Siemens Sinumerik 840D Operating Turning page 58

Section 2
Notes
B503
B503
Absolute and incremental dimensioning, mixed programming
2.2 Incremental dimensioning
Code G91
(also known as chain dimensioning).
All position statements refer to the current starting position of the tool.
The programmed value states the coordinate distance, by which the tool is
to traverse during the ensuing machining step.
Code G91 is modally active for all axes simultaneously and can be reset to
absolute dimensioning with code G90.
Page 4
Coordinates:
An example for milling.
G91 X
20
P1
P2 30
P3 20
Coordinates:
An example for turning
(All dimensions for X are ra-
dius values DIAMOF).
G91 X
P1 12.5 -7.5
P2 7.5 -7.5
0
P3
10
P4
840D/828D SINUMERIK Operate
Y
35
20
-35
Z
-10
-10