HEIDENHAIN ITNC 530 - CONVERSATIONAL PROGRAMMING User Manual page 224

Central angle CCA and arc radius R
The starting and end points on the contour can be connected with four
arcs of the same radius:
Smaller arc: CCA<180°
Enter the radius with a positive sign R>0
Larger arc: CCA>180°
Enter the radius with a negative sign R<0
The direction of rotation determines whether the arc is curving
outward (convex) or curving inward (concave):
Convex: Direction of rotation DR– (with radius compensation RL)
Concave: Direction of rotation DR+ (with radius compensation RL)
Example NC blocks
10 L X+40 Y+40 RL F200 M3
11 CR X+70 Y+40 R+20 DR– (ARC 1)
or
11 CR X+70 Y+40 R+20 DR+ (ARC 2)
or
11 CR X+70 Y+40 R-20 DR– (ARC 3)
or
11 CR X+70 Y+40 R-20 DR+ (ARC 4)
The distance from the starting and end points of the arc
diameter cannot be greater than the diameter of the arc.
The maximum radius that can be entered directly is
99.9999 m, with Q parameter programming 210 m.
You can also enter rotary axes A, B and C.
224 Programming: Programming Contours