Siemens SINUMERIK 840Di sl Programming Manual page 148

Motion commands
4.11 Circular interpolation with tangential transition (CT)
Determining the direction of the tangent
The direction of tangent at the start point of a CT block is determined from the end tangent of
the programmed contour of the previous block with a traversing movement.
Any number of blocks without traversing information may lie between this block and the
current block.
Programming
CT X... Y... Z...
Parameters
CT
X Y Z
Note
CT is modal.
As a rule, the circle is uniquely defined by the direction of the tangent, as well as the start
and end points.
148
Circle with tangential transition
End point in Cartesian coordinates
Programming Manual, 11/2006, 6FC5398-1BP10-2BA0
Fundamentals