Beckhoff EPI4 Series, Documentation

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Commissioning and configuration
EPI4xxx, ERI4xxx 64 Version: 1.6
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.
Fig. 50: typ. attenuation curve notch.filter at 50 Hz
Filter data FIR filter (1- to 4-channel modules)
Filter Attenuation Limit frequency (-3 dB) Conversion time
50 Hz FIR > 50 dB 22 Hz 625 µs
60 Hz FIR > 45 dB 26 Hz 521 µs
• 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
IIR filter ~3 dB limit frequency at 500 µs sampling time
IIR 1 400 Hz
IIR 2 220 Hz
IIR 3 100 Hz
IIR 4 50 Hz
IIR 5 24 Hz
IIR 6 12 Hz
IIR 7 6.2 Hz
IIR 8 3.0 Hz