Siemens SINUMERIK 840D sl Function Manual page 1880

Detailed Description
2.4 Tool radius compensation 2D (TRC)
G460
With G460, the approach/retraction strategy is the same as before.
G461
If no intersection is possible between the last TRC block and a preceding block, the offset
curve of this block is extended with a circle whose center point lies at the end point of the
uncorrected block and whose radius is equal to the tool radius.
Figure 2-40
The control attempts to cut this circle with one of the preceding blocks. If CDOF is active, the
search is terminated when an intersection is found, i.e., the system does not check for more
intersections with even earlier blocks.
If CDON is active, the search for more intersections continues after the first intersection is
found.
An intersection point, which is found in this way, is the new end point of a preceding block
and the start point of the deactivation block. The inserted circle is used exclusively to
calculate the intersection and does not produce a traversing movement.
Note
If no intersection is found, the following alarm is output:
Alarm "10751 Collision danger"
92
Retraction behavior with G461
Basic logic functions: Tool Offset (W1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0