Calculates the DC and RMS values of an input waveform or array of waveforms. This VI is similar to the Basic Averaged DC-RMS VI, but this VI gives more precise control over the individual DC and RMS calculations.

Wire data to the signal in input to determine the polymorphic instance to use or manually select the instance.


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Inputs/Outputs

  • cbool.png reset —

    reset resets the history of your time signal. You typically use reset to reset the exponentially averaged measurement.

  • cmsdt.png signal in —

    signal in is the input waveform.

  • cenum.png averaging type —

    averaging type is the type of averaging used during the measurement. If averaging type is exponential, this VI calculates the DC and RMS values using an exponentially weighted averaging measurement starting from the previous DC and RMS values.

    0Linear—Averaging time is equal to the record length.
    1Exponential—Time constant is half the record length.
  • cdbl.png averaging time —

    averaging time defines dt of DC value waveform and RMS value waveform in seconds. The default is –1.00, which corresponds to average time = input block duration.

    For linear averaging, each output data point results from performing the averaging process for the time period specified by averaging time. For exponential averaging, each output data point results from exponential integration performed for the time period specified by averaging time using exp. time constant.

  • cerrcodeclst.png error in (no error) —

    error in describes error conditions that occur before this node runs. This input provides standard error in functionality.

  • ccclst.png averaging control —

    averaging control contains the advanced parameters used to completely control the DC or RMS measurement.

  • cenum.png window for DC —

    window for DC is the window to be applied to the time record before DC computation. LabVIEW ignores this input if averaging type is exponential.

    0
    Rectangular
    (no window)
    1
    Hanning
    2
    Low side lobe
  • cenum.png output function —

    output function selects the type of measurements to be performed.

    If you need only DC or RMS measurements, selecting these components separately increases the processing speed.

    0
    DC only
    1
    RMS only
    2
    DC and RMS
  • cenum.png window for RMS —

    window for RMS is the window to be applied to the time record before RMS computation. LabVIEW ignores this input if averaging type is exponential.

    0
    Rectangular
    (no window)
    1
    Hanning
    2
    Low side lobe
  • cdbl.png exp. time constant —

    exp. time constant specifies the time constant (RC) of your DC or RMS measurement.

    exp. time constant equals –1.00, which corresponds to a value of input block duration/2.

  • cbool.png Ignore input start time —

    Set Ignore input start time to TRUE when you do not want the VI to check for continuity using t0 values.

  • ibool.png data ready —

    data ready indicates the DC value waveform and RMS value waveform contain data. A value of FALSE means the waveforms do not contain data.

  • imsdt.png DC value waveform —

    DC value waveform indicates DC values of signal in computed over averaging time seconds and time stamped continuously from the last reset.

  • imsdt.png RMS value waveform —

    RMS value waveform indicates RMS values of signal in computed over averaging time seconds and time stamped continuously from the last reset.

  • ierrcodeclst.png error out —

    error out contains error information. This output provides standard error out functionality.

  • icclst.png measurement info —

    measurement info returns information about your measurement, mainly warnings for inconsistencies in your input signal.

  • idbl.png uncertainty —

    uncertainty is reserved for future use.

  • ibool.png Warning —

    Warning is TRUE if a warning is generated during processing.

  • istr.png comments —

    comments contains a warning message when Warning is TRUE.

    • This VI is designed to process a single channel or multiple channels continuously, typically from within a For Loop or a While Loop.

    Note The Averaged DC-RMS VI assumes that consecutive data blocks are continuous. If they are not, the VI returns a warning in measurement info, unless Ignore input start time is enabled.

    Examples

    Refer to the following example files included with LabVIEW.

    • labview\examples\Signal Processing\Waveform Measurements\Advanced DC-RMS Measurement.vi