Frequency Response VIs
- Updated2023-03-14
- 3 minute(s) read
Owning Palette: Control Design VIs and Functions
Requires: Control Design and Simulation Module. This topic might not match its corresponding palette in LabVIEW depending on your operating system, licensed product(s), and target.
Use the Frequency Response VIs to analyze a system model in the frequency domain.
The VIs on this palette can return general LabVIEW error codes or specific control design error codes.
| Palette Object | Description |
|---|---|
| CD All Margins | 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. Wire data to the State-Space Model and Frequency Range inputs determine the polymorphic instance to use or manually select the instance. |
| CD Bandwidth | Calculates the frequency, relative to the DC gain, at which the magnitude of the frequency response drops below Magnitude Drop (dB). You can use the CD Bandwidth VI only with single-input single-output (SISO) systems. Wire data to the State-Space Model input to determine the polymorphic instance to use or manually select the instance. |
| CD Bode | Produces the Bode magnitude and Bode phase plots of the system model on an XY graph. Wire data to the State-Space Model and Frequency Range inputs to determine the polymorphic instance to use or manually select the instance. |
| CD Evaluate at Frequency | Determines the magnitude and phase of the system at the given frequency. Wire data to the State-Space Model input to determine the polymorphic instance to use or manually select the instance. |
| CD Gain and Phase Margin | Calculates the gain and phase margins. If a system has multiple crossover frequencies, the CD Gain and Phase Margin VI returns the smallest gain and phase margins. You can use the CD Gain and Phase Margin VI only with single-input single-output (SISO) systems. Wire data to the State-Space Model and Frequency Range inputs to determine the polymorphic instance to use or manually select the instance. |
| CD Get Frequency from Frequency Data | Gets the frequency of a system at a specific point by searching Frequency Data for specific values. This VI determines the frequency using Magnitude and Phase for Bode plots, Real and Imaginary for Nyquist plots, and Open Loop Gain and Open Loop Phase for Nichols plots. This VI is especially useful for Nyquist and Nichols plots, where frequency is not obvious, but rather implicit in the plot. |
| CD Get Frequency Response Data | Gives access to the frequency response information the Frequency Response VIs return. The data types you wire to the Input and Output inputs determine the polymorphic instance to use. To get the frequency response data from all input-output pairs, you must manually select the polymorphic instance to use. |
| CD Nichols | Creates a Nichols plot of the input system for which this VI plots the magnitude, in decibels, of the frequency response against the phase. You can display this data in the CD Nichols Plot indicator. Wire data to the State-Space Model and Frequency Range inputs to determine the polymorphic instance to use or manually select the instance.
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| CD Nyquist | 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. Wire data to the State-Space Model and Frequency Range inputs to determine the polymorphic instance to use or manually select the instance.
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| CD Singular Values | Calculates the singular values of the frequency response of the input model. Wire data to the State-Space Model and Frequency Range inputs to determine the polymorphic instance to use or manually select the instance. |