Siemens SINUMERIK 840D sl Programming Manual page 531

Limit angle using the working area limitation
For path movements, which oscillate back and forth, the tangent jumps through 180° at the
turning point on the path and the orientation of the following axis changes accordingly.
This behavior is generally inappropriate: The return movement should be traversed at the
same negative offset angle as the approach movement.
To do this, limit the working area of the following axis (G25, G26). The working area limit
must be active at the instant of path reversal (WALIMON).
If the offset angle lies outside the working area limit, an attempt is made to return to the
permissible working area with the negative offset angle.
Insert intermediate block at contour corners, TLIFT
At one corner of the contour the tangent changes and thus the setpoint position of the
following axis. The axis normally tries to compensate this step change at its maximum
possible velocity. However, this causes a deviation from the desired tangential position over
a certain distance on the contour after the corner. If such a deviation is unacceptable for
technological reasons, the instruction TLIFT can be used to force the control to stop at the
corner and to turn the following axis to the new tangent direction in an automatically
generated intermediate block.
Job Planning
Programming Manual, 06/2009, 6FC5398-2BP20-0BA0
8.1 Tangential control (TANG, TANGON, TANGOF, TLIFT, TANGDEL)
Path traversing behavior
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