Siemens SINUMERIK 840D sl Function Manual page 101

<value>:
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"
- "PRESETONS actual position"
The work offset can be undone with the system variables:
PRESETONS(<axis>, $VA_IM + $AC_PRESET[<axis>]) ; "current actual
position of the axis in the MCS'" + "offsets"
Example
Work offset of the X axis MCS by 70 units.
The programmed end position of the X axis (command axis) is transformed to the new MCS
with PRESETONS.
Program code
N10 G1 X=10 F5000
; Traverse the X axis as command axis to position 200
N20 WHEN TRUE DO G71 POS[X]=200
; IF set position of the X axis in the MCS ($AA_IM[X]) >= 80
; THEN "actual position of the X axis in the MCS" = "set position of the X
axis in the MCS" + "offset"
;
;
axis" + "offset"
;
;
N30 WHEN G71 $AA_IM[X] >= 80 DO PRESETONS(X, $AA_IM[X]+70)
N40 G4 F3
Supplementary conditions
Axes for which PRESETONS must not be used
● Traversing command axes in spindle mode
● Traversing concurrent positioning axes (FC18)
● Axes involved in a transformation
Synchronized actions
Function Manual, 08/2018, 6FC5397-5BP40-6BA2
New current actual value of the machine axis in the machine coordinate
system (MCS)
The input is made in the active system of units (inch/metric)
An active diameter programming (DIAMON) is taken into account
Type:
"progr. end position of the X axis" = "progr. end position of the X
$AC_PRESET = $AC_PRESET - 70
3.7 Actions in synchronized actions
REAL
after the referencing of the machine
0
= 80 + 70 = 150
= 200 + 70 = 270
Detailed description
101