Using RMS block from FPGA math and analysis tool box

[kprabaka]

Hi, 

  I am using sbrio 9642 to measure a 60 hertz sinusoidal voltage waveform. I would like to calculate the dc and RMS value of this signal. I am applying a signal with an RMS of about 1.73 V. But, the RMS results from the FPGA is oscillating around 1.69 to 1.71 V. I would like the FPGA to accurately measure the RMS value. I have attached the pictures of my code and also the configuration of the RMS block with this discussion. 

The time between conversions in the NI 9205 analog input is set to be 8 micro second. Because of this, I have given 125Ks/s and also since I am measuring a sinusoidal waveform of 60 Hz frequency, I have used 16.664 m seconds in my measurement time.

Any help would be appreciated. 

- Kumar

[srm@viewpointusa.com]

check the actual loop rate.  i suspect you are not running at the rate that you think you are therefore not collecting one cycle of data