Siemens SINUMERIK 840D sl Function Manual page 562

M1: Kinematic transformation
7.6 Cartesian PTP travel
Reset
MD20152 $MC_GCODE_RESET_MODE[48] (group 49) defines which setting is active after
RESET/end of parts program.
● MD=0: Settings are effected in accordance with machine data
● MD=1: Active setting remains valid
Selection
The setting MD20152 $MC_GCODE_RESET_MODE[48] =0, with MD20150
$MC_GCODE_RESET_VALUES[48] can activate the following:
● MD=2:
● MD=3:
Secondary conditions
The following should be noted with respect to tool movement and collision:
● As the PTP command can produce significantly different tool movements to the CP
● Machine axes always traverse the shortest possible path in response to TRANSMIT and
The following combinations with other NC functions are not legal:
● No tool radius compensation (TRC) may be active with PTP.
● With PTPG0, for active tool radius compensation (TRC), traverse is by CP.
● PTP does not permit smooth approach and retraction (SAR).
● With PTPG0, CP travel is used for smooth approach and retraction (SAR).
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MD20150 $MC_GCODE_RESET_VALUES[48]
Cartesian PTP travel as previously or
PTPG0, traverse only G0 blocks with PTP automatically and then switch over to CP again
command, any pre-existing subroutines which have been written independently of the
active transformation must be adapted to take account of the risks of collision when
TRANSMIT is active. This applies particularly in the case of command PTPG0.
PTP. Minor displacements in the block end point can cause the rotary axis to rotate by -
179.99° instead of + 179.99°, even though the block end point has hardly changed.
G0 and G41 do not exclude each other in principle. However, an active PTP generates
different contours to those computed for the TRC, resulting in the activation of a TRC
alarm.
Since G0 and G41 do not exclude each other, switch-over to CP is done automatically
when tool radius compensation is active. The radius compensation therefore works on
the basis of clearly defined contours.
SAR requires a contour in order to construct approach and retraction motion. This
information is not available with PTP.
SAR requires a contour in order to construct approach and retraction motion and to be
able to lower and raise tangentially. The blocks required for this purpose are therefore
traversed with the CP command. The G0 blocks up to the actual approach contour are
executed with PTP and therefore quickly. The same applies to the retract blocks.
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
Extended Functions