Thanks for all your hints!! - unfortunately this is not the issue as well (I've tried all variables everywherer..

Maybe I failed to explain the problem correctly: How do I send information from my pyboard to a program running on my PC (the latter being written in python, of course...).
I connect by USB cable using screen to the pyboard. When I enter tmp = usb.send(b'testup') - I want the string "testup" to appear in the programm running at my pc and not on the pyboard in the variable tmp.
Any ideas?
Greatings from Hambug to Canada!
Ulrich