Siemens SINUMERIK 840D sl Programming Manual page 237

4.2 Spline interpolation (ASPLINE, BSPLINE, CSPLINE, BAUTO, BNAT, BTAN, EAUTO, ENAT, ETAN, PW, SD, PL)
Spline type
B spline
Job Planning
Programming Manual, 03/2013, 6FC5398-2BP40-3BA1
Properties and use
Features:
Does not run through the specified intermediate points along the curve, but

only close to them. The intermediate points to not attract the curve. The
curve characteristic can be additionally influenced by weighting the
intermediate points using a factor.
The curve characteristic is tangential with continuous curvature.

Does not generate 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:
Their B spline is primarily intended as interface to CAD systems.
Special motion commands
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