To make the Sketch work and upload it it took a lot of "USB plugged out USB plugged in" and reset.But since added the Bihor no serial seen anymore.
I read that it is possible that COM will not work anymore if the loop do not have delays?There is one in the sketch (delay(100)).
How to really reset the UNO? Not restart with custom sketch to get the UNO back I removed yesterday from the package?A RESET button should RESET the WHOLE system and make everything work the way it came from factory and not restart system with custom software. In my case, I guess, this would avoid a lot of trouble.
The UNO OS should also have enough CPU time to serve the native UNO functions like COM handling. I guess that this is an issue but I will try in the next step to remove all of my work from GND.
Nice device but for kids too much trouble. Plug and Play would be nice. However when it works it's really great.