Siemens SINUMERIK 840D sl Programming Manual page 602

Work preparation
3.7 Special motion commands
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 control needs a certain number of spline end-point blocks for every ten blocks:
Spline type
A spline:
B spline:
C spline:
Note
An alarm is output if the tolerated value is undershot and likewise when one of the axes involved
in the spline is programmed as a positioning axis.
Combine short spline blocks
Spline interpolation can result in short spline blocks, which reduce the path velocity
unnecessarily. The "Combine short spline blocks" function allows you to combine these blocks
such that the resulting block length is sufficient and does not reduce the path velocity.
602
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 to calculate the spline segment is entered in MD20160. The
default setting is 8%. At least 9 blocks out of every 10 must be spline blocks.
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming