Siemens Sinumerik 802D sl Programming Manual page 30

Commands Calling Axis Movements
2.1 Interpolation commands
Center of arc
The center of arc can be specified in two methods -- designation of the distance
from the start point to the center of the arc and designation of the radius of the arc.
Fig. 2-8
S Specifying the distance from the start point to the center.
Independent of the designated dimensioning mode (G90 or G91), the center of
an arc must be specified in incremental values referenced from the start point.
S Specifying the radius
When defining an arc, it is possible to specify the radius by using address R in-
stead of specifying the center of the arc by addresses I or K. This is called "cir-
cular interpolation with R designation" mode.
For the circular arc with the central angle of 180 deg. or smaller, use an R value
of "R > 0".
For the circular arc with the central angle of 180 deg. or larger, use an R value
of "R < 0".
Example of programming
G02 X(U) ⋅⋅⋅ Z(W) ⋅⋅⋅ R  ⋅⋅⋅ F ⋅⋅⋅;
Fig. 2-9
2-30
End point
+X
Z W
Center
X
2
180_ or larger
R < 0
Circular interpolation with radius R designation
SINUMERIK 802D sl/840D sl840D/840Di sl/840Di/810D ISO Turning -- 04.07 Edition
Start point
U
2
I
K
+Z
R
End point
180_ or smaller
R > 0
Start point
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04.07