CD Nyquist VI

Control Design VI and Function

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CD Nyquist VI

Owning Palette: Frequency Response VIs

Installed With: Control Design and Simulation Module

Produces the Nyquist plot of the input system for which this VI plots the imaginary part of the frequency response against its real part. You can display this data in the CD Nyquist Plot indicator. The data types you wire to the State-Space Model and Frequency Info inputs determine the polymorphic instance to use.

This VI converts state-space and zero-pole-gain models into transfer function models before determining the frequency response.

Details  

Use the pull-down menu to select an instance of this VI.

 Place on the block diagram  Find on the Functions palette

CD Nyquist (Frequency Range, State-Space)

Nyquist Graph Reference is a reference to the Nyquist Plot on an XY graph. Nyquist Graph Reference configures the x-scale, y-scale, and legend properties. If you want to use the default settings or customize the settings for these properties, do not wire a value to this input.
State-Space Model contains a mathematical representation of and information about the system for which this VI produces a Nyquist plot.
Frequency Range contains the frequency information of the model.
Initial frequency is the minimum frequency this VI uses in calculating the frequency response and producing the plots. The default is –1.
Final frequency is the maximum frequency this VI uses in calculating the frequency response and producing the plots. The default is –1.
Minimum number of points is the minimum number of points this VI uses in calculating the frequency response and producing the plots. The default is 100 points.
Frequency Unit specifies the units of frequency, either in Hertz or radians/seconds, to use in calculating the frequency response and producing the plots.

0Hz
1rad/s (default)
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. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it 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 exception control to treat what is normally an error as no error or to treat a warning as an error. 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.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
Plots Index is an array of clusters of the following two elements.
input # is the index number of the specific input to the system. This VI displays the response to this input in the Nyquist Plot on an XY graph. The index is zero-based.
output # is the index number of the specific output of the system that this VI displays in the Nyquist Plot on an XY graph. The index is zero-based.
Nyquist Plot returns the imaginary part of the complex frequency response of the input system this VI plots against its real part. The Plots Index input determines which plots to display on the XY graph. Right-click this terminal on the block diagram and select Create»Indicator from the shortcut menu to display this data in a CD Nyquist Plot indicator.
Nyquist Data returns information about the Nyquist plot data. To access the Nyquist Data, use the CD Get Frequency Response Data VI.
Frequency is a 1D-array of frequency values at which this VI calculates the magnitude and phase.
Real returns data about the frequency response of the real part of the elements in the matrix H(w). The ith column in the nth page of the array is the real part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are real parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
Imaginary returns data about the frequency response of the imaginary part of the elements in the matrix H(w). The ith column in the nth page of the array is the imaginary part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are imaginary parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
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, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

CD Nyquist (Frequency Range, Transfer Function)

Nyquist Graph Reference is a reference to the Nyquist Plot on an XY graph. Nyquist Graph Reference configures the x-scale, y-scale, and legend properties. If you want to use the default settings or customize the settings for these properties, do not wire a value to this input.
Transfer Function Model contains a mathematical representation of and information about the system for which this VI produces a Nyquist plot.
Frequency Range contains the frequency information of the model.
Initial frequency is the minimum frequency this VI uses in calculating the frequency response and producing the plots. The default is –1.
Final frequency is the maximum frequency this VI uses in calculating the frequency response and producing the plots. The default is –1.
Minimum number of points is the minimum number of points this VI uses in calculating the frequency response and producing the plots. The default is 100 points.
Frequency Unit specifies the units of frequency, either in Hertz or radians/seconds, to use in calculating the frequency response and producing the plots.

0Hz
1rad/s (default)
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. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it 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 exception control to treat what is normally an error as no error or to treat a warning as an error. 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.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
Plots Index is an array of clusters of the following two elements.
input # is the index number of the specific input to the system. This VI displays the response to this input in the Nyquist Plot on an XY graph. The index is zero-based.
output # is the index number of the specific output of the system that this VI displays in the Nyquist Plot on an XY graph. The index is zero-based.
Nyquist Plot returns the imaginary part of the complex frequency response of the input system this VI plots against its real part. The Plots Index input determines which plots to display on the XY graph. Right-click this terminal on the block diagram and select Create»Indicator from the shortcut menu to display this data in a CD Nyquist Plot indicator.
Nyquist Data returns information about the Nyquist plot data. To access the Nyquist Data, use the CD Get Frequency Response Data VI.
Frequency is a 1D-array of frequency values at which this VI calculates the magnitude and phase.
Real returns data about the frequency response of the real part of the elements in the matrix H(w). The ith column in the nth page of the array is the real part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are real parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
Imaginary returns data about the frequency response of the imaginary part of the elements in the matrix H(w). The ith column in the nth page of the array is the imaginary part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are imaginary parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
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, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

CD Nyquist (Frequency Range, Zero-Pole-Gain)

Nyquist Graph Reference is a reference to the Nyquist Plot on an XY graph. Nyquist Graph Reference configures the x-scale, y-scale, and legend properties. If you want to use the default settings or customize the settings for these properties, do not wire a value to this input.
Zero-Pole-Gain Model contains a mathematical representation of and information about the system for which this VI produces a Nyquist plot.
Frequency Range contains the frequency information of the model.
Initial frequency is the minimum frequency this VI uses in calculating the frequency response and producing the plots. The default is –1.
Final frequency is the maximum frequency this VI uses in calculating the frequency response and producing the plots. The default is –1.
Minimum number of points is the minimum number of points this VI uses in calculating the frequency response and producing the plots. The default is 100 points.
Frequency Unit specifies the units of frequency, either in Hertz or radians/seconds, to use in calculating the frequency response and producing the plots.

0Hz
1rad/s (default)
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. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it 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 exception control to treat what is normally an error as no error or to treat a warning as an error. 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.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
Plots Index is an array of clusters of the following two elements.
input # is the index number of the specific input to the system. This VI displays the response to this input in the Nyquist Plot on an XY graph. The index is zero-based.
output # is the index number of the specific output of the system that this VI displays in the Nyquist Plot on an XY graph. The index is zero-based.
Nyquist Plot returns the imaginary part of the complex frequency response of the input system this VI plots against its real part. The Plots Index input determines which plots to display on the XY graph. Right-click this terminal on the block diagram and select Create»Indicator from the shortcut menu to display this data in a CD Nyquist Plot indicator.
Nyquist Data returns information about the Nyquist plot data. To access the Nyquist Data, use the CD Get Frequency Response Data VI.
Frequency is a 1D-array of frequency values at which this VI calculates the magnitude and phase.
Real returns data about the frequency response of the real part of the elements in the matrix H(w). The ith column in the nth page of the array is the real part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are real parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
Imaginary returns data about the frequency response of the imaginary part of the elements in the matrix H(w). The ith column in the nth page of the array is the imaginary part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are imaginary parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
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, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

CD Nyquist (Frequency Vector, State-Space)

Nyquist Graph Reference is a reference to the Nyquist Plot on an XY graph. Nyquist Graph Reference configures the x-scale, y-scale, and legend properties. If you want to use the default settings or customize the settings for these properties, do not wire a value to this input.
State-Space Model contains a mathematical representation of and information about the system for which this VI produces a Nyquist plot.
Frequency Vector specifies information about the frequencies this VI uses to excite the model.
Frequency specifies the frequencies this VI uses to excite the model.
Frequency Unit specifies the unit of measurement of the Frequency array.

0Hz—Specifies that the frequency is measured in hertz.
1rad/s (default)—Specifies that the frequency is measured in radians per second.
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. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it 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 exception control to treat what is normally an error as no error or to treat a warning as an error. 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.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
Plots Index is an array of clusters of the following two elements.
input # is the index number of the specific input to the system. This VI displays the response to this input in the Nyquist Plot on an XY graph. The index is zero-based.
output # is the index number of the specific output of the system that this VI displays in the Nyquist Plot on an XY graph. The index is zero-based.
Nyquist Plot returns the imaginary part of the complex frequency response of the input system this VI plots against its real part. The Plots Index input determines which plots to display on the XY graph. Right-click this terminal on the block diagram and select Create»Indicator from the shortcut menu to display this data in a CD Nyquist Plot indicator.
Nyquist Data returns information about the Nyquist plot data. To access the Nyquist Data, use the CD Get Frequency Response Data VI.
Frequency is a 1D-array of frequency values at which this VI calculates the magnitude and phase.
Real returns data about the frequency response of the real part of the elements in the matrix H(w). The ith column in the nth page of the array is the real part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are real parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
Imaginary returns data about the frequency response of the imaginary part of the elements in the matrix H(w). The ith column in the nth page of the array is the imaginary part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are imaginary parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
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, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

CD Nyquist (Frequency Vector, Transfer Function)

Nyquist Graph Reference is a reference to the Nyquist Plot on an XY graph. Nyquist Graph Reference configures the x-scale, y-scale, and legend properties. If you want to use the default settings or customize the settings for these properties, do not wire a value to this input.
Transfer Function Model contains a mathematical representation of and information about the system for which this VI produces a Nyquist plot.
Frequency Vector specifies information about the frequencies this VI uses to excite the model.
Frequency specifies the frequencies this VI uses to excite the model.
Frequency Unit specifies the unit of measurement of the Frequency array.

0Hz—Specifies that the frequency is measured in hertz.
1rad/s (default)—Specifies that the frequency is measured in radians per second.
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. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it 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 exception control to treat what is normally an error as no error or to treat a warning as an error. 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.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
Plots Index is an array of clusters of the following two elements.
input # is the index number of the specific input to the system. This VI displays the response to this input in the Nyquist Plot on an XY graph. The index is zero-based.
output # is the index number of the specific output of the system that this VI displays in the Nyquist Plot on an XY graph. The index is zero-based.
Nyquist Plot returns the imaginary part of the complex frequency response of the input system this VI plots against its real part. The Plots Index input determines which plots to display on the XY graph. Right-click this terminal on the block diagram and select Create»Indicator from the shortcut menu to display this data in a CD Nyquist Plot indicator.
Nyquist Data returns information about the Nyquist plot data. To access the Nyquist Data, use the CD Get Frequency Response Data VI.
Frequency is a 1D-array of frequency values at which this VI calculates the magnitude and phase.
Real returns data about the frequency response of the real part of the elements in the matrix H(w). The ith column in the nth page of the array is the real part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are real parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
Imaginary returns data about the frequency response of the imaginary part of the elements in the matrix H(w). The ith column in the nth page of the array is the imaginary part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are imaginary parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
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, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

CD Nyquist (Frequency Vector, Zero-Pole-Gain)

Nyquist Graph Reference is a reference to the Nyquist Plot on an XY graph. Nyquist Graph Reference configures the x-scale, y-scale, and legend properties. If you want to use the default settings or customize the settings for these properties, do not wire a value to this input.
Zero-Pole-Gain Model contains a mathematical representation of and information about the system for which this VI produces a Nyquist plot.
Frequency Vector specifies information about the frequencies this VI uses to excite the model.
Frequency specifies the frequencies this VI uses to excite the model.
Frequency Unit specifies the unit of measurement of the Frequency array.

0Hz—Specifies that the frequency is measured in hertz.
1rad/s (default)—Specifies that the frequency is measured in radians per second.
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. This VI or function runs normally only if no error occurred before this VI or function runs. If an error occurs while this VI or function runs, it 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 exception control to treat what is normally an error as no error or to treat a warning as an error. 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.
status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.
Plots Index is an array of clusters of the following two elements.
input # is the index number of the specific input to the system. This VI displays the response to this input in the Nyquist Plot on an XY graph. The index is zero-based.
output # is the index number of the specific output of the system that this VI displays in the Nyquist Plot on an XY graph. The index is zero-based.
Nyquist Plot returns the imaginary part of the complex frequency response of the input system this VI plots against its real part. The Plots Index input determines which plots to display on the XY graph. Right-click this terminal on the block diagram and select Create»Indicator from the shortcut menu to display this data in a CD Nyquist Plot indicator.
Nyquist Data returns information about the Nyquist plot data. To access the Nyquist Data, use the CD Get Frequency Response Data VI.
Frequency is a 1D-array of frequency values at which this VI calculates the magnitude and phase.
Real returns data about the frequency response of the real part of the elements in the matrix H(w). The ith column in the nth page of the array is the real part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are real parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
Imaginary returns data about the frequency response of the imaginary part of the elements in the matrix H(w). The ith column in the nth page of the array is the imaginary part of the frequency response of the transfer function between the ith output and the nth input. For example, the first two columns of the 0th page are imaginary parts of frequency response of transfer functions between outputs y0 and y1 and the first input u0.
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, it describes the error status that this VI or function produces. Right-click the error out front panel indicator and select Explain Error from the shortcut menu for more information about the error.
status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

CD Nyquist Details

This VI supports delays. Refer to the LabVIEW Control Design User Manual for more information about delays.

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