Siemens SINUMERIK 840D sl Programming Manual page 236

Special motion commands
4.2 Spline interpolation (ASPLINE, BSPLINE, CSPLINE, BAUTO, BNAT, BTAN, EAUTO, ENAT, ETAN, PW,
SD, PL)
Further Information
Advantages of spline interpolation
By using spline interpolation, the following advantages can be obtained contrary to using
straight line blocks
● The number of part program blocks required to describe the contour are reduced
● Soft, curve characteristics that reduce the stress on the mechanical system at transitions
Properties and use of the various spline types
Spline type
A spline
236
:
G01
between part program blocks.
Properties and use
Properties:
The passes precisely through the specified intermediate points along the

curve.
The curve characteristic is tangential, but does not have continuous

curvature.
Produces hardly any undesirable oscillations.

The area of influence of changes to intermediate points along the curve is

local. This means that a change to an intermediate point along the curve only
affects up to max. 6 adjacent intermediate points.
Application:
The A spline is especially suitable for interpolating curves with large changes in
the gradient (e.g. staircase-type curves and characteristics).
Programming Manual, 03/2013, 6FC5398-2BP40-3BA1
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