Siemens SIMATIC FM 353 Manual page 290

Writing Traversing Programs
Dimensions G90, G91
The traversing movement at a specific point can be described by
S Absolute measure input G90 or
S Relative measure input G91
You can switch back and forth at will between absolute and incremental input.
The status at startup is reference-measure programming, G90.
G90 and G91 are modal.
Absolute dimensioning G90
Absolute dimensioning is the method used to specify dimensions that generally
refer to the coordinate system.
Fig. 10-1
Note
To ensure precise reproduction of the program, the first block should contain refer-
ence-measure programming.
10-8
/ N G1 G2 G3 X/t
90
20
Programmed
position
0
10 20 30
Reference-measure input G90
F M1 M2 M3 D
100
Actual position
40 50 mm
FM 353 Stepper Drive Positioning Module
6ES7 353-1AH01-8BG0