IIR Filter

The EM37xx terminals are equipped with a digital filter that has the characteristics of an infinite impulse response filter (IIR filter).

The filter of IIR characteristics is a time-discrete, linear, time-invariant filter that can be set to 8 levels via index 0x8000:15 (level 1 = slightly recursive filter, up to level 8 = strongly recursive filter).

The IIR can be understood to be a moving average value calculation after a low-pass filter.

Due to the FreeRun synchronization mode, the IIR filter operates with an internal cycle time of 500 µs.

The EM37xx filter is activated or deactivated via CoE index 0x8000:06 (default: 1).

The filter characteristics are set via index 0x8000:15 The filter frequencies are set for all channels of the EM37xx terminals centrally via index 0x8000:15 (channel 1). The corresponding indices 0x80n0:15 of the other channels have no parameterization function! The latest firmware version (see status table) returns an EtherCAT-compliant error message, if the filter characteristics of other channels (index 0x80n0:06, 0x80n0:15) are set.

Filter data for IIR filter