I have almost finished all the wiring involved and will be turning on my sunny islands with five of these bms's attached. There is no "sma" protocol to choose from in the bms settings, so I'm really unsure of how it works. I assume I choose a different protocol, like goodwe or victron and it will also be compatible for sma inverter comms. It is difficult finding any information but I will let you know. I think I just have to experiment with the protocol selections and see which one gives the most/correct info back to the inverter.