Siemens SINUMERIK 840Di sl Programming Manual page 210

Path Action
5.3 Continuous-path mode (G64, G641, G642, G643, G644)
G641 also operates with "Look Ahead" predictive velocity control. Corner rounding blocks
with a high degree of curvature are approached at reduced velocity.
Continuous-path mode G64/G641 over several blocks
The following points should be noted in order to prevent an undesired stop in the path motion
(relief cutting):
• Auxiliary function outputs trigger a stop (exception: high-speed auxiliary functions and
• Intermediate blocks, which contain only comments, calculation blocks or subroutine calls
Extensions of corner rounding
If FGROUP does not contain all the path axes, there is often a step change in the velocity at
block boundaries for those axes excluded from FGROUP; the control limits this change in
velocity to the permissible values set in MD32300 $MA_MAX_AX_ACCEL and MD32310
$MA_MAX_ACCEL_OVL_FACTOR. This braking operation can be avoided through the
application of a rounding function, which "smoothes" the specific positional interrelationship
between the path axes.
Corner rounding with G641
You can activate a modal corner rounding action by programming G641 and specifying a
rounding radius with ADIS (or ADISPOS in rapid traverse). Within this radius about the block
change point, the control is free to ignore the path construct and replace it with a dynamically
optimized path. Disadvantage:Only one ADIS value is available for all axes.
210
auxiliary functions during movements).
do not affect the movement.
Programming Manual, 11/2006, 6FC5398-1BP10-2BA0
Fundamentals