Siemens SINUMERIK 840D sl Function Manual page 475

The response is different for PTPG0. Here, with active TRC, an internal switchover to CP takes
place so that the TRC is performed correctly.
Smooth approach and retraction (SAR)
If PTP/PTPWOC is active, SAR cannot be used, because SAR needs a contour to design the
approach and retraction and to be able to approach or retract tangentially.
With PTPG0, on the other hand, SAR is possible because the blocks required for SAR are
traversed with CP. The G0 blocks up to the actual approach contour are executed with PTP
travel and therefore quickly. The same applies to the retract blocks.
Chipping cycles
With active PTP/PTPWOC, chipping cycles such as CONTPRON or CONTDCON cannot be
applied because the chipping require a contour to be able to construct the cut segmentation.
With PTPG0, on the other hand, chipping cycles are possible because the blocks required for
the chipping cycles are traversed with CP.
Chamfer and rounding
Chamfer and rounding are ignored during PTP travel.
Axis overlay
An axis superimposing in the interpolation may not change during the PTP sequence. This
applies, for example, to LIFTFAST, fine tool offset, coupled motion TRAILON and tangential
follow-up TANGON.
NC block compression
In the PTP blocks, an active compressor function (COMPON, COMPCURV, COMPCAD or
COMPSURF) is automatically deselected.
Blending
Blending with G643 is not possible with the PTP travel. In the PTP blocks with an active G643,
there is an automatic switchover to G642.
In addition, the following special features should be noted:
● Blending is always done in the machine coordinate system and it thus high-performance
in terms of time. The criteria for G642 is always interpreted in the machine coordinate
system and not as usual in the Cartesian basic coordinate system.
● Smoothing G641 is determined as a function of the fictitious path calculated from the
machine axis coordinates.
Extended Functions
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
M1: Kinematic transformation
7.6 Cartesian PTP travel
475