Hi @Peppe66
This is what I’ve done with a Shelly Uni instead of the Plus Addon.
Maybe it help’s you.
https://community.home-assistant.io/t/water-meter-with-shelly-uni/567365
With the Addon it could work too but if you use an inducive sensor you need another power source for the higher voltages of the sensor. The Addon only provides 3.3V.
d.k