Siemens Sinumerik 840D sl Programming Manual page 283

Since an intersection exists only between the offset curves of the two blocks N10 and N40,
the two blocks N20 and N30 would have to be omitted. In the example, the control does not
know in block N40 if N10 has to be completely processed. Only a single block can therefore
be omitted.
With active CDOF2, the compensation motion shown in the figure is executed and not stopped.
In this situation, an active CDOF or CDON would result in an alarm.
Further information
Program test
To avoid program stops, the tool with the largest radius from the range of used tools should
always be used during the program test.
Examples of compensation motions for critical machining situations
The following examples show critical machining situations that are detected by the control and
compensated through modified tool paths. In all examples, a tool with too large a radius has
been used for the machining of the contour.
Example 1: Bottleneck detection
As the tool radius selected for the machining of this inside contour is too large, the "bottleneck"
is bypassed.
An alarm is output.
Fundamentals
Programming Manual, 01/2015, 6FC5398-1BP40-5BA2
11.5 Collision detection (CDON, CDOF, CDOF2)
Tool radius compensation
283