Siemens SINUMERIK 840D sl Programming Manual page 226

Motion commands
9.6 Circular interpolation
Note
CT is modal.
As a rule, the circle is clearly defined by the tangent direction as well as the starting point and
end point.
Examples
Example 1: Milling
Program code
N10 G0 X0 Y0 Z0 G90 T1 D1
N20 G41 X30 Y30 G1 F1000
N30 CT X50 Y15
N40 X60 Y-5
N50 G1 X70
N60 G0 G40 X80 Y0 Z20
N70 M30
226
Milling a circular arc with CT directly after the
straight part.
Comment
; Activation of TRC.
; Circular-path programming with tangential
transition.
Programming Manual, 09/2011, 6FC5398-1BP40-2BA0
Fundamentals