SI Bode Plot VI

Owning Palette: Model Analysis VIs

Requires: Advanced Signal Processing Toolkit or Control Design and Simulation Module

Produces the Bode magnitude and Bode phase plots of the system model on an XY graph.

Details  Examples

	freq info specifies the frequency information for the data plot. start frequency specifies the start frequency of the data plot. The value of start frequency must be in a normalized frequency range of 0–0.5 times the real sampling rate. end frequency specifies the end frequency of the data plot. The value of end frequency must be in a normalized frequency range of 0–0.5 times the real sampling rate and greater than the value of start frequency. num of freq bins specifies the number of frequency bins between start frequency and end frequency for the data plot. interval type determines how the frequency points of the FRF increase from start frequency to end frequency. For a logarithmic interval type, the frequency points are the following: f0, f0*df, f0*(df)2, f0*(df)3, ..., fFinal where f0 = start frequency fFinal = end frequency df = (log10(end frequency) – log10(start frequency)) / (num of freq bins – 1) For a linear interval type, the frequency points are the following: f0, f0+df, f0+2df, f0+3df, ..., fFinal where f0 = start frequency fFinal = end frequency df = (end frequency – start frequency) / (num of freq bins – 1) 0 logarithmic (default) 1 linear
	system model contains information about the model structure, nominal or estimated parameters, identification result, and so on. Use the Model Management VIs to retrieve the information system model contains. Note  You can use a customized system model probe to view model information that flows through system model wires when you debug a block diagram created with the System Identification VIs. Right-click a system model wire and select Custom Probe»SI System Model from the shortcut menu to use the system model probe.
	channel selects the signal pair with which to compute the transfer function. type specifies whether to compute the transfer function between a stimulus signal and a response signal or the transfer function between a noise signal and a response signal. 0 stimulus (default)—Computes the transfer function between a stimulus signal and a response signal. Use input index and output index to select the stimulus and response signals to use. 1 noise—Computes the transfer function between a noise signal and a response signal. Use input index and output index to select the noise and response signals to use. input index specifies the index of the system input channel with which to compute the transfer function. input index applies only for MISO or MIMO system models. output index specifies the index of the system output channel with which to compute the transfer function. output index applies only for MIMO system models.
	confidence level (%) specifies the percentage confidence interval for the FRF.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	magnitude unit specifies the type of scaling to use for the magnitude axis, or the y-axis. 0 dB (default) 1 linear
	show confidence range? specifies whether to show the confidence range of the plot data. The default is TRUE.
	Bode magnitude plot returns the Bode magnitude plot of the input signal. Bode magnitude plot is a plot on an XY graph that shows the linear or decibel magnitude of the given model plotted against a set of frequencies. Use the SI Bode Plot Indicator to display the Bode magnitude plot. frequency returns the frequency points for the Bode magnitude plot. magnitude returns the magnitude values of corresponding frequency points.
	Bode phase plot returns the Bode phase plot of the input signal. Bode phase plot is a plot on an XY graph that shows the phase, in degrees, of the model plotted against a set of frequency values. Use the SI Bode Plot Indicator to display the Bode phase plot. frequency returns the frequency points for the Bode phase plot. phase returns the phase values of corresponding frequency points.
	error out contains error information. This output provides standard error out functionality.

SI Bode Plot Details

This VI computes the transfer function and frequency response function (FRF) for one input-output pair of a system model. This VI then presents the FRF as Bode magnitude and Bode phase plots. Bode magnitude plots display magnitude versus frequency, and Bode phase plots display phase versus frequency. Use the SI Bode Plot Indicator to display the Bode plots on the front panel window.

Examples

Refer to the following VIs for examples of using the SI Bode Plot VI:

• Model Presentation VI: labview\examples\System Identification\Getting Started\General.llb
• Flexible Arm VI: labview\examples\System Identification\Industry Applications\Mechanical Systems.llb