Limit Axis CNC Jerk using SMC_Polynomial_AbsMaxLocs

2026-05-22
2 days ago
  • josepmariarams - 2026-05-22

    Dears.

    Until now, I have been using CNC libraries with Codesys 3.5SP11. I was using SMC_Polynomial_AbsMaxLocs function, from CNC library, to calculate the axis jerks, interpolating splines, to limit it.

    Now I have passed to SP20, and the functions which calculates the zeros and the maximum-minimum and zeros of polynomials has been disapeared.

    Questions:

    -Exist any FB wich can limit the jerk of individual axis in CNC?
    -Exist any other functions which can calculate max-min and zeros of polynomials?

    Thanks

     
  • gseidel - 2 days ago

    Dear josepmariarams,

    this (internal) function has been removed with SoftMotion 4.17.0.0. We do not have public functions to compute the extrema of a polynomial.

    On which polynomials exactly did you call SMC_Polynomial_AbsMaxLocs? (Maybe if I understand better how you limit the jerk I can come up with an alternative.)

    There is no functionality to limit the jerk of individual axes in the CNC. With SMC_LimitDynamics, you can limit the velocity and acceleration of cartesian (X/Y/Z) and additional (P/Q/U/V/W/A/B/C) axes, but not the jerk. And with a quadratic ramp type you can limit the jerk on the path.

    Best regards,

    Georg

     

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