Siemens SINUMERIK 840D sl Function Manual page 178

Detailed description
2.3 Continuous -path mode
Differences between G642 - G643
With regard to their rounding behavior, commands G642 ad G643 differ as follows:
G642
With G642, the rounding travel is determined
based on the shortest rounding travel of all axes.
This value is taken into account when generating
a rounding block.
With G642, the rounding area results from the
smallest tolerance setting.
Constraints
Expansion to include contour tolerance and orientation tolerance exists only in systems with
options for polynomial interpolation. The orientation-transformation option is also required for
rounding orientations with angular tolerance specification.
Restriction for protection zones with active radius compensation and tool orientation:
Although tool radius compensation is applied for a tool orientation, which is not perpendicular
to one of the three datum planes of the basic coordinate system, the protection zones are
not rotated onto the corresponding plane.
For G643 the following must apply in the machine data:
MD28530 $MC_MM_PATH_VELO_SEGMENTS > 0 (number of memory elements for
limiting the path velocity)
If this condition is met, the following machine data must apply to all the axes:
MD35240 $MC_ACCEL_TYPE_DRIVE = FALSE (acceleration characteristic line DRIVE for
axes on/off)
Expansion
Rounding with G642 and G643 has been extended so that the length of the rounding
distance can be specified directly instead of entering the maximum tolerances.
As with G641, the language commands ADIS = ... for G01 and ADISPOS = ... for G00 are
used respectively for this purpose.
Whether or not G642, G643 are specified with the maximum tolerances or the rounding
length, is set with the machine data:
MD20480 $MC_SMOOTHING_MODE (rounding behavior with G64x)
The following applies:
SMOOTHING_MODE = x4
SMOOTHING_MODE = 4x
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G643
In the case of G643, the rounding travel of each
axis can be different. The rounding travels are
taken into account axisspecifically and block-
internally.
Very different specifications for the contour
tolerance and the tolerance of the tool orientation
can only have effect with G643.
G643 with ADIS or ADISPOS
G642 with ADIS or ADISPOS
Basic logic functions: Continuouspath Mode, Exact Stop, LookAhead (B1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0