ST_FTR_IIRSpec

Configuration structure for the function block FB_FTR_IIRSpec.

Syntax

Definition:

TYPE ST_FTR_IIRSpec :
STRUCT
    eFilterName        : E_FTR_Name;
    eFilterType        : E_FTR_Type;
    nFilterOrder       : UDINT;
    fCutoff            : LREAL;
    fBandwidth         : LREAL;
    fPassBandRipple    : LREAL;
    fSamplingRate      : LREAL;
    nOversamples       : UDINT;
    nChannels          : UDINT;
    pInitialValues     : POINTER TO LREAL;
    nInitialValuesSize : UDINT;
END_STRUCT
END_TYPE

Parameters

Name	Type	Description
eFilterName	E_FTR_Name	Describes the filter implementation (Butterworth, Chebyshev, Bessel)
eFilterType	E_FTR_Type	Describes the filter type (high-pass, low-pass, …)
nFilterOrder	UDINT	Filter order (max. 20 for high-pass and low-pass, max. 10 for band-pass and band-stop)
fCutoff	LREAL	Cut-off frequency in Hz (greater than 0 and less than fSamplingRate/2)
fBandwidth	LREAL	Bandwidth in Hz with respect to band-pass and band-stop.
fPassbandRipple	LREAL	Passband ripple of the amplitude response in the passband of the filter in dB (greater than 0)
fSamplingRate	LREAL	Sampling rate f_s in Hz
nOversamples	UDINT	Number of oversamples (greater than zero)
nChannels	UDINT	Number of channels (greater than zero and less than 101)
pInitialValues	Pointer to LREAL	Pointer to array with initial values (optional)
nInitialValuesSize	UDINT	Size of the array with initial values in BYTE (optional)

Notes on the influence of the parameters on the Butterworth, Chebyshev and Bessel type filters can be found here: Filter types and parameterization.