Siemens SINUMERIK 840D sl Programming Manual page 274

Special motion commands
4.2 Spline interpolation (ASPLINE, BSPLINE, CSPLINE, BAUTO, BNAT, BTAN, EAUTO, ENAT, ETAN, PW,
SD, PL)
Comparison of three spline types with identical interpolation points
Minimum number of spline blocks
The G codes ASPLINE, BSPLINE and CSPLINE link block end points with splines. For this
purpose, a series of blocks (end points) must be simultaneously calculated. The buffer size
for calculations is ten blocks as standard. Not every piece of block information is a spline end
point. However, the controller needs a certain number of spline end-point blocks for every 10
blocks:
Spline type
A spline:
B spline:
C spline:
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Minimum number of spline blocks
At least 4 blocks out of every 10 must be spline blocks.
These do not include comment blocks or parameter calculations.
At least 6 blocks out of every 10 must be spline blocks.
These do not include comment blocks or parameter calculations.
The required minimum number of spline blocks is the result of the following sum:
Value of MD20160 $MC_CUBIC_SPLINE_BLOCKS + 1
The number of points used to calculate the spline segment is entered in MD20160.
The default setting is 8. As standard, at least 9 blocks out of every 10 must be spline
blocks.
Programming Manual, 06/2009, 6FC5398-2BP20-0BA0
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