Table Of Contents

Pulse Time and Transition Measurements (Transition) (G Dataflow)

Version:
    Last Modified: March 31, 2017

    Accepts an input signal of a single waveform or an array of waveforms and measures the transition duration, undershoot, and overshoot of a selected positive or negative transition in each waveform.

    connector_pane_image
    datatype_icon

    signal

    The input signal.

    This input can be a waveform or an array of waveforms.

    datatype_icon

    polarity

    A value specifying whether to measure a rising or falling transition.

    Name Value Description
    Rising 0 The node measures a rising transition.
    Falling 1 The node measures a falling transition.

    Default: Rising

    datatype_icon

    edge number

    The transition to measure. An edge number of n with rising polarity selected indicates that the node measures the nth rising transition it detects in the input waveform.

    datatype_icon

    reference levels settings

    High and low reference levels required to determine the transition interval.

    datatype_icon

    high ref level

    High reference level of the waveform.

    A rising high ref level crossing defines the end of a rising transition and a falling high ref level crossing defines the beginning of a falling transition.

    Default: 90

    datatype_icon

    mid ref level

    Middle reference level of the waveform.

    mid ref level is not used in transition measurements.

    Default: 50

    datatype_icon

    low ref level

    Low reference level of the waveform.

    A rising low ref level crossing defines the beginning of a rising transition and a falling low ref level crossing defines the end of a falling transition.

    Default: 10

    datatype_icon

    ref units

    Units of the high, middle, and low reference levels.

    Name Value Description
    absolute 0 Interprets the reference levels as absolute levels.
    percent 1 Interprets the reference levels as a percentage of the full range of the waveform.

    Default: percent

    datatype_icon

    error in

    Error conditions that occur before this node runs.

    The node responds to this input according to standard error behavior.

    Standard Error Behavior

    Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

    error in does not contain an error error in contains an error
    If no error occurred before the node runs, the node begins execution normally.

    If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

    If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

    Default: No error

    datatype_icon

    state levels settings

    Settings that determine the high and low state levels of a waveform.

    datatype_icon

    method

    Method this node uses to compute the high and low state levels of the waveform.

    Name Description
    histogram Returns the levels of the histogram bins with the maximum number of hits in the upper and lower regions of the waveform. The upper and lower regions of the waveform include the upper and lower 40%, respectively, of the peak-to-peak range of the waveform.
    peak Searches the entire waveform for its maximum and minimum levels.
    auto select Determines whether the histogram bins that correspond to the high and low state levels each have over 5% of the total hits. If so, this node returns those results. Otherwise, this node uses the peak method. This ensures a reasonable answer for either a square wave (ignoring the overshoot and undershoot) or a triangle wave (where a histogram fails).

    Default: auto select

    datatype_icon

    histogram size

    Number of bins in the histogram this node uses to determine the high and low state levels of the waveform.

    If you select the peak method, this node ignores this input.

    Default: 256

    datatype_icon

    histogram method

    Method this node uses to compute the histogram. Currently, mode is the only available histogram method.

    Name Description
    mode Uses the mode method.
    datatype_icon

    reserved

    Value reserved for future use.

    datatype_icon

    slope

    The rate of change of the signal in a transition region between high reference level and low reference level.

    This output can return a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

    The following equation defines slope:

    slope = high reference level low reference level transition duration
    datatype_icon

    transition duration

    Time span, in seconds, of the transition.

    This output can return a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

    A rising polarity transition duration is known as rise time, and a falling polarity transition duration is known as fall time, as shown in the following figure:

    datatype_icon

    pre-transition: undershoot

    Height of the local minimum preceding a rising or falling transition, which depends on the polarity you specify. Undershoot measures the height as a percentage of the histogram-based amplitude of the signal.

    This output can return a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

    datatype_icon

    pre-transition: overshoot

    Height of the local maximum preceding a rising or falling transition, which depends on the polarity you specify. Overshoot measures the height as a percentage of the histogram-based amplitude of the signal.

    This output can return a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

    datatype_icon

    post-transition: undershoot

    Height of the local minimum following a rising or falling transition, which depends on the polarity you specify. Undershoot measures the height as a percentage of the histogram-based amplitude of the signal.

    This output can return a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

    datatype_icon

    post-transition: overshoot

    Height of the local maximum following a rising or falling transition, which depends on the polarity you specify. Overshoot measures the height as a percentage of the histogram-based amplitude of the signal.

    This output can return a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

    datatype_icon

    error out

    Error information.

    The node produces this output according to standard error behavior.

    Standard Error Behavior

    Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

    error in does not contain an error error in contains an error
    If no error occurred before the node runs, the node begins execution normally.

    If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

    If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.
    datatype_icon

    measurement info

    Transition interval end points and the absolute reference levels used to define the transition.

    This output can return a cluster or a 1D array of clusters.

    datatype_icon

    start time

    Time of the rising low reference level crossing or falling high reference level crossing that defines the start of the transition to be measured.

    datatype_icon

    end time

    Time of the rising high reference level crossing or falling low reference level crossing that defines the end of the transition to be measured.

    datatype_icon

    ref levels

    Three user-defined reference levels of the waveform in absolute units.

    datatype_icon

    high ref level

    The high reference level.

    datatype_icon

    mid ref level

    The middle reference level.

    datatype_icon

    low ref level

    The low reference level.

    datatype_icon

    ref units

    Units of the reference levels.

    ref units is always absolute in measurement info.

    How polarity Affects Undershoot and Overshoot

    The following illustration shows the undershoot and overshoot when polarity is Rising.

    The following illustration shows the undershoot and overshoot when polarity is Falling.

    Algorithm for Calculating Pre-transition Outputs

    This node calculates pre-transition: undershoot and pre-transition: overshoot according to the following table.

    polarity pre-transition: undershoot pre-transition: overshoot
    Rising 100 * ( low state level local minimum amplitude ) 100 * ( local maximum low state level amplitude )
    Falling 100 * ( high state level local minimum amplitude ) 100 * ( local maximum high state level amplitude )

    To calculate pre-transition: undershoot and pre-transition: overshoot, this node searches for a local minimum and local maximum in the pre-transition aberration region immediately preceding the beginning of the transition specified by edge number and polarity. The pre-transition aberration region is defined as the minimum of 3*(end time - start time) and (current transition start time - previous transition end time)/2. If the transition to measure is the first in the waveform, the interval is defined as the minimum of 3*(end time - start time) and (start time - beginning of the waveform). This node calculates the high state level, low state level, and amplitude from the input signal.

    Algorithm for Calculating Post-transition Outputs

    This node calculates post-transition: undershoot and post-transition: overshoot according to the following table.

    polarity post-transition: undershoot post-transition: overshoot
    Rising 100 * ( high state level local minimum amplitude ) 100 * ( local maximum high state level amplitude )
    Falling 100 * ( low state level local minimum amplitude ) 100 * ( local maximum low state level amplitude )

    To calculate post-transition: undershoot and post-transition: overshoot, this node searches for a local minimum and local maximum in the post-transition aberration region immediately following the end of the transition specified by edge number and polarity. The post-transition aberration region is defined as the minimum of 3*(end time - start time) and (next transition start time - current transition end time)/2. If the transition to measure is the last in the waveform, the interval is defined as the minimum of 3*(end time - start time) and (end of the waveform - end time). This node calculates the high state level, low state level, and amplitude from the input signal.

    Where This Node Can Run:

    Desktop OS: Windows

    FPGA: DAQExpress does not support FPGA devices


    Recently Viewed Topics