The news is much better than you fear. The TTL pulses produced by your device are best measured by your DAQ board's counter(s), which are spec'ed up to 20 MHz for input (source) pulses. Looks like you should be ok. (Note: the 200 kHz spec refers to the maximum analog input sampling rate, and isn't likely relevant to your app.)
What you'll probably need to do is configure one counter for either buffered edge counting or period measurement with your device pulses wired in as "timebase source" signals. These will cause the internal count to increment. Your other counter will need to generate a continuous pulse train that will act as a sampling clock. This will cause count values to be buffered in memory at a precise rate.
Search these forums for terms like "photon" -- the topic has come up numerous times and there's quite a bit of helpful info to be found.
-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.
