Siemens SIMATIC S7-300 Manual page 269

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 ).
Fig. 10-3 Rotary axis
Note
The direction (R+) or (R–) must be specified sufficiently in advance. A tra-
versing direction cannot be forced on a traversing block that is already ac-
tive, 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.
FM 354 Servo Drive Positioning Module
Reference-measure input G90
In a full circle with 360 , reference-measure programming (G90) has the
peculiarity that there are always two options for reaching the set position.
Option 1
Set position Actual position
0
315
270
225
180
/ N G1 G2 G3
10 90
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).
Incremental input G91
With incremental programming G91, the direction of rotation of the
rotary axis is defined by the sign of the position setpoint. Multiple rota-
tions can be programmed by setting a value > 360 as the position set-
point.
Writing Traversing Programs
Option 2
Set position
0
45
315
270
90
135
225
180
with direction R+ specified
X/t F M1 M2 M3 D
315 100
Actual position
45
90
135
10-9