Siemens SINUMERIK 840D sl Programming Manual page 150

Measuring Cycles for Milling and Machining Centers
5.4 CYCLE977 workpiece: Measure hole/shaft/groove/web/rectangle parallel to axes
The safety zone (diameter or width) for shaft, hole, web, and groove is defined in _SZA.
For a rectangle, the safety zone (length) is defined with _SZA in the abscissa and with _SZO
in the ordinate.
Position after end of measuring cycle
When measurement is complete the probe is positioned above the calculated center point or
center at starting position height.
NOTICE
Precise measurement is only possible with a probe calibrated under the measurement
conditions, i.e. working plane, orientation of the spindle in the plane and measuring velocity
are the same for both measurement and calibration. Deviations can cause additional
measuring errors.
The range of positions of the center or diameter, or groove, web width, rectangle length,
must be within the value specified in _FA for all workpieces to be measured.
Otherwise, there is danger of collision or the measurement cannot be performed!
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Programming Manual, 03/2009 Edition, 6FC5398-4BP10-2BA0
Measuring cycles