Siemens Sinumerik 840D sl Programming Manual page 119

PLC signal "Measurement input = 1"
With the rising edge of the measurement input 1, the current axis positions are stored in the
axial system parameters or $AA_MM[<Axis>], $AA_MW[<Axis>]. These parameters can be
read in the Siemens mode.
$AA_MW[X]
$AA_MW[Y]
$AA_MW[Z]
$AA_MM[X]
$AA_MM[Y]
$AA_MM[Z]
Note
Alarm 21700 is output if G31 is activated when the measuring signal is still active.
Program continuation after the measuring signal
If incremental axis positions are programmed in the next block, these axis positions are
related to the measuring point, i.e. the reference point of the incremental position is the axis
position at which the delete distance-to-go was executed by the measuring signal.
If the axis positions in the next block are programmed as absolute, then the programmed
positions are approached.
Note
No cutter radius compensation should be active in a block containing G31. Hence, the cutter
radius compensation is to be deselected before programming of G31, with G40.
ISO Milling
Programming Manual, 06/09, 6FC5398-7BP10-1BA0
Saving the coordinate value of the X axis in the workpiece coordinate system
Saving the coordinate value of the Y axis in the workpiece coordinate system
Saving the coordinate value of the Z axis in the workpiece coordinate system
Saving the coordinate value of the X axis in the machine coordinate system
Saving the coordinate value of the Y axis in the machine coordinate system
Saving the coordinate value of the Z axis in the machine coordinate system
Additional functions
4.6 Measuring functions
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