Hello again,
in the meanwhile I had a PM regarding this issue from another forum member. He made a very valid observation, the 184 in the 1st line at boot up with the two characters before is obviously the model number KP184, that did not click with me ;-) The 2nd line shows 2020 and the 3rd the address 1. For clarification I add a picture of it below the post. I also have a picture of the board version added for convenience. It appears to be Version 4 202007. So I am definitely not the only one with the issue, there appear to be at least 2 other forum members with the same issue according to the PM I got. I am not going to quote a PM here, I leave that to the person that send me the message if he things it is of any help to the issue.
I hope we can get to the bottom of the issue and fix it in the end. It's not the end of the world for me, I appear to be lucky enough to have an otherwise working instrument which does not seem to be the case for some people. The serial communication would still be a nice extra to have.
Thank you !
Jan P.
PS: Hi @interflexo, thanks for the hint re the Version 5 PCB. I got my unit only a week ago but may have been in stock for some time at Banggood ES warehouse where I got mine from (EU citizen). The KP283/284 looks way different of the control side of things, a lot simpler I guess. Not sure if any parallels could be drawn there apart from maybe the high power side of the instrument.