ST_CM_RealFFT_InitPars

Function block-specific structure with initialization parameters, which are analyzed when the function block is initialized.

TYPE ST_CM_RealFFT_InitPars EXTENDS ST_CM_Object_InitPars :
STRUCT
    nFFT_Length  : UDINT := 512;    (* Length of FFT. *)
    bForward     : BOOL := TRUE;    (* Flag indicating forward FFT. *)
    bHalfSpec    : BOOL := TRUE;    (* Flag indicating length of output; if TRUE, the algorithm outputs half the spectrum (nFFT_Length/2 + 1). *)
    nChannels    : UDINT := 1;      (* Number of channels. *)
END_STRUCT
END_TYPE

• nFFT_Length is the length of the FFT. It must be greater than one and an integral power of two.
• bForward is a Boolean parameter that specifies the direction of the FFT. If the value is TRUE, the normal FFT is calculated. Otherwise the inverse FFT is used.
• bHalfSpec is a Boolean parameter that specifies the size of the result buffer. If the value is TRUE, the algorithm outputs the half-spectrum (nFFT_Length/2 + 1).
• nChannels defines the number of independent channels. This must be greater than zero.