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

Version:
Last Modified: August 28, 2017

Returns various measurements of a specific pulse in a periodic waveform or an array of periodic waveforms, such as the period, pulse duration, and duty cycle.

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signal

The input signal.

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

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polarity

Value that specifies whether this node measures high or low pulses.

Name Value Description
low pulse 0 Measures low pulses.
high pulse 1 Measures high pulses.

Default: low pulse

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pulse number

Number of the pulse that this node measures. For example, if pulse number is 1 and polarity is low pulse, the node returns the pulse duration of the first low pulse. The node measures the period and duty cycle of the period that begins with the (2n - 1)th mid reference level crossing, where n is pulse number.

Default: 1

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reference levels settings

High, middle, and low reference levels of a waveform.

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high ref level

High reference level of the waveform.

After the signal crosses the mid ref level in the rising direction, it must cross the high ref level before the next falling mid ref level crossing can be counted.

Default: 90

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mid ref level

Middle reference level of the waveform.

The interval between consecutive rising mid ref level crossings defines one cycle, or period, of the waveform. At least one high or low reference level crossing must separate each mid ref level crossing.

Default: 50

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low ref level

Low reference level of the waveform.

After the signal crosses the mid ref level in the falling direction, it must cross the low ref level before the next rising mid ref level crossing can be counted.

Default: 10

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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

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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

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state levels settings

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

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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

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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

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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.
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reserved

Value reserved for future use.

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period

Time between adjacent middle reference level crossings in the same direction in seconds.

The reciprocal of this value is the signal frequency. The measurement interval includes the pulse you specify in pulse number.

This output returns a double-precision, floating-point number or an array of double-precision, floating-point numbers.

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pulse duration

Time difference, in seconds, between the first two middle reference level crossings of the specified pulse number.

pulse duration is also known as pulse width.

This output returns a double-precision, floating-point number or an array of double-precision, floating-point numbers.

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duty cycle

Fraction of a period.

duty cycle is also known as duty factor.

This output returns a double-precision, floating-point number or an array of double-precision, floating-point numbers.

Equation for Calculating duty cycle

This node uses the following equation to calculate duty cycle:

dutycycle = 100 × ( pulseduration period )

In this equation, pulse duration can refer to the high or low portion of the period, depending on whether polarity is high pulse or low pulse.

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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.
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measurement info

Pulse-center time of the selected pulse and the absolute reference levels this node uses to define the measurement cycle.

This output can be a cluster or an array of clusters.

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pulse center

Time instant of the midpoint of the specified pulse number.

Algorithm Definition

pulse center for a polarity of high pulse is given by the following equation.

t c = t f t r 2

where tc is the pulse center time, tf is the time instant of the falling mid ref level crossing, and tr is the time instant of the preceding rising mid ref level crossing.

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ref levels

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

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high ref level

The high reference level.

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mid ref level

The middle reference level.

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low ref level

The low reference level.

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ref units

Units of the reference levels.

ref units is always absolute in measurement info.

Where This Node Can Run:

Desktop OS: Windows

FPGA: This product does not support FPGA devices

Web Server: Not supported in VIs that run in a web application


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