Counting pulses and measuring flow rate per second

Hi everyone

I am using a compactField Point (cFP-2220) controller to measure the flow rate. The flow sensor that i have, gives the output in terms of the pulses. I need to count the number of pulses for a particular interval and divide it by a K-factor( constant value) to get the flow rate. If i select the interval to be of a second, i would want to count number of pulses per second and divide it by K-factor to get flow rate ( per second). 

How do i count pulses per second and consequently measure flow rate using this count and K-factor.

Any kind of help would be highly appreciated.

Thanks in advance.