Siemens SINUMERIK 840DE Programming Manual page 330

Tool offsets
8.9 Contour approach and retraction (NORM, KONT, KONTC, KONTT)
3D representation: At the same time the curvature is adjusted to the circular path of the full
circle, the axes moves from Z60 to the plane of circle Z0.
Direct approach to perpendicular position, G41, G42, NORM
The tool travels in a straight line directly to the contour and is positioned perpendicular to the
path tangent at the starting point.
Selection of the approach point
When NORM is active, the tool travels directly to the compensated starting position
irrespective of the approach angle programmed for the travel movement (see diagram).
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Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
Fundamentals