Calculating RMS value of data samples in RT

Question

I am using CompactRIO 9014 in my control application. I am acquiring data from NI 9215 module. I want to calculate RMS value of data coming from this module for monitoring of the system. I want to include data samples within 1sec to calculate RMS value. I am sampling at 25KHz rate. I want to use RT for processing there a way to do this? I am using Labview 8.6. 

Answer 1

suni wrote:
I am using CompactRIO 9014 in my control application. I am acquiring data from NI 9215 module. I want to calculate RMS value of data coming from this module for monitoring of the system. I want to include data samples within 1sec to calculate RMS value. I am sampling at 25KHz rate. I want to use RT for processing there a way to do this? I am using Labview 8.6. 
Hi suni,
Yes, you can do the processing on the RT host - that's actually the recommended way of doing things. I suggest using a DMA FIFO to transfer the data from your FPGA to the RT host, however you don't want to make your FIFO 25k elements long. Instead, you can write/read the FIFO in chunks (recommended size is under 8196 elements). Then, as long as you're reading from the FIFO at a reasonable rate on the RT, you should be able to pull out the elements and perform the RMS calculations. 
If you're new to FPGA, I highly recommend looking at the examples in Help > Find Examples > Hardware Input and Output > compact RIO. A lot of them demonstrate communication between the FPGA and RT hosts. 
Hope this helps! 
Misha