Siemens SIMATIC FM 353 Manual page 292

Writing Traversing Programs
Axis as rotary axis
If the axis is operated as a rotary axis, the measuring system must be adjusted in
such a way that the measurement scale refers to the full circle (e.g. 0_ and 360_).
S Reference-measure input G90
In a full circle with 360_, reference-measure programming (G90) has the pecu-
liarity that there are always two options for reaching the set position.
Set position
315_
270_
225_
Fig. 10-3
Option 1:
With G90, the axis autonomously always takes the shortest path to reach the
set position of 45_, going via 0_ to 315_.
Option 2:
The control signals (R+) or (R−) force the respective direction of the axis - in
this example 45_ via 180_ to 315_. (R+) or (R−) must already be pending when
positioning is activated (START).
Note
The direction (R+) or (R−) must be specified sufficiently in advance. A traversing
direction cannot be forced on a traversing block that is already active, or on the
traversing blocks (up to 4) that have already been calculated in advance in G64
operation.
Operation with option 1 or option 2 is at the user's discretion.
10-10
Option 1
Actual position
0_
45_
90_
135_
180_
/ N G1 G2 G3 X/t
10 90
315
Rotary axis
Option 2
Set position Actual position
0_
315_
270_
225_
180_
with direction R+ specified
F M1 M2 M3 D
100
FM 353 Stepper Drive Positioning Module
45_
90_
135_
6ES7 353-1AH01-8BG0