value. On the plus side, it is simple and doesn’t need any type of controller. 

A typical residential KNX installation looks similar to some “panelized” lighting systems in the U.S.

KNX switches are wired together, daisy-chain fashion, on a 4-wire bus back to the home’s load center. There, the companion KNX lighting load modules (on/off or dimmers) are also wired to the 4-wire bus and connected with conventional 220V electrical wire to the light fixture.

During installation, a specific software application called ETS is used to give each KNX device an address and to “bind” it to another KNX device or devices. In this case, the switches send their state to a load control KNX module. Once set up, it operates no differently than conventional electrical wiring. Of course, a switch could be programmed to control a group of loads. Switches can also receive data to their address to turn on a status LED for example. KNX-compliant devices are manufactured by every major European electrical equipment manufacturer (ABB, Siemens, Schneider, etc.)

KNX architecture (image: Schneider Electric)

KNX installations fall into two categories: standalone (no controller), or with a controller, as a subsystem of a proprietary automation system. A controller is allowed in a KNX ecosystem, but is not part of the standard, per se.

In either case, I have never seen KNX used to automate entertainment or more complex systems. It is always used to control lighting and sometimes curtains or blinds. There is not much HVAC control because HVAC equipment over here is a nightmare (hope that never comes to the U.S.!).

Every installation where we go into an existing home with KNX, we use an Ethernet or RS-232 bridge device to communicate with the KNX bus as a subsystem of a more complete automation project using Control4 or Crestron. These days, most of the major U.S.-based home control manufacturers offer KNX bridges.

Every European home automation system that I have encountered uses KNX as its core technology. There’s no escaping it.

Old-School Software, Misplaced ‘Popularity’

KNX installations are set up and programmed (Europeans always use the word “commissioned”) using ETS, a software application that runs on Windows only. It is expensive and only available from the KNX Association.

ETS and ETS training are a major source of operating income for the KNX Association. You pretty much need to have their training since the software is counterintuitive (old-school Windows app) and there is little in the way of alternative or competitive training available. I taught myself how to use it mostly from trial and error.

You might get the idea from the popularity of KNX in this part of the world, that home and building automation is widely used. However, the popularity of KNX is not exactly what it seems.

I would estimate that 80% of all commercial and 99% of all residential KNX installations I have encountered – we are usually called in to get them working correctly—are not used to automate anything. KNX simply is taking the place of conventional electrical wiring.

CE Pro @ CEDIA Expo 2015: News, Products, Technology, Opinions, More

There is a myth that KNX is somehow “high tech” and a home or office with KNX lighting makes the dwelling a “smart home” or “smart office”. Developers install it in high-end high-rise residential buildings to promote their projects as “smart” (gee, this never happens in the U.S.).

In reality, KNX devices are simply programmed to do the same things they would with conventional electrical wiring. There might be a few three-way switch set-ups and a switch by the entry door that turns off all the lights.

Admittedly, this is not the fault of the technology itself, but a poor understanding by builders, contractors and consumers of what the technology can do. Despite all the hype, home owners over here have no understanding of what home automation is about, and dealers have done a dismal job of explaining it.

Furthermore, due to the language barriers throughout the EMEA, training for these constituents is very limited.

Prospects for KNX in the U.S.

So can KNX adapt to a different automation model in the U.S.?

The question is really: Can it compete with other technologies in the U.S. that do the same thing and more?

If it can position itself as a standardized lighting control system, it may have a chance in that niche since there are so many competing, non-standardized lighting control technologies.

Look at the example of Savant abandoning its LiteTouch hardwired lighting-control system. Existing customers will have to update their entire system – from dimming panels to every last light switch – when any part of the system fails or falls out of favor.

In the case of KNX, they could get away with simply swapping out the central controller. That’s a pretty big deal

However, KNX has many problems for custom installation companies like mine, and you should be aware of them. Admittedly, some of these are my personal opinions, but opinions formed from decades of experience with “standards”.

1. While it is a standard, KNX covers only a part of product implementation. Manufacturers are free to add proprietary functions and features to their products, and since KNX devices are quite commodity in nature, manufacturers rely heavily on variables that send/receive from only their products – much like many manufacturers do with their own “flavors” of ZigBee.

The manufacturers of KNX components are big old companies. Try to find out from Siemens what the heck some proprietary variable is in one of their products. Only Siemens authorized dealers have that info. Yes, the data sheets are on the Internet, but a lot was apparently lost in translation.

2. Seems like standards always come with trade associations to “milk” the technology, and KNX is no exception. It is simply called the KNX Association. It bills itself as “the creator and owner of the KNX technology”. Not sure what they mean by “owner” of the technology but they seem to keep pretty tight control over all things KNX.

I really don’t appreciate another trade association that claims to promote a technology as “open” while at the same time claims to “own it” and keeps a lock down on the tools and training needed to promote it. Been there, hate it. If it is actually open then I should be able to purchase the software tools from several competing companies and get my training on YouTube if I feel like it.

3. Custom building wiring that locks the owner into one system is a bad idea. I can speak with some authority on this topic since I once created a company that required non-standard wiring for our home automation system. Been there, regret that.

Once a home or building is wired for KNX (daisy-chained switches on a 4-wire low-voltage bus with a single run back to the panel), the owner is pretty much stuck with it forever. A building wired for KNX can’t change without a major remodel. True, this might be the case with other proprietary hardwired systems, as well.

In our work, we only use lighting or electrical device control technology that builds on conventional building wiring, such as Control4’s ZigBee-based lighting or else PLC (powerline control) products. The system can always be converted back to conventional control.

4. My biggest headache with KNX is the project software. The configuration file for a project—device setup, addressing and binding—is not stored anywhere in the network. This is true of a lot of technologies. It resides on a laptop somewhere that was used to commission the system with ETS.

When I have to take over a home or office project that uses KNX, I got a big problem. ETS can print out a copy of the configuration and you MIGHT think the installation company would keep that on the site. You would be wrong of course (customer service in the “ME” is a luxury). I can use ETS to “sniff” the KNX data traffic and try to figure out what’s up when I flip a lighting switch, but this takes forever, and I still won’t know what parts of the network I’m missing.

This challenge, of course, is not unique to KNX. Proprietary control systems might lock up project data in a dealer-owned vault; however, KNX isn’t supposed to be proprietary.

5. There is also a myth over here (and I am not sure where this comes from) that KNX products are cheap. They are not, relative to similar technology. So far, few KNX products are made in China. The lighting control part of an automation project will actually cost about the same as using a Control4 wireless lighting control system (a lot due to cable and installation time). But since customers here have heard about KNX, it will usually win the project.

I was a big believer in standards. Goodness knows I spent enough years helping to develop them. But I lost my appetite for ‘em long ago. Somebody else’s idea of what you should do. The only standard I have really come to appreciate is Ethernet. It had a humble beginning and slowly grew by truly being OPEN. It works amazingly well and is now dirt cheap. Best of all, nobody owns it.

Will KNX Home Automation Standard Make it in the U.S.?
CEDIA 2015: KNX to Push Dominant European Home Automation Standard in the U.S.

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Posted by Jean-Pierre Joubert on September 25, 2015


I hear you. Some of this will be cultural issues, but when things are questioned, and particularly when there are misunderstandings or inaccurate information presented, people seem to react this way rather than reacting from a position of openly exchanging information in order to help educate and correct. When livelihoods and ethos are involved, or questioned, it becomes more heated.

in this case I can see how the title itself, and a number of issues noted due to misunderstanding, could put those in the KNX camp on the defensive. If a discussion had started with the title, “Step away from the <add system here>,” I imagine you would see similarly-heated responses from those who have a positive and extensive history with said system, whether it be Lutron, Crestron, AMX, etc.

That said, I do see this type of reaction as not dissimilar to the “fanboy,” reaction that you see in discussions about Apple on computer forums. Flamewars abound on the internet as a result of opinion, emotion and anonymity. It’s best to rather ignore those comments and concentrate on the others. Not always easy, but still best practice.

Rather step away from the flamewar ... wink

Posted by Julie Jacobson on September 25, 2015

It really bothers me that some people in the KNX camp are so hostile and defensive towards Grayson.

This is what KNX is up against in the U.S. This is what you should be prepared to hear from all dealers and manufacturers.

Grayson opened up some great dialog about KNX in advance of CEDIA, and the KNX camp should be thrilled.

Posted by Audioplus on September 25, 2015

You should continue doubting yourself as being rude, but I believe your apology is accepted by a multitude of Professional Integrators. If KNX is just beginning to market in the US, this has been a good article to start off with. CEDIA should become an interesting launch pad. After all, architectural audio applications is a totally different world in your market compared to ours here in the US.

Posted by Julio de la Orden on September 24, 2015

I forgot to say something more.

This gut says:

” There needs to be several OPEN SOURCE software tools for this system “

What ??? !!!

Please, tell me what ” open source ” software is available for any of the big US home automations systems ... ZERO !

They are ALL propietary and obscure systems, that blocks any developer to access to they API / SDK to avoid third parties doing more things they are doing on they own. Some of them even limited the screen resolution of the GUI project if you are not using they own touch panels, that simply cost 10 times more than an iPad.

Just Google KNX software tools and you will discover a few dozen developers who offer alternatives and / or complements to the ETS software tool, from universtity studends to big corporations, who offers they software form free or for a very reasonable license fee.

Do you remember a few years ago when a end user, very clever and IT capable guy, integrated HTML-5 App with one of the most famous US control systems he had at his home?

It toke just 24h to delete the source code of this software from the internet and block this ” free ” tool. Is this an example of you do understand ” open source ” ?

If I order an US control system solution from an idiot, I will get a shit of home automation, the same applies to KNX or anything else available in the market, so when you say that you are serving ( BTW, I don´t believe it ) KNX systems that were poor and defective, I can say the same about me serving many US type of control system that have been done by similar idiots, and that does not mean that the system it self is not good or not reliable.

One big difference between KNX and the US solutions is training, here in Europe most of the electrical / industrial engineers get high level of KNX training at the university as part of they degree ( or as an option ), that means that this engineers ( after 6 years of learning ) can later develop projects and or supervise the installers.

In the US, any person, independently of his tech level, can go to a two day training and get certified by the manufacturer.

The same applies to other ” certifications ” like CEDIA, HAA, THX, ISF, etc, all of them are for non-real tech people, to make regular people confident about they non-knowledge and let them go to the market to do some business for the big companies.

Of course there are exceptions, but this is a good picture of the situation.

Posted by Thanassis Kanellias on September 24, 2015

At last! Just as I started to doubt myself and think that I was a rude and mean in my comment (comment #7). At last, after 26 comments, a real professional that answers properly to the unspeakable author of this article. At last someone else besides me that comments the motives behind this article and the TOTALLY untruth arguments. Thank you Julio! It was hard to believe that there were so many amateurs and hobbyists commenting so far in this ridiculous article. I thought that the “Pro” in CEPro means professional.

Posted by Julio de la Orden on September 24, 2015


What a list of stupid arguments about KNX, I am really surprised that some one that clearly as no idea about KNX ( he admits that ) is writing an article on this site and having so much publicity ! Who is going to call him for on site service and support ? ja, ja, ja, simply this is not true !!! This guy is a story teller !!!

Who is in the shadow beind this article ? Maybe one or two US home automation manufacturers that are scary about KNX comming to the US ? and of course want to scare the dealers and installers.

I am sorry to say this, but after working with the best / biggest US home automation companies for 21 years and having done hundreds of real big projects, I must admit that KNX is a very good product / standard, reliable and that covers many things / needs that we have in the projects, both residential and commercial.

End users will love it, why ? very simple, because the KNX keypads, there are so many choices, that any shape, color, design, quality, function, ... is available, and remember, the end user only sees the keypads and the functionality, and about what ever is in the background, they really don´t care.

Today, once we decided to mix some Top US home automation products with KNX, we do more and better projects than before, with a 50% growth this year, customers just love it, and we two, because zero post sales problems means less on site assitance and more margin.

Of course I will not use KNX to control AV equipment ( not yet ... ) or to program complicated logics, but for HVAC two way control, light control, motorized devices, etc, no doubt, it works great.

Regarding HVAC, it works 100 times better than any other control protocol or system, specially if there is a mix of air conditioning and floor heating. The logical processing included inside the devices is so powerfull and welldone, that it takes a few minutes to configure and set up.

In the comming months ( or weeks ) you will see many new products in KNX that covers home automation and system integration needs that can not be done with US type of solutions / brands, specially in the multi room audio department ...

What about swimming pool control ? KNX offers the best solution on the market, to make a real inteligent swimming pool, something that non US type of control system can even dream about to do.

Regarding that US companies do have gateways to KNX is true, they are using gateways made by European KNX manufacturers ..., that are just KNX to IP gateways. The same applies to ModBUS, BacNET, Lon, etc. Some of them have been mentioned here in before.

Big projects ? No problem with KNX, you can control many thousends of devices in real time on the same IP network using a KNX server platform ( software solution ).

My recomendation, you better start learning KNX shooner than later, it will hit the US very soon and for sure it will become a big player in the market. Here, in Europe, they already have 80% of market share, probably more at the of 2.015, that means it is the facto standard in EMEA, with over 400 companies behind it, some of them very very BIG ( Siemens, Scheneider, JUNG, ABB, ... ).

And learning KNX on a basic level is much easier than learning any other control protocol or standard, in 3/4 days you can start doing some mid size project with usual average type of functions.

We get many request from the US about doing KNX projects there, this means the customers are asking about it, the home builders want to offer it, and all this are warning signals for everybody, just take note ...

BTW, you can develop incredible GUI projects that can run on iOS, Android, MS Windows and Mac OSX, that works with KNX and ANY of the other control systems that are in the market ( residential, commercial or industrial ).

Posted by Todd Nelson on September 24, 2015

I only used Lutron as an example of great tech support. Lutron, until recently, has just been a lighting company that I would not use to integrate multiple platforms. I would use RTI, Crestron, URC, Control-4, or a host of other companies that all have better tech support than KNX. KNX might be okay for new construction, but would be extremely cost prohibitive for remodel due to its’ being hardwired. Another drawback is the extra 2 wire that has to be run in new construction as a daisy chain. With all the other structured wiring that is done now, Cat 6, alarm wiring, coax, and some fiber, a dealer for KNX would have to do some serious selling to convince an American client to spend the extra money for a system that is geared toward European companies and standards, and has lousy tech support.

Posted by Jean-Pierre Joubert on September 22, 2015


I’m not sure I follow your thought process, namely why you state that anyone is asking, “the U.S. market to backwards,” why you state that the tech, “has already failed miserably,” and why you equate KNX to an 80’s PLC.

The protocol has been around first as EIB, and now KNX, for 25 years. In that time I’ve personally seen it grow from a little over 100 member companies, making products for it, to well over 300 manufacturers and over 7000 products. (I think it’s much more than that now, but I’ve been out of the loop for a few months.) If that’s what failing miserably looks like, we could all do with some of that kind of, “failure.” wink

You ask what it brings to the table that hasn’t been in the market, or more specifically in comparison with Lutron? Standardization, a vast amount of vendor selection, and an open system (which can be argued depending on your definition of, “open”).

It’s also product and vendor agnostic, so KNX does not, “tout,” one over the other. You can happily use Lutron blinds if you want, or Somfy, or whomever else’s motors you want. (Btw, comparing Lutron to KNX is a moot comparison given that Lutron is a KNX Member/manufacturer, as are AMX, Crestron, Elan, and Control4. You can happily interface Lutron lighting and blinds with a KNX control system if you want.)

But, as you bridged the topic, let me ask you this: How would you use Lutron to integrate and control a 24 Zone Mitsubishi VRV HVAC system in a commercial building using Lutron?

I know that I can use one single KNX device to do that easily using an dedicated Intesis Mitsubishi gateway. One device. And, with the exception of adding Group Addresses and some network settings, it’s plug-‘n-play.

However, if I don’t like their product, I can go any buy a similar unit from CoolBridge. Both work with the same system and, if one company goes out of business or I simply don’t like them, I have options while still using the same bus system, saving time/money by not having to relearn everything from scratch. (Can you do that with Lutron?)

This, by extension, adds longevity to any install. God-forbid something happens to Lutron, but given that situation, what would happen to your system if some component failed? Are you going to cobble together a solution? Or are you going to rip out the system and install something else entirely? What would that cost?

With KNX, if a vendor goes the way of the buffalo, I just turn to another vendor. The system stays the same. Did my GIRA 16-channel Switching/Blind actuator just die? No problem. Drop in an MDT unit instead. Or a Zennio. Or an ABB. Did the dedicated Jung touchscreen on my wall just die? Or does it not do something that I want it to? Get a Zennio. Or an Eelectron. Or ... you get the point: Vendor agnostic means the same system, the same software, but multiple avenues (and price points!) to the same solution.

I dislike Kool-Aid as much as the next guy, probably more, but you seem to have some grave misconceptions that are based on opinion rather than researched fact. Some resources for you, then, to help clarify things ...

Free software is here:

Free Training is here:

A (constantly growing) list of manufacturers is here:

A list of applications for KNX:

I would urge you to have an open and honest look for yourself. Download the software. Have a look through their online tutorials. Read their articles. Learn about it. Everything is free to check out. If you still don’t like it after that, fair enough. That’s your prerogative. But at least you will have come to your decision based on research and experience rather than what seems to be hearsay and conjecture.

KNX isn’t the best thing since sliced bread, and there are issues that are being addressed, but what it is is a really good solution for ensuring system longevity, inter-operability of components and functions, and standardized integration between a vast number of manufacturers, products and systems/sub-systems.

Posted by Steven Brawner on September 22, 2015

So, just to be clear, someone wants the U.S. market to go backwards by using technology that has already failed miserably.  How about I pose a few easy question for everyone to ponder.  What does KNX bring to he table that we don’t already have spread throughout our market?  What does it do that Lutron hasn’t been doing for 15+ years?  The system is mostly lighting and motor loads, but almost every control system i can think of does that plus audio/video control and IP feedback integration.  I understand that most of the world is way behind the U.S. on automation and entertainment, but in what strange world would I ever want to go back to using the equivilent of a 1980’s industrial PLC (programmable logic controller) to integrate my advanced automation system?  i look forward to hearing the sales pitch at CEDIA, should be interesting since i have done extensve PLC programming and I have a propensity to dislike Kool-aid. 

In my opinion, when you are touting Somfy motors you obviously dont understand what true excellence in integration is.  I prefer for my neighbors not to hear my blinds moving.  Stay silent my friends, go Lutron.

Posted by Jean-Pierre Joubert on September 21, 2015

Grayson: Thanks very much. Appreciate it. Sorry about it being wordy. I’m a bit too verbose when I’m excited about something. Hehe.

Re: control, I completely agree even if it’s part of another system. I prefer that it’s the main system, but as you say, a lot of what you want is personal preference due to experience and differing ways of working.

Re: your first reply, I can empathize. I’ve also had that sort of experience at times. Not always, but a lot of that comes down to people who want, “automation,” to, “keep up with the Joneses.” Those clients are, frankly, frustrating as they’re not using it as it was intended and it makes for boring work for us. Work is work, and if it pays the bills, great, but I’d prefer to be challenged and do something, “fun,” as well.

Re: your second comment about programming problems, this is, in my view, a fault with us as Tutors as well as a fault with the, “official,” Training Centre curriculum.

On the curriculum side, long story short, there’s an official curriculum we have to cover on the Theory side of things, but nothing on the Practical. With the exception of a lopsided focus on the ETS software platform, we have to develop our own. As a result, how much people learn regarding practical application and actually programming an install is not standardized.

It’s sounds like a pride-filled statement, though I really don’t mean it to be, but the issues I’ve had to fix were generally done by people I didn’t train. For me, I learned as you did, practically, so I don’t care as much for the theory as the practical. You can know everything you want, but if you can’t execute in an functional way, you really do need to learn more, especially if it involves any sort of automation rather than simple control. Elegance comes later, though hopefully not much later.

Again, I don’t peg this as a student being lazy or poor; It’s a fault of the Tutor’s personal practical curriculum teaching them how to pass the exam rather than perform their daily work. This is not always the case, but it depends largely on the experience of the Tutor. Some, like me, have been in the trenches and are able to give advice on what caveats there are and what alternate angles to keep in mind. Others have focused on the theory and, in my opinion, the training they can offer is the poorer for it, unfortunately. It’s the old, “college vs. university,” argument, really. Both are valid approaches but, if you’re in the field, I want someone with me who can walk the talk.

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Posted by Abdulrahman hourani on September 16, 2015

It’s very nice automation particularly in villas. We excited many of it in Damascus (Yaafour . resort) .
It’s easy installation
Save cables and Effort
Sophisticated switch and panel
Many advantages. on.

Posted by Robert Heiblim on September 16, 2015

I also know and respect Grayson from the CEBus days. He is knowledgeable on these subjects to the nth degree, and being modest in his comments. This standard was based and developed from a very different marketplace, and I agree it is not the way forward for the US. Thanks Grayson and CEPro.

Posted by Frank White on September 16, 2015

Wow, Greyson, what a mouthful…hope no shady trench-coated visitors come see you late in the evening!

Really miss seeing you and having your great perspectives on a regular bases.

Hoping the best for you over there. -f

Posted by nick on September 16, 2015

I agree with a lot of your comments, but disagree with some of them.
Spot on about ETS being old time windows type software, difficult to learn to do more sophisticated programming.
Also true that KNX might be a standard, but some manufacturers include some good functionality, some don’t. You really need to know and test what products you will be using. You can create a really cheap KNX system, but it wont do much. A KNX system with really good selection of products can compete with the best US systems out there, but no it wont be cheap.

However from my experience the following are not true:
1. Wire with KNX and you’re stuck with it. Not true as its a bus system, and most bus systems are wired in a similar fashion, whether you have a processor or not. With some clever design you are covered with most systems (I’ve done it with Lutron, Crestron, Control4 and KNX)
2. KNX devices are simply programmed to do the same things they would with conventional electrical wiring. Not true at all! A good ETS programmer can program (or commission) a system to do any function that processor based systems can do! True however that its mostly for lights, motors and HVAC, not able to control AV. But as you said you can easily connect it to Crestron or others.

I do prefer US type systems with processors myself, but I cannot agree that KNX is not a powerful and reliable system. One of the reasons they are very popular in the EU is that it is very easy for consultants to specify without being affiliated to specific brands.

Posted by Julie Jacobson on September 16, 2015

Ah, so good to have Grayson back. I bumped into him on a bus in Amsterdam about 5 years ago.

Posted by Dan Christians on September 16, 2015

Very informative and timely article, appreciate Grayson’s insight!

Posted by Thanassis Kanellias on September 17, 2015

It is a shame that you publish things like that and that you have them headlined. Totally untrue article, full of mistakes from someone who obviously knows automation like a farmer know astrophysics. CE pro, you follow the scotadistic trail of depreciating any non-US technology in favour of US systems that cannot even compare to KNX, why? I thought you existed to inform not to manipulate and do politics… Not able to control AV? Are you serious? Tens of products. Please get informed!

Posted by Phill Provis on September 17, 2015

Fantastic and balanced article, KNX is clearly unfounded “open protocol” marketing hype in an attempt to promote and suatain legacy technology in an ethernet world.

Posted by Dennis W Erskine on September 17, 2015

This is a closed proprietary “standard”. We don’t need YACS (yet another closed standard). An open standard (as recognized by ITU or ISO) would be more appropriate. Oh, and 8-bit analog is so 1960’s. Sounds like a fun project….

Posted by Jean-Pierre Joubert on September 17, 2015

Thanks for the article. Having just moved back to Canada recently, and being a KNX Tutor in South Africa for a number of years, I was chatting with some colleagues the other day about KNX and one of them forwarded a link to your article.

1. You mention that the data is only 1-bit (for on/off states) and 8-bit (for analog). That’s a mixed back. In practice, if you’re talking about lights and blinds, yes, that’s practically what is used. However, those are not the only data-types available by a long shot, nor are lighting and shades remotely the only things used/done with KNX (More on this later).

2. You mention the TP (Twisted-Pair) bus as a, “4-wire bus,” which isn’t true ... something you quantify a little later but for simplicity’s sake/to reiterate: It’s a 2-wire bus, (hence twisted-“pair”) where the data and power are multiplexed together onto the same pair of wires. The other two are only for additional power to certain specific devices that require it (i.e. touchscreens for the most part). And it is possible to get cable without the additional pair of wires, though I really don’t see the point if, “future-proofing,” (hate that term!) is in the cards at all.

3. You mention not having seen RF, IP or Powerline equipment being used. On the whole I’d say that’s pretty true in Africa, at least in the installs we were a part of, at least on the RF/Powerline side. Powerline is dead. Nobody really seems to use it in Europe. RF is too expensive per-device and device functionalities are simple and limited, which made it’s use in Africa (and I’d argue anywhere else) extremely cost-prohibitive. It’s sold as great for retrofit, but practically those jobs can be done just as well with Zigbee, Z-Wave and EnOcean.

IP, on the other hand, is used quite a bit in installations, but its main application is in increasing information bandwidth capabilities on the back-end. On a Residential side, there’s limited use/application for it beyond adding some sort of network controller (i.e. GIRA’s HomeServer, Bab-Tec’s eibPort or a Weinzierl BAOS coupled with something like Houseinhand). The building is just not large enough to warrant requiring the speed benefits of using an IP infrastructure (The only time I’ve seen TP fall down is when controllers are brought on-line after a power failure, and read flags are incorrectly set up, so even there IP can have limited benefit).

In a larger commercial infrastructure, I would recommend at least looking at using IP for the backbone. We did this with a automated shade system in one building in order to both handle the large amounts of blinds, the control via the particular shading controller that was specified by Somfy, and integration with a Crestron controller. It doesn’t always make sense, but it can help depending on the amount of devices per floor.

4. You mention that lights are connected to 220V ... This is me nitpicking, to be sure, as I’m sure you’re aware of this but for the sake of those unaware there are DALI gateways, DSI controllers, 0-10V fluorescent dimmers, DMX, and there are dedicated LED dimmers. (Including even things like Philips HUE controllers) So, 220V is only for conventional/halogen loads, and you are definitely not limited in what you’re controlling there.

5. HVAC control is pretty simple, actually. Granted it depends on how you go about it, but if you’re connecting using any of Intesis or Zennio’s interfaces, it’s a cinch! Intesis is especially good at this, with dedicated interfaces for various specific HVAC systems like Daikin, as well as generic controllers for BACnet, LON, etc. Plus, if you have to use LON and you’re not a LON-house, their LON interface doesn’t even require learning about bindings, SNVT’s, etc.

Now, if you’re trying to control an individual chiller plant, or a bunch of those, then I’d say you’ve definitely got a point as I hated working with those units.

6. You mention that their software is Windows-only, overpriced, and that the training is required. I had to learn the same way you did, trial and error, and the hardest part for me (not having an electrical background, but rather an IT one) was understanding electrics, not the software. A lot of my students who came from an electrical background, however, had difficulty understanding the software simply because of a lack of IT training. Those with more of an IT background didn’t have trouble picking it up but, then, they did have a tutor who had been using it for years to help them, which is not something that either you or I had.

Their software is definitely overpriced for what it is, I found support extremely frustrating to obtain in a timely manner (the odd time I needed it), and limiting it to Windows in this day and age is pretty ludicrous IMHO.

7. You mention that, for the most part, the installs simply replace conventional wiring with KNX. I would agree with this, but as you mention it is less the integrator’s fault and more a lack of understanding. To be fair to builders/consultants/owners, though, I’ve seen some pretty horrendous installs that we were called in to fix and, if that is what the consultants’/builders’ first experiences are with, “automation,” then I can appreciate them not wanting to do more than the bare minimum.

I’ve had the pleasure of working on many wonderfully automated installs, interlinking HVAC, heat exchange systems, solar heating, geysers (hot water heaters), and pumps, but those jobs were few and far between.

8. You mention that the manufacturers are big, old companies that are a pain to work with. I have found that with some companies, but frankly with over 300+ manufacturers, this all comes down to who you’re working with. I’ve had the pleasure of working with many smaller outfits like Lingg & Janke, Intesis, Weinzierl, B+B, Bab-Tec, and MDT, among others. I had the privilege of beta-testing the new switching/blind actuators from IPAS late last year, which I am convinced are game-changers as far as cost and functionality are concerned. (Plus, on last chat with them, they will work with 110VAC, something that few KNX products can do at present.) Like anything, if you’re willing to stray off the beaten path, you will sometimes be disappointed and, at others, greatly rewarded. These companies I can most certainly say fall into the latter category, particularly when compared to some of the larger giants. (Who, frankly, do have some nice products, too!)

9. You mention KNX having a double-standard, which I can see from one perspective. My only thought really is, “How do they maintain it as a standard, and standardize the tools, if they open that side of it up?” It’s something that can be discussed ad-nausea, but I don’t have a fully-formed solution to it so I’ll leave this there. It is something that does warrant discussion, though whether or not it will be listened to is another kettle of fish entirely. It’s a question of, “how open is, ‘open’?”

10. You mention being locked in due to the wiring, and again this I can fully agree with as a concern. As you know KNX has been around in some form for over 20 years, so one would hope that it will be around for many more and that this would not be an issue. With many, many vendors for most components, I would say that while you are locked into an infrastructure/protocol, you are not locked into a particular vendor, something which you point out above in your discussion re: Savant ditching one line of their products. This all comes down to how you, as a person and a company, want to deal with things. For me, having worked with KNX for 10 years, I’m fine with it. For you, it seems, not so much. Different strokes, I suppose.

11. You mention the configuration data not being on the network. Having had to re-engineer a couple installs over the years, I can see this is an issue. I can see that they are trying to address this via both their built-in Network Storage check-in/checkout feature for ETS4, and
with the new, “Apps,” that they’ve allowed in ... there’s a nice-looking one that addresses just this and will sniff the packets for you, and rebuild the building from the data on the network, but that’s not native and is a slight extra cost. But I do hear you and can see how that can be a pain, especially with larger jobs.

Where I do have issues on that side of things is for those components whose data is not contained within ETS. That is an absolute pain if you lose the file, and practically ruins the ETS idea of, “One Program to Rule Them All.” That I dislike to no end, and there is a lot of this among many manufacturers products, unfortunately.

12. You discuss Chinese products and price. Here I’m with you. Part of this, I think, comes down to R&D costs, part of this to licensing/certification costs, and part comes down to the market itself. I had thought, with Chinese products, we would see pricing drop to where it should, in my estimation, be. This has come down a bit, and here again many of the smaller manufacturers are doing great work trying to make things cheaper and cheaper while increasing functionality (Moore’s Law being what it is), but it isn’t happening as quickly as many of us would like. Instead the Chinese products seem to have been released at a slight decrease in price, while not really offering anything functionality-wise that makes me jump for joy with interest. I mentioned the IPAS switching/blind actuators above, and frankly I think they will be a company to watch in the coming years as they are making strides towards reducing the product cost for installs. But, again, if you can get an extra 100 Euros for sticking a stamp on your box, it seems many manufacturers are content to do this and not, “rock the financial boat,” of the industry too much. Sad, but true.

13. You mention Ethernet as the only truly open standard, and here I think you are definitely on to something. Interestingly I had a chat with another KNX Tutor friend last year about this and he mentioned part of the hindrance for IP-based KNX products is the additional power required to make it work. The guesstimate-rule for KNX device power consumption is 10mA for a TP device. He mentioned that with Ethernet it jumps to something like 10 times that figure. From a power consumption standpoint, then it does make sense to keep as many devices on the TP side of things rather than the Ethernet side. But, I do agree it is something that should be addressed by the manufacturers.

Again, thank you for the article. I enjoyed reading through it and thinking about KNX again. I am hopeful there is change on the horizon to make KNX a better system, but there are certainly issues which need to be addressed in order to make it viable to the North American market, 110VAC and local certifications included.

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