Siemens SINUMERIK 808D ADVANCED Programming And Operating Manual page 166

See the following illustration for contour definition:
If a tool radius compensation is programmed in the contour subroutine with G41/G42, the cycle is canceled, and alarm
10931 "Faulty cutting contour" is issued.
contour direction
The direction in which the stock removal contour is programmed can be freely selected. In the cycle, the machining direction
is defined automatically. In complete machining, the contour is finished in the same direction as machining was carried out
when roughing.
When deciding on the machining direction, the first and the last programmed contour points are taken into account.
Therefore, both coordinates must always be programmed in the first block of the contour subroutine.
Contour monitoring
The cycle provides contour monitoring with regard to the following:
● Clearance angle of the active tool
● Circular programming of arcs with an arc angle > 180 degrees
With relief cut elements, the cycle checks whether the machining is possible using the active tool. If the cycle detects that
this machining will result in a contour violation, it will be aborted after alarm 61604 "Active tool violates programmed contour"
has been output.
If the tool clearance angle is specified with zero in the tool compensation, this monitoring will not be performed.
If too large arcs are found in the compensation, alarm 10931 "Incorrect machining contour" appears.
Overhanging contours cannot be machined by CYCLE95. Contours of this type are not monitored by the cycle and
consequently there is no alarm.
Programming and Operating Manual (Turning)
166
6FC5398-5DP10-0BA2, 06/2015