Collision Detection (Cdon, Cdof, Cdof2) - Siemens Sinumerik 840D sl Programming Manual

If KONT is active (travel round contour at start or end point), the behavior differs according to
whether the end point is in front of or behind the contour.
● End point in front of contour
If the end point is in front of the contour, the retraction behavior is the same as with NORM.
This property does not change even if the last contour block for G451 is extended with a
straight line or a circle. Additional circumnavigation strategies to avoid a contour violation
in the vicinity of the contour end point are therefore not required.
● End point behind contour
If the end point is behind the contour, a circle or straight line is always inserted depending
on G450/G451. In this case, G460-462 has no effect. If the last traversing block in this
situation has no intersection with a preceding block, an intersection with the inserted contour
element or with the straight line of the end point of the bypass circle to the programmed
endpoint can result.
If the inserted contour element is a circle (G450), and this forms an interface with the
preceding block, this is equal to the interface that would occur with NORM and G461. In
general, however, a remaining section of the circle still has to be traversed. For the linear
part of the retraction block, no further calculation of intersection is required.
In the second case, if no interface of the inserted contour element with the preceding blocks
is found, the intersection between the retraction straight line and a preceding block is
traversed.
Therefore, a behavior that deviates from G460 can only occur with active G461 or G462
either if NORM is active or the behavior with KONT is geometrically identical to that with
NORM.
11.5

Collision detection (CDON, CDOF, CDOF2)

With the collision detection and active tool radius compensation, the tool paths are monitored
through look-ahead contour calculation. This look-ahead function allows possible collisions to
be detected in advance and permits the control to actively avoid them.
Collision detection can be activated or deactivated in the NC program.
Fundamentals
Programming Manual, 01/2015, 6FC5398-1BP40-5BA2
11.5 Collision detection (CDON, CDOF, CDOF2)
Tool radius compensation
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