How to count with PCI-6601 for short periods, quickly?

[physics_is_cool]

The application I have in mind is to count TTL pulses for short periods (~500 us) at a rate of ~2 kHz to use in an FFT. I haven't been able to find a way to code something like this... I've tried using DAQ assistant with edging counting for N samples. I also have a program that opens a to port to one of the counters on the card and counts for a specified time, but this is inside a for-loop and I don't have control over the frequency of the sampling. How can I make such a program?

[KateB]

Try Help>>Find Examples>>Hardware Input and Output>>DAQmx>>Counter Measurements>>Count Digital Events>>Count Digital Events-Buffered-Finite-Ext Clk-Count Reset.vi, but you'll need to generate 2kHz clock from another counter channel.