That integrated max3232 is a great buy! There is indeed too much confusion on this as TTL has been mentioned in this thread. The Zehnder manuals are clearly stating if it's RS232 or RS485. You'll be fine as our WHR 930/950 units are definitely equipped with RS232. (https://zehndernl.zendesk.com/hc ...

@rrozema, if you want to make it easy for yourself get a "db9 breakout connector" and a USB to RS232 DB9 converter. Then find yourself an Ethernet cable and connect it like this (TX/RX is from comfoair perspective):

I have a working esphome comfoair plugin now. My esp is powered by the WHR-950 and is natively communicating with home assistant. Esphome can also talk to an mqtt endpoint, so this should work with domoticz as well.. Note: I destroyed the transistors on the WHR mainboard by using an RJ45 female ...

Ok, I finally got it working. I actually did break the RS232 logic conversion part of my WHR-950 Basic, I fixed this by replacing both the BC847B transistors. Now I can finish my esphome comfoair plugin . @rrozema I noticed you're using the FT232RL chipset, this is for a TTL level device (0-5V), you ...

I have spent another sunday on this and I think I have to admit defeat: my WHR930 won't talk to me. I don't know what is wrong, but I've tried everything I can thik of and read here in this thread and it never responds. I have the same problem (WHR 950 II) with the exact same board layout as yours ...