Siemens SINUMERIK 840Di Function Manual page 1746

Detailed Description
2.4 Tool: Tool radius compensation 2D (TRC)
If no intersection is found within the number of blocks defined for the check, program
execution is interrupted and an alarm is output.
Fig. 2-32
Multiple intersections
→ see also "Collision detection"
It can be the case with inside corners that multiple intersections of the equidistant paths are
found in several consecutive blocks. In these cases, the last intersection is always used as
the valid intersection (see figure below).
The maximum number of blocks used for the predictive check can be entered in machine
data:
MD20240 $MC_CUTCOM_MAXNUM_CHECK_BLOCKS
(blocks for predictive contour calculation with TRC).
2-66
If there is no intersection between N30 and block N40, the intersection between block
N30 and block N50 is calculated.
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
Tool Compensation (W1)