Siemens SINUMERIK 840D sl Function Manual page 75

No intersection
For inside corners, it is possible that no intersection is found between two consecutive blocks.
In this case, the control automatically checks the next block and attempts to find an intersection
with the equidistant paths of this block:
S:
Figure 2-20
This automatic check of the next blocks, predictive contour calculation, is always performed
until a number of blocks defined via machine data has been reached.
MD20240 $MC_CUTCOM_MAXNUM_CHECK_BLOCKS (blocks for predictive contour
calculation for TRC)
If no intersection is found within the number of blocks defined for the looking ahead, program
execution is interrupted and an alarm is output.
Tools
Function Manual, 06/2019, A5E47435126B AA
Point of intersection
Predictive contour calculation
W1: Tool offset
2.5 2D tool radius compensation
75