Siemens SINUMERIK 828D Function Manual page 1484

W1: Tool offset
18.5 Tool radius compensation 2D (TRC)
Predictive contour calculation
If no intersection is found between two consecutive blocks, the control automatically checks the next block and
attempts to find an intersection with the equidistant paths of this block (see figure below: intersection S). This
automatic check of the next block (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 check, program execution is interrupted and
an alarm is output.
Figure 18-29 If there is no intersection between N30 and block N40, the intersection between block N30 and block N50 is
calculated.
Multiple intersections
→ see also "Collision detection"
It can be the case with inside corners that predictive contour calculation finds multiple intersections of the
equidistant paths in several consecutive blocks. In these cases, the last intersection is always used as the valid
intersection:
Basic Functions
1484
Function Manual, 09/2011, 6FC5397-0BP40-2BA0