ComfoAir: heater control

I am running a ComfoAir 200 with integrated heater and frost protection.
The communication is done with ComfoAir Binding trough a serial connection (no separate control panel).
Till now everything looked good and working fine.

Now in the cold days I checked the frost protection and heater function.
My problem now is that the electrical heater does not work.
I saw that there are some values in the configuration for the heater but the are read only. So I can not give a specific value to heaterTargetTemperature.

Heater Values
heater#heaterPower Number Heater Power Heater power value true yes
heater#heaterPowerI Number Heater Power I-parameter Heater power I-parameter value true yes
heater#heaterTargetTemperature Number:Temperature Heater Target Temperature Target temperature of the heater true yes

Maybe someone can share some details how the heater-function is controlled with OH3?
At the moment I am running the newest milestone build openHAB 3.2.0.M5.

Thank you in advance. BR Sebastian

Ok, this was a misinterpretation from my side. My ComfoAir 200 has no heater, only a preheater register for frost protection, which is not controllable.
So… so far so good.