Siemens SINUMERIK 840D sl Function Manual page 688

K2: Axis Types, Coordinate Systems, Frames
10.4 Coordinate systems
System variable
$AC_PRESET
The axis-specific system variable $AC_PRESET provides the vector from the zero point of the
currently offset MCS' to the zero point of the original MCS
axis.
$AC_PRESET<axis> = $AC_PRESET<axis> + "current actual position of the axis in the MCS"
- "PRESETON actual position"
The work offset can be undone with the system variables:
PRESETON(<axis>, $VA_IM + $AC_PRESET[<axis>]) ; "current actual
position of the axis in the MCS'" + "offsets"
Example
Program code
N10 G1 X10 F5000
N20 PRESETON(X, $AA_IM[X]+70) ; Actual value = 10 + 70 = 80 => $AC_PRESET
= $AC_PRESET - 70
Supplementary conditions
Axes for which PRESETON must not be used
● Traversing positioning axes
● Traversing command axes in spindle mode
● Traversing concurrent positioning axes (FC18)
● Axes involved in a transformation
● Traversing path axes
● Reciprocating axes
● Axes on which one or more of the following safety functions (Safety Integrated) are active
– Enable safe limit switch
– Enable safe cam, pair 1 ... 4, cam +/-
● Hirth axes
● Synchronized axes of a gantry grouping
● Axes for which the reference point approach from the part program (G74) is active
● Slave axis of a speed/torque coupling (master-slave)
688
MD36901 $MA_SAFE_FUNCTION_ENABLE[<safe axis>], bit 1 = 1
MD36901 $MA_SAFE_FUNCTION_ENABLE[<safe axis>], bits 8 ... 15 = 1
after the referencing of the machine
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Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions