I have a fpga, a pxi system and a daq.........My idea is to change the refresh rate  
  
I have to actually change therefresh rate with changes in input frequency frequency....My refresh rate is calculated as follows.  scan rate=40Mhz/16*fin for example for an incoming frequency of 10 khz, my scan rate would be 250 If suppose the incoming frequency is changed, I want the scan rate to be  changed automatically so that the frequency of the look up table is updated. 
 
How should this be done?