Dear NI Community I'm new to using the LV FPGA for DAQ tasks and I have a few questions relating to filtering the data. Any assistance would be greatly appreciated. I have attached my LV2020 FPGA VI, where I am using 2x9237 cards to measure 6x strain signals split equally across the two cards due to the power limitations. To specify the scaled coefficients for the Butterworth filter you need to know the sampling frequency and desired cut-off frequency. Presumably if you set the data rate for the module at say 1.613S/s then you will get 1.613 div 3 S/s = 537.6 S/s on each of the three inputs? When you create a control for the scaled coefficient inputs it looks like the values have already been calculated? I did do a check using the Butterworth Coefficients Express VI and the numbers are quite close. If they are already calculated internally do you still need to provide a control? I would imagine the filtering functions increase the computation time for each loop. Does this ultimately affect your sampling rate seen at the RT program? So is it necessary to increase the data rate to compensate for any lag coming from the filtering functions?

LabVIEW

9237 FPGA Data Filtering

Dear NI Community

I'm new to using the LV FPGA for DAQ tasks and I have a few questions relating to filtering the data. Any assistance would be greatly appreciated.

I have attached my LV2020 FPGA VI, where I am using 2x9237 cards to measure 6x strain signals split equally across the two cards due to the power limitations.

To specify the scaled coefficients for the Butterworth filter you need to know the sampling frequency and desired cut-off frequency. Presumably if you set the data rate for the module at say 1.613S/s then you will get 1.613 div 3 S/s = 537.6 S/s on each of the three inputs?
When you create a control for the scaled coefficient inputs it looks like the values have already been calculated? I did do a check using the Butterworth Coefficients Express VI and the numbers are quite close. If they are already calculated internally do you still need to provide a control?
I would imagine the filtering functions increase the computation time for each loop. Does this ultimately affect your sampling rate seen at the RT program? So is it necessary to increase the data rate to compensate for any lag coming from the filtering functions?