Hi Peter,
Unfortunately not. The following knowledge base describes how a pulse train is output from the counters on the 6602 cards (NI-TIO Counter/Timer Chip). I just submitted the knowledge base so it might take a day or two to get pushed live.
How Do I Scale The Frequency Of My Pulse Train Using A Counter?
http://digital.ni.com/public.nsf/websearch/A04E7F1CB065279786256DB10071A151?OpenDocument
The only way to do what you are requesting is to have software read your file in real-time and change the frequency of the counter output on the fly. This will require your custom software program to determine the frequency at each point and make an update call to the counter to update the frequency to this point. This is limiting because the fastest softwa
re processing loops usually only run at around 1ms. Therefore, if your signal changes frequencies at a rate faster than roughly 1ms, software will not be able to update the counter in time. This counter application is called "switch cycle". I've included another knowledge base that describes this scenario as well.
How Do I Change The Frequency Output Of My Pulse Train On The Fly?
http://digital.ni.com/public.nsf/websearch/7B1B0427C39FE33086256CEE00752133?OpenDocument
Hope my suggestions help. Have a good day.
Ron
Applications Engineer
National Instruments
