Dear cbutcher,
Thank you so much for your idea to use a timeout error.
As written, there is no timeout error – but your idea inspired me to use the vi
"niScope Acquisition Status".
This vi tells you if there was an acquisition or not. By rewriting my code a bit, I managed to use this vi as a workaround. Now my program has the same behavior as when I use the trigger mode Norm/Auto in the NI-SCOPE Soft Front Panel.
So, I found a nice and easy solution for my problem.
Thanks for your inspiration!