Creates a channel to measure the period of a digital signal. With the exception of devices that support multi-counter tasks, you can create only one counter input channel at a time with this VI because a task can contain only one counter input channel. To read from multiple counters simultaneously, use a separate task for each counter. Connect the input signal to the default input terminal of the counter unless you select a different input terminal.


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Inputs/Outputs

  • cu32.png divisor —

    divisor is the value by which to divide the input signal when measurement method is Large Range with 2 Counters. Leave this input unwired if measurement method is not Large Range with 2 Counters.

    The larger the divisor, the more accurate the measurement. However, too large a value could cause the count register to roll over, which results in an incorrect measurement.

  • ci32.png measurement method —

    measurement method specifies the method to use to calculate the period or frequency of the signal.

    High Frequency with 2 Counters (10157)

    Use two counters to count pulses of the signal to measure during measurement time.

    Large Range with 2 Counters (10205)

    Use one counter to divide the frequency of the input signal by divisor to create a lower-frequency signal that the second counter can more easily measure.

    Low Frequency with 1 Counter (10105)

    Use one counter that uses a constant timebase to measure the input signal.

    Dynamic Averaging (16065)

    Uses one counter and automatically configures the counter settings based on the range of frequencies to be measured. During the acquisition, the counter dynamically adjusts the number of periods that are averaged to balance measurement accuracy and latency.

  • cdbl.png minimum value —

    minimum value specifies in units the minimum value you expect to measure.

  • cdbl.png maximum value —

    maximum value specifies in units the maximum value you expect to measure.

  • cgenclassrntag.png task in —

    task in specifies the task to which to add the virtual channels this VI creates. If you do not specify a task, NI-DAQmx creates a task for you and adds the virtual channels this VI creates to that task.

  • cdaqmxscale.png counter —

    counter specifies the name of the counter to use to create the virtual channel. The DAQmx physical channel constant lists all physical channels, including counters, for devices installed in the system.

  • cstr.png name to assign —

    name to assign specifies a name to assign to the virtual channel this VI creates. If you do not wire a value to this input, NI-DAQmx uses the physical channel name as the virtual channel name.

    If you use this input to provide your own names for the virtual channels, you must use the names when you refer to these channels in other NI-DAQmx VIs and Property Nodes, such as the source input of the DAQmx Trigger VI.

    If you create multiple virtual channels with one DAQmx Create Virtual Channel VI, you can specify a comma-separated list of names to assign to the virtual channels. If you provide fewer names than the number of virtual channels you create, NI-DAQmx automatically assigns names to the virtual channels.

  • ci32.png units —

    units specifies the units to use to return time or period measurements.

    From Custom Scale (10065)

    Units a custom scale specifies. If you select this value, you must wire a custom scale name to the custom scale name input.

    Seconds (10364)

    Seconds.

    Ticks (10304)

    Timebase ticks.

  • cerrcodeclst.png error in —

    error in describes error conditions that occur before this VI or function runs.

    The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. If an error occurs while this VI or function runs, the VI or function runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.

  • cdaqmxscale.png custom scale name —

    custom scale name specifies the name of a custom scale for the channel. If you want the channel to use a custom scale, wire the name of the custom scale to this input and set units to From Custom Scale.

  • ci32.png starting edge —

    starting edge specifies between which edges to measure the frequency or period of the signal.

    Falling (10171)

    Measure between falling edges.

    Rising (10280)

    Measure between rising edges.

  • cdbl.png measurement time —

    measurement time is the length of time in seconds to measure the frequency or period of the signal if measurement method is High Frequency with 2 Counters. Leave this input unwired if measurement method is not High Frequency with 2 Counters.

    Measurement accuracy increases with increased measurement time and with increased signal frequency. If you measure a high-frequency signal for too long, however, the count register could roll over, which results in an incorrect measurement.

  • igenclassrntag.png task out —

    task out is a reference to the task after this VI runs. The task contains any newly created virtual channels. If you did not wire a value to task in, NI-DAQmx automatically creates the task this output refers to.

  • ierrcodeclst.png error out —

    error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, error out describes the error status that this VI or function produces.

    Right-click the error out indicator on the front panel and select Explain Error from the shortcut menu for more information about the error.