ian332isport:
I mentioned it before, but have you got TH3122 tx going to Arduino tx, and TH3122 rx to Arduino rx?I know you normally cross these with most devices, but not with the TH3122.
This may be why SEN/STA isn’t working.
Interesting. I have them crossed as conventional. I will try it again disconnected initially and see if the Status line toggles then.
If they were the wrong way round though, surely the receive functions wouldn't then work either?