Filter mode (FIR and IIR), Index 0x0800:06, 0x0800:15

The EPI31xx, ERI31xx and EPI4xxx, ERI4xxx modules are equipped with a digital filter, which, depending on the setting, can assume the characteristics of:

• a filter with finite impulse response (Finite Impulse Response Filter, FIR filter) or
• a filter with infinite impulse response (Infinite Impulse Response Filter, IIR filter).

The filter is deactivated by default. Please observe the following note regarding activation with index 0x0800:06.

Activation of the filter with index 0x0800:06 and setting of the filter characteristics via index 0x0800:15 The filter frequencies are set centrally for all channels of the EPI3xxx, ERI31xx / EPI4xxx, ERI4xxx modules via index 0x0800:15 (channel 1).

• FIR filter
  The filter works as a notch filter and determines the conversion time of the module. It is parameterized via index 0x0800:15. The higher the filter frequency, the faster the conversion time. A 50 Hz and a 60 Hz filter are available.
  Notch filter means that the filter has zeros (notches) in the frequency response at the filter frequency and multiples thereof, i.e. it attenuates the amplitude at these frequencies.
  The FIR filter operates as a non-recursive filter.

• IIR filter
  The filter with IIR characteristics is a discrete time, linear, time invariant filter that can be set to eight levels (level 1 = weak recursive filter, up to level 8 = strong recursive filter).
  The IIR can be understood to be a moving average value calculation after a low-pass filter.
  Filter characteristics for IIR filters