Siemens SIMATIC FM 351 - Incremental Encoders

9
9-18
FM 351 Positioning Function Module
EWA 4NEB 720 6001-02
Take note of the following requirements for a loop traverse:
 If you have parameterized a loop traverse against the traverse direction to
the target, the target position which can be approached at a maximum is
located at:
– With positive traverse direction
Target < SLE -
1
/
2
Target range - Negative switch-off difference -
Positive switchover difference
– With negative traverse direction
Target > SLS +
1
/
2
Target range + Positive switch-off difference +
Positive switchover difference
 A loop traverse is not executed if the target is approached in the direction
of the loop traverse.
 If you have parameterized a loop traverse in the traverse direction to the
target, the target position which can be approached at a maximum is lo-
cated at:
– With positive traverse direction
Target < SLE -
1
/
2
Target range
– With negative traverse direction
Target > SLS +
1
/
2
Target range
The figure below shows you the position of the fictitious target based on
positioning with loop traverse to the maximum target position in the positive
direction.
Fictitious target
Switchover difference, negative Switch-off difference, positive
1
2
3
v
rapid
v
creep
½ target range
1
2
Target
-v
creep
3
Change of
direction
Figure 9-4 Loop Traverse to a Target at the Software Limit Switch End
Requirements
Example
Operating Modes and Settings