Overview

The TwinCAT 3 function TF3680 TC3 Filter provides various function blocks for implementing digital filters in a PLC library. Digital filters are used to manipulate digitalized (time-discrete and value-quantized) signals and to emphasize or suppress certain components of a signal in the frequency range, for example.

Applications:

Suppression of frequency bands, in which the wanted signal plays a subordinate role compared to the noise signal. One example is the conventional low-pass filter for suppressing high-frequency noise.
Targeted elimination of interfering frequency components. An example is a 50 Hz signal that is superimposed on the wanted signal, which influences the measuring signal through electromagnetic coupling of the mains voltage.

Function blocks:

Function block	Filter
FB_FTR_IIRCoeff FB_FTR_IIRSos	Enables the implementation of a custom filter through the specification of filter coefficients, so that, in principle, any filter characteristics can be used.
FB_FTR_IIRSpec	Enables the implementation of a filter of type "Butterworth", "Chebyshev" or "Bessel".
FB_FTR_PT1 FB_FTR_PT2 FB_FTR_PT3 FB_FTR_PTn FB_FTR_PT2oscillation FB_FTR_LeadLag FB_PTt	Enables the implementation of different delay elements of different order.
FB_FTR_MovAvg	Enables the implementation of a moving average filter for smoothing.
FB_FTR_Median	Median filter for smoothing signals with outliers.
FB_FTR_Notch	Enables the implementation of a band-stop filter to suppress a narrow frequency band.
FB_FTR_AcutalValue	Filter for the treatment of outliers.
FB_FTR_Gaussian	Smoothing filter with minimal group delay.