Siemens SINUMERIK 840DE Programming Manual page 139

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.
Fundamentals
Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
4.11 Circular interpolation with tangential transition (CT)
Circle with tangential transition
End point in Cartesian coordinates
Programming Motion Commands
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