Siemens SINUMERIK Series Function Manual page 358

M1: Kinematic transformation
6.2 TRANSMIT face end transformation (option)
In the case of a contour that would require the pole to be traversed along the tool center
point path, the following three steps are taken to prevent the linear axis from traversing in
ranges beyond the turning center:
Step
1
2
3
In JOG mode, the motion stops in the pole. In this mode, the axis may exit from the pole only
along the path tangent on which it approached the pole. All other motion instructions would
require a step change in the rotary axis position or a large machine motion in the cases of
minimum motion instructions. They are rejected with alarm 21619.
Traversal close to pole
If a tool center point traverses past the pole, the control system automatically reduces the
feedrate and path acceleration rate such that the settings of the machine axes (MD 32000
$MA_MAX_AX_VELO[AX*] and MD32300 $MA_ MAX_AX_ACCEL[AX*]) are not exceeded.
The closer the path is to the pole, the greater the reduction in the feedrate.
Tool center point path with corner in pole
A tool center point path which includes a corner in the pole will not only cause a step change
in axis velocities, but also a step change in the rotary axis position. These cannot be reduced
by decelerating.
Figure 6-4
358
Action
Linear axis traverses into pole
Rotary axis turns through 180°, the other axes involved in the transformation
remain stationary.
Execution of remaining block. The linear axis now exits from the pole again.
Pole traversal
Function Manual, 03/2013, 6FC5397-1BP40-3BA1
Extended Functions