Time synchronization of two DAQmx signals with the resulted RMS signals

[alf21]

Hi.

I’m trying to synchronize two DAQmx signals (Voltage and Current) with the resulted RMS signals (Statistics VI).  The sampling frequency of the two DAQmx signal is correct but for the other two (resulted from the RMS function) is much more less.  When I open the saved data, the two RMS signals were sampled much less frequent.

Any suggestions will be appreciated.

Thanks!

[Dennis_Knutson]

I don't understand the issue. If you take x number of samples and get an RMS value, then obviously you will only have a single RMS per acquisition.

You might want to attach your code and a sample of the saved data to further explain what you want.

[alf21]

Hi Dennis,

Attached is the VI.  It calculates the power from two DAQmx signals.

I just want to save the power signal more frequently.  Right now, it is saving 1 sample per second.  I’ll like it to be around one sample every millisecond.  Is there any way that I can control the samples to be used for the RMS calculation?

Thanks in advanced.

[johnsold]

What is limiting the timing to once per second? The DAQ Read could happen as often as 10 times per second with the values in your controls. Your GPIB instrument may be slow.  Writing to 4 files (with opening and closing each time) is probably slow, especially as the files grow.

Next. RMS calculations on less than one cycle of the input signal are meaningless. Getting RMS calculations at a millisecond rate on data sampled at 10 kHz is completely unrealistic.

Lynn