ST_FTR_IIRSos

Configuration structure for the function block FB_FTR_IIRSos.

Syntax

Definition:

TYPE ST_FTR_IIRSos :
STRUCT
    pCoefficientArrayAdr_Sos  : POINTER TO LREAL;
    nCoefficientArraySize_Sos : UDINT;
    bReset                    : BOOL := TRUE;
    nOversamples              : UDINT;
    nChannels                 : UDINT;
    pInitialValues            : POINTER TO LREAL;
    nInitialValuesSize        : UDINT;
END_STRUCT
END_TYPE

Parameter

Name	Type	Description
pCoefficientArrayAdr_Sos	Pointer to LREAL	Pointer to an array with filter coefficients [b₀₁, b₁₁, b₂₁,a₀₁, a₁₁, a₂₁, b₀₂, b₁₂, b₂₂,a₀₂, a₁₂, a₂₂, …. b_0M, b_1M, b_2M,a_0M, a_1M, a_2M]
nCoefficientArraySize_Sos	UDINT	Size of the array with filter coefficients in BYTES
bReset	BOOL	If TRUE, a reset is performed when the filter is configured. If FALSE, the historical values x[n-k] and y[n-k] are not reset.
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)

An example of a filter with 3 biquads might look like this:

aCoeffs_Sos : ARRAY [1..3] OF ARRAY [1..6] OF LREAL :=            
              [ [1, 1, 1, 1, 1, 1],   // [b01,b11,b21,a01,a11,a21] 
              [ [1, 1, 1, 1, 1, 1],   // [b02,b12,b22,a02,a12,a22] 
              [ [1, 1, 1, 1, 1, 1]];  // [b03,b13,b23,a03,a13,a23