Siemens sinumerik 802d sl Operation And Programming Manual page 138

Programming
8.2 Positional data
Programming
G90
G91
X=AC(...)
X=IC(...)
Fig. 8-4
Absolute dimensioning G90
With absolute dimensioning, the dimensioning data refers to the zero of the coordinate
system currently active (workpiece or current workpiece coordinate system or machine
coordinate system). This is dependent on which offsets are currently active: programmable,
settable, or no offsets.
Upon program start, G90 is active for all axes and remains active until it is deselected in a
subsequent block by G91 (incremental dimensioning data) (modally active).
Incremental dimensioning G91
With incremental dimensioning, the numerical value of the path information corresponds to
the axis path to be traversed. The leading sign indicates the traversing direction.
G91 applies to all axes and can be deselected in a subsequent block by G90 (absolute di-
mensioning).
Specification with =AC(...), =IC(...)
After the end point coordinate, write an equality sign. The value must be put in round brack-
ets.
Absolute dimensioning is also possible for center points using =AC(...). Otherwise, the refe-
rence point for the circle center is the circle starting point.
Programming example
N10 G90 X20 Y90
N20 X75 Y=IC(–32)
...
N180 G91 X40 Y20
N190 X–12 Y=AC(17)
8-138
; Absolute dimensioning
; Incremental dimensioning
; Absolute dimensioning for a certain axis (here: X axis), non-modal
; Incremental dimensioning for a certain axis (here: X axis), non-modal
Absolute dimensions
Y
P2
P3
P1
Different dimensioning types in the drawing
SINUMERIK 802D sl Operation and Programming Nibbling (BP-N), 06/2006 Edition
Y
X
; Absolute dimensioning
; X dimensioning still absolute, Y incremental dimensioning
; Switching to incremental dimensioning
; X still incremental dimensioning, Y absolute
Incremental dimension
P2
P3
P1
X
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