Siemens SINUMERIK 840D sl Programming Manual page 309

Example:
The target position shown in the diagram can be approached in the negative or positive
direction. The direction is programmed under address A1.
A1=225°, TU=Bit 0, → positive direction
A1=−135°, TU=Bit 1, → negative direction
Example of evaluation of TU for generic 5/6-axis transformation and target positions
Variable TU contains a bit, which indicates the traversing direction for every axis involved in
the transformation. The assignment of TU bits matches the channel axis view of the round
axes. The TU information is only evaluated for the up to 3 possible round axes which are
included in the transformation:
Bit0: Axis 1, TU bit = 0 : 0 degrees <= round axis angle < 360 degrees
Bit1: Axis 2, TU bit = 1 : –360 degrees < round axis angle < 0 degrees
The start position of a round axis is C = 0. By programming C = 270, the round axis travels to
the following target positions:
C = 270: TU bit 0, positive direction of rotation
C = –90: TU bit 1, negative direction of rotation
Further behavior
Mode change
The "Cartesian PTP travel" function is only useful in the AUTO and MDA modes of
operation. When changing the mode to JOG, the current setting is retained.
When the G code PTP is set, the axes will traverse in MCS. When the G code CP is set, the
axes will traverse in WCS.
Power On/RESET
After a power ON or after a RESET, the setting is dependent on the machine data
$MC_GCODE_REST_VALUES[48]. The default traversal mode setting is "CP".
REPOS
If the function "Cartesian PTP travel" was set during the interruption block, PTP can also be
used for repositioning.
Job planning
Programming Manual, 03/2006 Edition, 6FC5398-2BP10-1BA0
Transformations
7.9 Cartesian PTP travel
7-71