Hi rolfk,
Thank you for this hint – I tried to use P and p but this has no effect.
But it is good to know that such an experienced user as you thinks that my vi should work.
Due to the responses here, I think at the moment that I do something wrong with the device itself.
So, tomorrow I will meet a guy who has used this balance successfully together with a computer (decades ago ;-).
I will keep you up to date when I have new information!