Digital Multimeters (DMMs) and Precision DC Sources

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Frequency measurement takes too much time


        I'm using a NI PXI-4070 to measure a signal of 10KHz square waveform with 5V amplitude(from keysight 33500B waveform generator). I programmed with Visual C and just modified from the NI example. I set the minimum frequency as 999Hz so that the aperture time was 2000/999=2.2ms, but it took more than 500ms to read the frequcny. I also set the same parameter in NI-DMM soft front panel, the measure result updated very quick(at least less than 500ms). I test both the function niDmm_Read and niDmm_Initiate/niDmm_Fetch, both of them took more than 500ms. 

       Can somebody help to check where I'm wrong? thanks.




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An application called I/O Trace should have been installed along NI-DMM in your system. It will trace all calls made to the NI-DMM (and other) APIs. A good tip is to use this to see how the Soft Front Panel configures the device as you use it.


Also, you should check out InstrumentStudio if you haven't yet, a modern replacement for the NI-DMM Soft Front Panel.

Marcos Kirsch
Chief Software Engineer
NI Driver Software
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