CD All Margins VI

Control Design VI and Function

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CD All Margins VI

Owning Palette: Frequency Response VIs

Installed With: Control Design and Simulation Module

Calculates all the gain and phase margins, which result from the frequency response crossing at 0 decibels (magnitude) and –180 degrees (phase). You can use the CD All Margins VI only with single-input single-output (SISO) systems. You can use this polymorphic to calculate the gain and phase margins of state-space models, transfer function models, zero-pole-gain models, and stand-alone frequency response data. The data types you wire to the State-Space Model and Frequency Info inputs determine the polymorphic instance to use.

This VI converts the state-space and zero-pole-gain models into transfer function models before calculating their margins.

Details  

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

 Place on the block diagram  Find on the Functions palette

CD All Margins (State-Space)

State-Space Model contains a mathematical representation of and information about the system for which this VI determines gain and phase margins.
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)
Magnitude Scale specifies how to scale the magnitude of the frequency response.

0linear (default)—Does not convert the magnitude of the frequency response to decibels.
1db—Converts the magnitude of the frequency response to decibels.
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.
Gain Margins returns information about the gain margins.
G.M. Frequency lists all the frequencies at which the system phase crosses –180 degrees. The ith element of this array corresponds to the ith gain margin value in the Gain Margins array.
Gain Margins lists all the gain margins of the system.
Phase Margins returns information about the phase margins.
P.M. Frequency lists all the frequencies at which the system magnitude crosses 0 decibels. The ith element of this array corresponds to the ith phase margin value in the Phase Margins array.
Phase Margins lists all the phase margins of the system.
Frequency Response Data returns the data before this VI parameterizes it. To access the frequency response data, use the CD Get Frequency Response Data VI.
Frequency is a 1D-array of frequency values (in radians/seconds) at which this VI calculates the magnitude and phase.
Magnitude is a 1D-array. For continuous-time systems H(s), the ith element of the array is defined by the following equation:



For discrete-time systems, with sampling time T seconds, the ith element of the array is defined by the following equation:

Phase is a 1D-array. For continuous-time systems, the ith element is defined as:

For discrete-time systems, with sampling time T seconds, the ith element is defined as:

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 All Margins (Transfer Function)

Transfer Function Model contains a mathematical representation of and information about the system for which this VI determines gain and phase margins.
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)
Magnitude Scale specifies how to scale the magnitude of the frequency response.

0linear (default)—Does not convert the magnitude of the frequency response to decibels.
1db—Converts the magnitude of the frequency response to decibels.
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.
Gain Margins returns information about the gain margins.
G.M. Frequency lists all the frequencies at which the system phase crosses –180 degrees. The ith element of this array corresponds to the ith gain margin value in the Gain Margins array.
Gain Margins lists all the gain margins of the system.
Phase Margins returns information about the phase margins.
P.M. Frequency lists all the frequencies at which the system magnitude crosses 0 decibels. The ith element of this array corresponds to the ith phase margin value in the Phase Margins array.
Phase Margins lists all the phase margins of the system.
Frequency Response Data returns the data before this VI parameterizes it. To access the frequency response data, use the CD Get Frequency Response Data VI.
Frequency is a 1D-array of frequency values (in radians/seconds) at which this VI calculates the magnitude and phase.
Magnitude is a 1D-array. For continuous-time systems H(s), the ith element of the array is defined by the following equation:



For discrete-time systems, with sampling time T seconds, the ith element of the array is defined by the following equation:

Phase is a 1D-array. For continuous-time systems, the ith element is defined as:

For discrete-time systems, with sampling time T seconds, the ith element is defined as:

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 All Margins (Zero-Pole-Gain)

Zero-Pole-Gain Model contains a mathematical representation of and information about the system for which this VI determines gain and phase margins.
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)
Magnitude Scale specifies how to scale the magnitude of the frequency response.

0linear (default)—Does not convert the magnitude of the frequency response to decibels.
1db—Converts the magnitude of the frequency response to decibels.
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.
Gain Margins returns information about the gain margins.
G.M. Frequency lists all the frequencies at which the system phase crosses –180 degrees. The ith element of this array corresponds to the ith gain margin value in the Gain Margins array.
Gain Margins lists all the gain margins of the system.
Phase Margins returns information about the phase margins.
P.M. Frequency lists all the frequencies at which the system magnitude crosses 0 decibels. The ith element of this array corresponds to the ith phase margin value in the Phase Margins array.
Phase Margins lists all the phase margins of the system.
Frequency Response Data returns the data before this VI parameterizes it. To access the frequency response data, use the CD Get Frequency Response Data VI.
Frequency is a 1D-array of frequency values (in radians/seconds) at which this VI calculates the magnitude and phase.
Magnitude is a 1D-array. For continuous-time systems H(s), the ith element of the array is defined by the following equation:



For discrete-time systems, with sampling time T seconds, the ith element of the array is defined by the following equation:

Phase is a 1D-array. For continuous-time systems, the ith element is defined as:

For discrete-time systems, with sampling time T seconds, the ith element is defined as:

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 All Margins (Frequency Response Data)

Frequency Response specifies the frequency response for which this VI calculates the margins.
Magnitude specifies the magnitude component of the frequency response. The Magnitude Scale parameter defines the units of the Magnitude array.
Phase specifies the phase component, in degrees, of the frequency response.
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.
Magnitude Scale specifies how to scale the magnitude of the frequency response.

0linear (default)—Does not convert the magnitude of the frequency response to decibels.
1db—Converts the magnitude of the frequency response to decibels.
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.
Gain Margins returns information about the gain margins.
G.M. Frequency lists all the frequencies at which the system phase crosses –180 degrees. The ith element of this array corresponds to the ith gain margin value in the Gain Margins array.
Gain Margins lists all the gain margins of the system.
Phase Margins returns information about the phase margins.
P.M. Frequency lists all the frequencies at which the system magnitude crosses 0 decibels. The ith element of this array corresponds to the ith phase margin value in the Phase Margins array.
Phase Margins lists all the phase margins of the system.
Frequency Response Data returns the data before this VI parameterizes it. To access the frequency response data, use the CD Get Frequency Response Data VI.
Frequency is a 1D-array of frequency values (in radians/seconds) at which this VI calculates the magnitude and phase.
Magnitude is a 1D-array. For continuous-time systems H(s), the ith element of the array is defined by the following equation:



For discrete-time systems, with sampling time T seconds, the ith element of the array is defined by the following equation:

Phase is a 1D-array. For continuous-time systems, the ith element is defined as:

For discrete-time systems, with sampling time T seconds, the ith element is defined as:

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 All Margins Details

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

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