ModBus (TCP) or ProfiBus Hardware compatibility

at first I will say Thank You for all the great work on OpenHab!

I’m a Beginner with OpenHab and for now I use a RPi3 with some Homemade MQTT Sensors and Actuators without Problems.

I look for a Wired Homeautomation System for the Switch cabinet.
There are “Homematic Wired” from ELV but I think this System is not good for further Extensions.
I think KNX is to expensive and need a lot of configuration outside of OpenHab

I’ve looked at Industrial PLC Controller from WAGO750-342 or Beckhoff BK9000 or Phoenix Contact.
All these Controllers use Ethernet with a Modbus TCP protocoll. They are not to expensive and you get many of extension Modules e.g. 0-10V Analog Outputs, Digital IN/Outputs…

Now my Question: Can I use any of these Ethernet Controllers directly with OpenHab Modbus Binding?
I want not to programming the PLC (except of IP’s)

There are also many “Profibus” Controller (also from Wago750, Beckhoff BK3100 and Siemens ET200),
but i’m not shure if this will work with Openhab, Is this a Interface Problem or a
License Problem why threre is no “Profibus” Binding via RS485 over Serial on RPi?


If you don’t want to program PLC, why not use simple Modbus slaves directly controlled from Openhab ?

Thank You for this Information!
I checked it out and it looks be okay for my solutions, The slave address is also programable (1-FE).
Have you these Modbus slaves in use and can you give me some feedback of the durability?

Perhaps you misunderstand me of programming the PLC’s (English is not my Motherlanguage): Programming of base features (IP, address,…) is not the problem, but i want not buy additional Software/Hardware and have trouble to get the PLC’s “talk” with OpenHab.

I have a few of those blue chinese Wellpro brand digital IO and relay units in service, no problems so far. There are other brands, similar to the more expensive Advantech Adam originals.
I do not use them to switch mains lighting directly, the lights are wired to impulse relays. The modbus units control and monitor those, alongside wall switches.
My inputs are from cheap burglar alarm type PIR sensors.

I have no idea what is needed to program a PLC so that it can exchange information and commands with Openhab. I didn’t see any need for a PLC if Openhab is doing the ‘smart’ work, so long as I have a simple “emergency” fallback (the wall switches).

To exchange Modbus traffic with OH, the PLC would need to take the slave role (on that interface) - OH can only be master at present.

Okay, thanks for Feedback
I will try these ModBus slaves.

Thats my Mistake I haven’t Explained it right, Sorry!
BTW: these PLC are not real Controllers (in German: SPS) these are only Fieldbus couplers via Profibus, CANOpen,TCP or other Versions(in German: Feldbuskoppler). Sometimes it is called “PLC” in English.
These are always Slaves (except of some special Version’s with inbuild real PLC).
These are only “translate” the BUS Signal in Digital In/Outs or Analog IN/Outs.

I have also a little problem to understand the Physical interface to my RPI3 GPIO’s. (OH 1.8.3)

I have a little RS485 Module like this:

Can I use this for the Modbus Serial Binding? If yes how should i connect the DE and RE Pins for the FlowControl, I see" flowControlIn" and “flowControlOut” but i don’t know the arguments for the GPIO Pins. I cant found it in de descrition for the Binding.
Or is it necessary to use a USB > RS485 Module? like this:

OK, a TTL to RS485 serial board. You would somehow have to make the Pi use some GPIO pins as a TTL serial interface. That’s a Pi thing, not OH, I have no idea how. The Pi system would need to make the software interface available to OH as a ‘tty3’ or similar port.

Given these things are really cheap, you would need a good reason not to do it that way.