Hi C.R.,
You can use any example program that uses buffered period measurement with 1 counter. What happens is that every time your TTL signal goes through 1 period, that value is latched into the buffer. If you have a small buffer, your program will be reading this buffer in quite often. You can then take the inverse of the period measurements to get the frequecy. The advantage of using a buffered period measurement with a counter is that it is continuously getting the instantaneous frequency of each period. By latching into the buffer, you can take an average of the buffer to get a more normalized value. Check the shipping examples of your software package for these examples or go to ni.com/support and click on Example Code link to search for examp
les. Anyway, hope that helps.
Ron
