Detailed Description 
  2.4 Tool: Tool radius compensation 2D (TRC) 
Tool Compensation (W1) 
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0 
2-57 
•  At least two blocks must always be taken into consideration: 
– The SAR block itself 
– The block, which defines the approach or retraction direction 
Further blocks can be programmed between these two blocks. 
Machine data: 
MD20202 $MC_SAR_MAXNUM_DUMMY_BLOCKS 
is used to limit the number of possible dummy blocks. 
•  If tool radius compensation is activated simultaneously in an approach block, the first 
linear block of the SAR contour is the block, in which activation takes place. 
The complete contour generated by the SAR function is treated by tool radius 
compensation as if it has been programmed explicitly (collision detection, calculation of 
intersection, approach behavior NORM/KONT). 
•  The direction of the infeed movement and the position of the circle plane or the helix axis 
are defined exclusively by the active plane (G17 - G19) - rotated with an active frame 
where appropriate. 
•  On approach, a preprocessor stop must not be inserted between the SAR block and the 
following block, which defines the direction of the tangent. 
Whether programmed explicitly or inserted automatically by the controller, a preprocessor 
stop results, in this case, in an alarm. 
Response with REPOS 
If an SAR cycle is interrupted and repositioned, it resumes at the point of interruption on RMI. 
With RME, the contact point is the end point of the last SAR block; with RMB, it is the start 
point of the first SAR block. 
If RMI is programmed together with DISPR (reapproach at distance DISPR in front of 
interruption point), the reapproach point can appear in a subblock of the SAR cycle before 
the interruption subblock. 
Example 1 
The following conditions must be true: 
•  Smooth approach is activated in block N20 
•  X=40 (end point); Y=0; Z=0 
•  Approach movement performed with quadrant (G247) 
•  Approach direction not programmed, G140 is valid, i.e., because TRC is active (G42) and 
compensation value is positive (10), the contour is approached from the right 
•  Approach circle generated internally (SAR contour) has radius 20, so that the radius of 
the tool center path is equal to the programmed value DISR=10 
•  Because of G341, the approach movement takes place with a circle in the plane, resulting 
in a start point at (20, -20, 0) 
•  Because DISCL=5, point P2 is at position (20, -20, 5) and, because of Z30, point P1 is in 
N10 at (20, -20, 30)