ᐅ Bus systems – wiring, planning, and more?

AleXSR700 schrieb:

Powerline is a concept, and KNX is a manufacturer.

No, you are quite mistaken. Powerline is a communication medium, and KNX is certainly not a manufacturer.

KNX is a communication standard for building automation.

It is supported by over 450 manufacturers who have their products certified and are then allowed to sell them under the KNX label.

Ah, okay, I’m really sorry about that! That explains a lot.

Then the question should actually be:
Why is everyone moving away from the communication medium Powerline when, for the reasons mentioned, it would still be the most universal, elegant, and least complex method?

AleXSR700 schrieb:

Ah, okay, I’m really sorry! That explains a lot.

You don’t need to apologize, but that probably explains my initial reaction.

AleXSR700 schrieb:

Why is everyone turning away from the communication medium Powerline when, for the reasons mentioned, it would be the most universal, elegant, and least complex method?

Because the Powerline approach simply isn’t that. It is actually quite complex, far from elegant or universal, and also more expensive, among other downsides.

AleXSR700 schrieb:

I was referring at least to implementation via the existing electrical wiring, not a solution from D-Link. Therefore, the quality of the implementation would be independent of the Powerline principle itself.

No, data transmission through the electrical network existed long before D-Link was founded in Taiwan.

AleXSR700 schrieb:

Because Powerline itself, if implemented well, should be just as good and fast as twisted pair (TP). Or at least have delays within the low millisecond range.

That’s exactly the problem. Even delays in the millisecond range are enough to relegate a system to a niche role.

AleXSR700 schrieb:

Regarding lighting, I think that automation requires two components: the lamp and the sensor. Both are powered from the electrical network. So, a cable already exists connecting both with the control unit or server. So during construction, you could install a normal lamp, then later add a Powerline sensor and a Powerline lamp connection or socket (possibly from KNX) and then define their locations via software.

Yes, that works. It’s called Digitalstrom. But it’s more expensive, much less flexible, and not as fast as KNX.

AleXSR700 schrieb:

Basically, it’s as if the Powerline electronics were simply inside the wall socket (the hardware). Then it doesn’t matter which device is plugged in, since you switch the power of the socket on or off. For a lamp and many other devices, it’s a simple binary principle. And for a lamp, roughly speaking, it’s not much more complicated than a conventional motion sensor. A motion sensor detects movement and then switches the built-in lamp on. For automation, it’s exactly the same, only the lamp is not built-in and thus a simple signal would go to the server, which switches the “socket” on, and that’s it.

Yes, that’s how it’s done in KNX. Only here, SELV (Safety Extra Low Voltage) and 230 V are separated. This has many advantages, some of which I already mentioned: reliability, response time, costs, etc.

AleXSR700 schrieb:

And an electrical network is generally more stable than a twisted pair cable. The wires are thicker, so there are fewer fault points.

No, that is also mistaken. It’s not about physical durability.

AleXSR700 schrieb:

As I said, I wonder whether the technology is the problem or if more complex solutions are being pushed because they are more profitable.

No, it’s the exact opposite. Simpler solutions are being promoted. KNX is already very simple. Star wiring and a bus cable, and everything is switchable and remotely controllable, possibly also wireless if you add an interface.

Yes, the technology and cost are the issues. With Powerline, you need more technology than with twisted pair.

AleXSR700 schrieb:

Running an additional cable is much more expensive after all.

No, it costs practically nothing in new builds because it’s pulled in along with the NYM cables. Maybe 100–200 euros more per typical single-family house.

AleXSR700 schrieb:

This is not an accusation, I’m just wondering why the more complicated and expensive path is chosen over such an elegant and universal solution like Powerline (given the very low bandwidth needed).

It’s the other way around. Powerline is far from elegant and universal, and also much more expensive than KNX over twisted pair.

AleXSR700 schrieb:

And an electrical grid is generally more stable than a TP cable. The conductors are significantly thicker, resulting in fewer points of failure.

Conductor thickness is almost irrelevant. Points of failure usually occur due to mechanical impacts. In that case, a standard cable would also be damaged.

AleXSR700 schrieb:

As I said, I wonder if the technology is the problem, or if more complex solutions are being pushed simply because they generate more profit. Installing an additional cable ultimately costs much more than just replacing the circuit breaker panel with a control unit.

My KNX knowledge is a bit outdated, so I’m definitely not up-to-date… but I’ll give it another try. Please correct me if necessary.

AleXSR700 schrieb:

Why is everyone turning away from the Powerline communication medium when it would be the most universal, elegant, and least complex method for the reasons mentioned?

In the Powerline solution you mentioned, a cable still has to be run toward the sensor. As far as I know, most KNX-certified sensors—or even all of them?!—are sufficiently powered by the bus voltage. This means you only need to lay the EIB cable to the sensor. In other words, there is zero additional effort.
The same applies to the switch.
a) You can completely eliminate batteries for 10 wall switches using a KNX switch—in theory, at least. Costs are comparable.
b) The switch only requires the EIB cable and no 230 V power supply. The EIB cable simply goes to the next switch/actuator or whatever. So cable length is not necessarily a factor either.
The only cables that will actually be longer are those for the loads—lamps, sockets, etc. These don’t typically run in a loop but usually go directly to the distribution board. In a normal house, this might mean extra costs of around 200–300€ (euros). Maximum.

The programming itself still needs to be done afterward with Powerline as well.

Oh, and just as a side note, Wi-Fi does not replace LAN cabling. Forget about terms like "power-line" adapters, repeaters, and so on. These have no place in a technically advanced new building.

... apart from the fact that KNX-PL (Powerline) is practically dead. One could briefly consider why a globally established industrial standard is moving away from this medium.