Bus systems - wiring, planning, etc.?

Hello everyone, some of you know that I am new here and am slowly approaching the relevant topics. As a very tech-savvy person, I am very interested in the topic of automation. I am currently surprised that the trend of advice for new buildings is to connect everything via bus cables. An enormous planning effort with a very high likelihood of retrofitting over the next 30 years. A radio solution or a powerline solution would actually be technically possible without problems, requiring much less planning and hardly any additional work for the electrician. Every component to be controlled is powered anyway. Thus, every component could also be addressed via this normal power cable. And if someone wants to save a little when building, they simply retrofit certain components such as lighting at a later date and operate them manually in the meantime. There are no additional costs for the non-smart installation of a lamp anyway. Or is this already the case and I have misunderstood the recommendations for implementing the bus system at KNX and similar? Best regards Matthias

Oh how naive and innocent... please don't take it the wrong way. It just means you would have to delve much deeper into the topic.

As long as bus systems are not offered by the standard electrician, builders with conventional electrical installations will be more or less "shortchanged." Those who want more need more money and a capable electrician.

However, I am of the opinion that one can also live with a radio-based solution with decentralized switching actuators, for example in (deep) flush-mounted boxes.

Okay, I will continue reading up, but what I have read so far was: - there are wireless solutions - there are powerline solutions - it is said that powerline solutions are slower - it is said that powerline solutions are less reliable or simply "worse"

Technically, I can't quite understand it. A powerline system in IT achieves real 300 Mbit/s or sometimes more. However, I would say that apart from sensors like rain sensors, wind sensors, etc., no permanent communication consumes bandwidth. Window opening can be monitored as a state and does not require permanent communication. So why should powerline be so slow or so bad in home automation?

Basically, in IT there is also the logic that LAN cables are better than WLAN. In reality, I operate a pure WLAN with almost 15 end devices and never reach the limits of the overall system. Only direct communication can sometimes drop to 5 MByte/s (not bit). And that is due to the components, not the network. Even that should be enough. Technically, it should work flawlessly with both. Only with WLAN would I see the increased power consumption, because the connection is usually maintained and consumes more than via cable.

So why the tendency towards the cumbersome and poorly improvable cable solution?

But let's start from the beginning:

So why the tendency towards a complicated and hard-to-improve cable solution?

Why the mistaken assumption?

I’m currently surprised that the tendency of advice for new builds is to connect everything via bus cable.

Well, people usually want peace of mind for several decades when investing in something like a house. The lights should turn on when you press the button or enter the room, and the rest of the technology should work invisibly in the background. And that also in 10/20/30 years. You can achieve that relatively easily with KNX. Other approaches have their difficulties. The past simply shows us that and we should learn from it.

An enormous planning effort with a very high likelihood of retrofitting over the next 30 years.

You should put in the planning effort. Before buying a new TV or lawnmower, tests are read and technical data compared. Strangely, it looks quite different with electrical installations. There it often goes like this: “One electrician, please.” Especially nowadays with the possibilities, you should engage with it. And that beyond the level of simple series wiring and sockets with timer function. Regarding the likelihood of retrofitting, you are on the wrong track. RS-485 is currently experiencing its second spring.

Just as info: it dates from 1979!

And for example KNX is not asleep. Everything that proves itself will sooner or later be integrated.

A radio solution or a powerline solution would actually be technically easy to implement,

Yes, sure, but they often come with considerable limitations in terms of communication and stability compared to a wired variant. But powerline and radio also work with KNX.

requires much less planning and hardly any additional work for the electrician.

But only if the electrical system is to be as simple as in grandpa’s time. With some light if-then tasks like a bit of automation regarding lighting, sockets, and shading. Everything else then requires a different approach. Or rather, more planning and additional work.

Every component to be controlled is powered anyway.

Misconception. Or rather, in a smart home it is especially important to minimize standby consumption. So ideally every component to be controlled is only powered as long as necessary.

And anyone wanting to save a little when building, retrofits certain components like lighting later and operates them manually until then.

There is a mistake in thinking here. You must then save somewhere else. Otherwise, you are left only with radio and retrofit. Why would you want to restrict yourself? Especially with lighting, you can do a lot wrong if you follow a set pattern.

There are no additional costs with the non-smart installation of a lamp.

Of course, if it remains only one light point. With a radio receiver, however, the lamp remains non-smart; in 90% of cases, you only get the possibility of remote control. It only becomes smart when everything works together and not just isolated lamps are switch-/dimmable.

- there are radio solutions
- there are powerline solutions

Yes, and you can have all of them under the KNX umbrella.

KNX currently offers 4 types of communication (bidirectional and integrated):

KNX-TP (Twisted Pair)
KNX-PL (Powerline)
KNX-RF (Radio)
KNX-IP (Ethernet/IP)

More communication types will follow. Via gateways, KNX commands also control/use manufacturer-specific and other media, communication standards, and protocols. For example WLAN, Enocean, ZigBee, Z-Wave, Bluetooth, DMX, RS-485, etc.

- it is said that powerline solutions are slower
- it is said that powerline solutions are less reliable or just "less good"

Yes, they usually are. There is often the “thinking second”; that is why most PL solutions have more or less failed. Well, and they are typically not cheaper than KNX.

So why should powerline be slow or bad in home automation?

Price, speed, possibilities, installation situations, reliability. There are many reasons why powerline is suitable for IT, for example, but only to a limited extent for building automation and above a certain size (number of participants), other solutions are simply better.

Only with WLAN would I see increased power consumption because the connection is usually maintained and consumes more than via cable.

Yes, I already mentioned that further above. Power consumption is one of the reasons why TP is simply better. With 15 participants, you might still overlook that; but how about with 100 or 200 participants?

Okay, sure, if everything is directly wired, then I definitely see the advantages. Ultimately always the most stable and energy-efficient method.

For understanding:
Powerline is a principle and KNX is a manufacturer. Or is Powerline a proprietary system from D-Link?
At least I meant the implementation using the existing power grid, not a solution from D-Link. Thus, the quality of the implementation would be independent of the Powerline operating principle. Because Powerline itself, if well implemented, should be just as good and fast as TP. Or at least in the maximum millisecond range.

When I think about lighting, I just assume that automation needs two components: lamp and sensor. Both are powered. So both are connected to the power grid. Thus, there already exists a cable that connects both with each other and with the control unit/the server. So one could just install a normal lamp during construction, then later install a Powerline sensor and a Powerline lamp connection/socket (for example from KNX) and then define via software where both are located.
Basically as if the Powerline electronics were simply in the wall socket (the hardware). It does not matter which end device is plugged in because you switch the power of the socket on or off. For a lamp and many other consumers actually a simple, binary principle. And for a lamp, roughly simplified, not much more complicated than a classic motion detector. The motion detector detects movement and then switches on the built-in lamp. With automation it would be exactly the same, only the lamp is not built in and therefore a simple signal to the server is needed, which switches the "socket" on and that’s it.

Of course, this is complex in terms of programming. But purely from the hardware side, these applications are rather easy to implement. And that via Powerline.
I can’t think of an example now that would be complex in communication. In the sensors, yes, but in the message to the server and then to the actuator, actually no.
Just as an example: a thermostat can be complex. But actually it is a simple temperature sensor (e.g. bimetal) that then signals whether to turn on or off. That is, motor running left or right. This requires almost no bandwidth in communication. And millisecond-range times are also easily sufficient here.

And a power grid itself is also more stable than a TP cable. The wires are significantly thicker, there are fewer damage points.

As I said, I wonder if the technology is the problem, or if here they are trying to sell more complex solutions because they simply generate more money. Installing an additional cable finally costs a lot more than just replacing the fuse box with a control unit.
This is not an accusation, I am just wondering why this more complicated and expensive way is chosen with such an elegant and universal solution like Powerline (with such low required bandwidth).