Unfortunately the manual is only available in German at the moment.
On site 4 you will find a drawing of the PCB.
Temperatursensor => temperature sensor
Tachosginal => rpm signal
Durchflusssensor => flow sensor
aquabus 1/2 => aquabus 1/2
Leitungsausgang => power output
Stromversorgung => power supply
If you have any specific questions feel free to ask.