Siemens SINUMERIK 840D sl Programming Manual page 329

The position of the surfaces is defined in workpiece coordinates in _SETVAL.
The workpiece probe calibrated is selected with _PRNUM. The associated array _WP[ ] in
data block GUD6.DEF is _WP[_PRNUM-1,...].
Prerequisite
The surface must be parallel to an axis of the workpiece coordinate system and have low
surface roughness.
The workpiece probe is called as a tool with tool offset and positioned opposite the
calibration surface. 5xy should be entered as the tool type.
Parameter
Parameter
_MVAR
_SETVAL
_MA
_MD
_PRNUM
1) It is also possible to calibrate in the 3rd axis (Y in G18), provided that this axis exists.
Additional parameters _VMS, _TZL, _TSA, _FA and _NMSP also apply.
NOTICE
The first time calibration is performed the default setting in the array of the probe is still "0".
For that reason _TSA> probe ball radius must be programmed to avoid alarm "Safe area
violated".
Measuring cycles
Programming Manual, 03/2009 Edition, 6FC5398-4BP10-2BA0
Data type
0
REAL
1, 2, 3
1)
0 positive axis direction
1 negative axis direction
INT
Measuring Cycles for Turning Machines
6.4 CYCLE973 Calibrating workpiece probes
Meaning
Calibration on surface (workpiece-related)
Setpoint referred to the workpiece zero, for facing
axis in the diameter (DIAMON)
Measuring axis
Measuring direction
Probe number
329