Daq class interprets negative events as finite-length scans

[ZLLentz]

Expected Behavior

events=-1 should work as an infinite length scan and be identified as such in all cases OR events=-1 should be a rejected input

Current Behavior

events=-1 does work as an infinite length scan, but is identified as finite-length because bool(-1) is True

[ZryletTC]

I vote for the first option: events=-1 works as infinite length

[klauer]

So:

• Overall check assert events >= -1, 'Invalid event count'
• is_infinite_length_scan = events in (-1, 0)

[ZLLentz]

:+1: I may work on this today, but it would wait till the PAMM to do a full test.