Siemens SINUMERIK 840D sl Programming Manual page 845

specifications) either via the setting data $SC_CONTPREC or via the programmed contour
tolerance CTOL. The smaller the value and the smaller the K
greater the path feedrate is reduced on curved contours.
The "Programmable contour accuracy" function is activated or deactivated via the operations
CPRECON and CPRECOF in the NC program.
Syntax
CPRECON
...
CPRECOF
Meaning
CPRECON:
CPRECOF:
Together CPRECON and CPRECOF form the G function group 39 (programmable contour
accuracy).
Note
The user can specify a minimum velocity for the path feedrate via the setting data
$SC_MINFEED (minimum path feedrate with CPRECON).
The feedrate is not limited below this value, unless a lower F value has been programmed or
the dynamic limits of the axes require a lower path velocity.
Note
The "Programmable contour accuracy" function only considers the geometry axes of the path.
It has no effect on the velocities of positioning axes.
Example
Program code
N10 G0 X0 Y0
N20 CPRECON
N30 G1 G64 X100 F10000
N40 G3 Y20 J10
N50 G1 X0
...
NC programming
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
G command call: Switch "Programmable contour accuracy" on
Effectiveness: Modal
G command call: Switch "Programmable contour accuracy" off
Effectiveness: Modal
Comment
; Activate the "programmable contour accuracy".
; Machining with 10 m/min in the continuous-path
mode.
; Automatic feed limitation in circular block.
; Feedrate again without limitation (10 m/min).
Work preparation
3.14 Path traversing behavior
factor of the geometry axes, the
V
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