Hello everyone,
some of you might know that I’m new here and slowly getting familiar with the relevant topics. As a very tech-savvy person, I am particularly interested in automation.
I’m surprised that the current trend in advice for new builds leans towards connecting everything via bus cables. This involves a huge amount of planning with a very high likelihood of retrofitting over the next 30 years. A wireless solution or a powerline communication system would technically be completely feasible, requires much less planning, and involves hardly any extra work for the electrician. Every component to be controlled is powered anyway. Therefore, each component could be addressed via the regular power cable. And if someone wants to save a bit during construction, they could simply upgrade certain components like lighting later on and operate them manually until then. There are no additional costs for a non-smart installation of a light fixture.
Or is this already the case, and I have misunderstood the recommendations for implementing bus systems like KNX and others?
Best regards,
Matthias
some of you might know that I’m new here and slowly getting familiar with the relevant topics. As a very tech-savvy person, I am particularly interested in automation.
I’m surprised that the current trend in advice for new builds leans towards connecting everything via bus cables. This involves a huge amount of planning with a very high likelihood of retrofitting over the next 30 years. A wireless solution or a powerline communication system would technically be completely feasible, requires much less planning, and involves hardly any extra work for the electrician. Every component to be controlled is powered anyway. Therefore, each component could be addressed via the regular power cable. And if someone wants to save a bit during construction, they could simply upgrade certain components like lighting later on and operate them manually until then. There are no additional costs for a non-smart installation of a light fixture.
Or is this already the case, and I have misunderstood the recommendations for implementing bus systems like KNX and others?
Best regards,
Matthias
AleXSR700 schrieb:
But if the bus system does not have to be star-shaped, then my statement is obviously incorrect. I still don’t understand why you associate a bus with a star topology at all. While bus and star are not mutually exclusive, the core of a bus system is broadcasting, which is more typical for a common rail setup.
That’s why your unusual statement really got me curious for an explanation.
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AleXSR70018 May 2020 16:42@11ant
I probably added to my post after you had already replied. It was mentioned earlier in this thread (see my previous post), and my web searches repeatedly came across star or radial configurations.
That’s why I assumed that KNX systems always have to be set up in a star topology, which seemed very complicated and labor-intensive from my perspective.
I probably added to my post after you had already replied. It was mentioned earlier in this thread (see my previous post), and my web searches repeatedly came across star or radial configurations.
That’s why I assumed that KNX systems always have to be set up in a star topology, which seemed very complicated and labor-intensive from my perspective.
AleXSR700 schrieb:
I understood that only one actuator is allowed per line, which is why a star topology is necessary. And I found that extremely complex. No, KNX is the technology of choice. Basically, you can lay out the bus as flexibly as you want. However, closed loops are not "allowed" because they can cause ghost telegrams and other issues, so it’s better to avoid them.
An installation can look like this:
AleXSR700 schrieb:
I understood that only one actuator is allowed per line, which is why a star topology is necessary. And I found that extremely complex. That’s not the case. As I mentioned, star wiring and bus wiring. The bus wiring itself is basically free. Each switchable channel (if it’s switched from the distribution board) must be wired in a star topology, so using NYM cables, not bus cables. If you want to use decentralized actuators or plan to retrofit or expand later, you can also avoid star wiring here and connect everything in series—bus and NYM.
You encounter star wiring often when searching online because it is the preferred method for new installations on the NYM side, so that’s how it is done. The bus wiring is usually a mix of different topologies.
untergasse4318 May 2020 18:27"Bus" and "star" wiring terms often come from people who have looked into Loxone. With the green island solution, that’s how it was done (I know Loxone Tree exists, but it’s still Loxone). With KNX, you can wire it however you want as long as you don’t create a closed loop and don’t exceed the maximum cable lengths per line and between devices. However, this rarely happens in a single-family house. At this point, I would also recommend some basic reading on KNX or bus systems in general…
AleXSR700 schrieb:
I probably added to my post after you had already replied. However, the additional information didn’t clarify anything – when I saw it, it already said (and still says)
AleXSR700 schrieb:
A bus system has a star topology. Therefore, only one end device per connection. At that point, I was hoping you could enlighten me, either by explaining how you revolutionized network topologies or where you got that mistaken assumption from.
A bus is actually a network topology on its own, which competes with the star topology without overlap; and very closely placed outlets that can be perceived as a double outlet are not excluded here. For one, non-experts often perceive folded buses as stars; and on the other hand, the term “bus” has become common as a traffic designation even for systems that are not actually buses but just share some of their characteristics: saving conductors, allowing multiple tap connections at relatively many points, broadcast communication (including selective addressing).
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AleXSR70019 May 2020 16:24Yes, this shows that you can know a lot but still miss some "small" details. I had only understood the term bus as a communication pathway between two components. And that is technically incorrect. Until now, I wasn’t aware that a bus is actually a topology. That’s why I simply thought of the “bus” as just the data line.
Learned something new again.
Learned something new again.