The high and low levels are dictated by the hardware and cannot be changed. It's compatible with TTL logic, meaning that low levels are generally near 0 V and high levels are more like 5 V. Rise and fall times are also specified as very short durations (sharp edges).
If instead you want to set the high and low TIMES of a pulse train, there are inputs available in DAQmx Create Virtual Channel that let you define the timing characteristics of a pulse train.
-Kevin P.
ALERT! LabVIEW's subscription-only policy came to an end (finally!). Unfortunately, pricing favors the captured and committed over new adopters -- so tread carefully.
