Siemens SINUMERIK 840DE Programming Manual page 352

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.
G462
If no intersection is possible between the last TRC block and a preceding block, a straight
line is inserted, on retraction with G462 (initial setting), at the end point of the last block with
tool radius compensation (the block is extended by its end tangent).
The search for the intersection is then identical to the procedure for G461.
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Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
Fundamentals