Tolerance window for IIR axis filter after feedhold (P-AXIS-00780)


Tolerance window for stopping the IIR axis filter after feedhold


This parameter specifies the position tolerance within which the starting position of the IIR axis filter (infinite impulse response axis filter) is treated as “position reached”. The filter state is then more or less “frozen”.

In this state the following applies:

Abs(unfiltered command value - filtered command value) < P-AXIS-00780


The parameter is only effective in combination with feedhold.


The CNC ensures at the transition point that the maximum permissible axis acceleration is not exceeded.

When IIR axis filters are activated and feedhold is commanded, i.e. also at CNC reset, the system checks whether the tolerance window is reached and and if so, the filter state is “frozen”.



The existing position difference between filter output and filter input is then reduced when the axis makes its next movement.


If P-AXIS-00780 is assigned the value 0, the function is inactive.



Data type


Data range

0.01 <= P-AXIS-00780

Axis types

T, R


T: 0.1 µm

R: 0.0001°

Default value


Drive types



Possible application:

Depending on the parameterisation, certain filter types, e.g. band stops, tend to post-oscillate and this can lead to undesired axis movements.

For example, safety functions may disable drive release at a specific time after feedhold is commanded. If there are still movements after this time due to post-oscillating axis filters, the result may be axis-specific errors from the CNC.

Parameter available as of CNC Build V3.1.3079.17 or V3.1.3107.10.