Starting Openhab mit KNX - Beginner question

[MartinKo (Martin Korsrud)]

Cool, Thanks

[lintec (Nico Gripp)]

First of all thank you for all the answers. What a great community

Is there any cheap and easy alternative for switching some relais (ca. 10) on and off with openHAB?

[halloween]

Maybe some of this:

https://www.itead.cc/smart-home/sonoff-4ch.html
https://www.itead.cc/smart-home/sonoff-4ch-pro.html

I would only switch relais, not directly connected to the power circuit. Because there are some problems with exploding sonoff switches - bad soldering - not enough for high loads.

But if you only want to switch relais, there should be no cheaper way without soldering it by yourself.

[lintec (Nico Gripp)]

Okay, and this product can be connected to openHAB?

Edit: And by the way. It doesn’t depend on a few Euros…

[halloween]

You can search in this forum for sonoff. You have to flash the sonoff devices with tasmota firmware and so you can control it with openhab and mqtt.

You don´t need any gateway, it is working with wifi.

[lintec (Nico Gripp)]

Is there anything similar with ethernet connector?

[halloween]

Maybe with a raspi and a 10-channel relais board?

[binderth (Thomas Binder)]

@lintec

I will use it in our company primary and asked our electric wholesaler for his opinion. He told me to consider KNX because of it’s great scalability.

That’s what makes me a bit nervous, recommending anything other than a robust solution. It’s out of a “HOME”-automation, and therefore I recommend strongly to use industry standards. KNX is here the way to go - even if it’s more expensive. Talk to your company electrician about your goal and he surely will help you on this.

@lintec

reading some energymeters and our photovoltaic earnings

There are also KNX-capable readers you can use - they are also more expensive than those for home use, but are independent and are more easy to implement.

@lintec

I do will have 5 groups of light which are separated in 2 levels each.

As explained, this would be done by simple switch actuators (I guess, you won’t need dimmer?) which are easy to implement.

@lintec

I want to switch them on and off via PIR sensors and switches for 2-3 different “light-scenes”.

as Udo already pointed out, to be on the safe side (and I also assume, the PIRs are outside), you should have two lines, to avoid sabotage.

To sum it up: If you feel the need of changing anything yourself, you should consider having a dedicated ETS licence for you. You should also have your electrician doing the cable work (you’re not allowed to do this in your home, so I would avoid doing this at work even more!) and he could also setup your KNX project. He can show you the configuration and you can continue the non-cable configuration.
In every case, you can add openHAB as a logic within, but honestly - I see it only for visualisation. The PIRs communicate with the actuators, wich switch on the lights. The readers communicate with the KNX and put all information there.
openHABs Job would then be to show you the lights’ states and the reader information. You could add some logic if you like, but what would be in there?

[maxico (Maximilian Scheiner)]

Maybe another quite cheap solution ist tinkerforge

some of the outputs to command the relays https://www.tinkerforge.com/de/doc/Hardware/Bricklets/Industrial_Digital_Out_4.html
connected to a
https://www.tinkerforge.com/de/doc/Hardware/Bricks/Master_Brick.html
which itself is on a stack with a network extension
https://www.tinkerforge.com/de/doc/Hardware/Master_Extensions/Ethernet_Extension.html

with the other bricks available you can monitor or control a lot of other things.

Disadvantage: you loose the status of the relay if you only comand the relay - a solution can be a relay with two outputs where one is connected to an input from tinkerforge to read the status.