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Question about ENCODER GET.VI Rate output

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  • Question about ENCODER GET.VI Rate output

    Question about ENCODER GET.VI Rate output
    The LV help file states: “… Rate returns the rate, in Hz, of pulses of the encoder. …” I interpret this as pulses per second. The question is: Over what interval is this rate computed i.e. pulses per unit time? If the input rotational rate of an encoder is suddenly increased in a step to a new value, say from 128 pulses per sec to 256 pulses per sec what will the RATE output of the GET.VI report if read every 10ms or every 50ms?
    TNX for your help.

  • #2
    Re: Question about ENCODER GET.VI Rate output

    See the readme in C:\Program Files\National Instruments\LabVIEW 8.5\readme\readme_FRC.html, specifically the section on documentation corrections.

    The Rate output of the Get VI on the Encoder palette returns the rate, in distance units per second, of pulses of the encoder. Use the DistancePerCount input of the Open VI to specify the distance units you want to use.
    The Get VI will return the correct rate no matter at what rate it is called.
    Team 330 beta tester

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    • #3
      Re: Question about ENCODER GET.VI Rate output

      Originally posted by jboette View Post
      Question about ENCODER GET.VI Rate output
      The LV help file states: “… Rate returns the rate, in Hz, of pulses of the encoder. …” I interpret this as pulses per second. The question is: Over what interval is this rate computed i.e. pulses per unit time? If the input rotational rate of an encoder is suddenly increased in a step to a new value, say from 128 pulses per sec to 256 pulses per sec what will the RATE output of the GET.VI report if read every 10ms or every 50ms?
      TNX for your help.
      The rate is computed based on each pulse by counting how many ticks of a faster clock (1MHz) passed between encoder pulses. That means if you change in a step, the rate output will also. If you enable averaging, however, then the sliding-window average will be returned and the rate will change more smoothly.

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      • #4
        Re: Question about ENCODER GET.VI Rate output

        TNX for your informative response. It clears up and settles a lot of discussion we've been having concerning the Rate output. TNX agn.

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