STIEBEL ELTRON ISG with modbus-Binding don't get all channel values


i have a new heatpumpt from STIEBEL ELTRON with an ISG (Firmware 12.1.2) and the EMI (Energie Management Interface) Add-On installed. I read sometimes, that ins this constellation Modbus ist not offered any more from the ISG. But I got a connection with openHAB 4.0.4 and the Modbus binding to the ISG and also values for outdoor temperature, or the energy consumption and creation (heating and warm water). Yesterday, I tried to add the channels for the set points or HK temperature. The result is for all additional channels “0°C”. Normally I would need also an HK2, which is not offered in the moment from the binding. I found a thread about direct Modus communication with STIEBEL ELTRON yesterday, but I did not understand fully what to do, so perhaps it is better to solve, why the offered channels deliver no real values.

There is separate documentation about ISG modbus registers. Based on this document you can source valid register addresses and use them with modbus binding. Since ISG can work in several constellations there are overlapping register definitions which might be populated depending on installation components.
As far I remember isg binding in openHAB supports only subset of registers/controllers which are most popular.

Do you have ISG documentation?

Yes, I have downloaded the document, but there are different versions and I did not have worked with modbus before. It is like a complete other language for me. The most important thing for me is to know, if it could work or not, because of the EMI module.

I attached two screenshots, I got the outdoor temperature, but not the hk1 temperature:

So every heat pump should have a value for HK1…?

I am not an expert in area of stiebel, but EMI is a ISG application, which might take care of water tank or buffer, but not necessarily about comfort setpoints (unless SMA part does it?).

The relevant part in this regard is - there are repeated modbus registers which might be populated depending on controller you have (WPM3 / WPM3i) and room thermostats. From what I remember some of these are available if you have specific components in your installation.

Have a look in docs - HK1 setpoint can be controlled with registers 509 (WP-M system and WPM 3) / 510 (WPM 3i) but also 1502 (comfort setpoint) / 1503 (eco setpoint).