Siemens SINUMERIK 840Di sl Programming Manual page 380

Tool offsets
8.11 Smooth approach and retraction
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.
The control attempts to cut this circle with one of the preceding blocks.
Retraction behavior with G461 (see example)
Collision monitoring CDON, CDOF
If CDOF is active (see section Collision monitoring, CDON, CDOF), the search is aborted
when an intersection is found, i.e., the system does not check whether further intersections
with previous blocks exist.
If CDON is active, the search continues for further intersections 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, alarm 10751 (collision danger) is output.
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Programming Manual, 11/2006, 6FC5398-1BP10-2BA0
Fundamentals