The software filter for the encoder inputs is available only for the iPOS family and the iMOTIONCUBE drive. It can be activated and programmed from the “Motor Setup” dialog.

The filter is a digital input qualifier algorithm that works as in the graph below.

The “GPIO Signal” is either of the encoder signals. The “Output From Qualifier ” is what reaches the motion control algorithm. You can see that when the encoder signal first switches from 1 to 0, the Output From Qualifier is not changed instantly, but the qualification process starts (this requires the encoder signal to remain unchanged for the number of samples defined when you programmed the filter. You can then see that the noise (marked with (A)) is rejected on the basis that it has a shorter period than the sampling period (or has a higher frequency than the limit frequency).

Returning to the settings from the “Motor Setup” dialog, the filter can be set to 1/3, 1/6, 1/12 …. 1/72. These values define how many “samples” are used for the qualification process.