IIR filter
The EL7031-0030 features a digital filter with infinite impulse response (Infinite Impulse Response filter, IIR filter). The filter can be enabled and disabled via index 0x8030:06 Enable filter (for channel 1) and index 0x8040:06 Enable filter (for channel 2).
The filter with IIR characteristic is a time-discrete, linear, time-invariant filter, which can be set to 8 levels via index 0x8030:15 Filter settings (for channel 1) and index 0x8040:15 Filter settings (for channel 2) (level 1 = weak recursive filter, level 8 = strong 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 1 ms.
Filter data for IIR filter
IIR filter | Limit frequency with internal terminal cycle time 1 ms (-3 dB) |
|---|---|
IIR 1 | 168 Hz |
IIR 2 | 88 Hz |
IIR 3 | 43 Hz |
IIR 4 | 21 Hz |
IIR 5 | 10.5 Hz |
IIR 6 | 5.2 Hz |
IIR 7 | 2.5 Hz |
IIR 8 | 1.2 Hz |
The typical conversion time and trigger mode depend on
- the selected filter setting
- the setting in CoE register index 0x1C33:01 Sync Mode
- by manual parameterization in the System Manager.
ATTENTION: Enter any changes made in the StartUp list! - by the StartUp list as an automatic parameter download during the EtherCAT start phase.
ATTENTION: Entries are implemented only after activation of the configuration!
The conversion time is the interval during which the terminal provides a new measured value. A new measured value is displayed by toggling “TxPDO Toggle” (index 0x60n0:10).
 | Reinitialization when the filter characteristic changes The filter is reinitialized when the characteristic changes. As a result, the output value is set to 0 directly after the change and then converges towards the applied analog value with the selected filter characteristic. |