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Positioning
10.7.2 Zero Offset
By transferring a zero offset (NVER), you can allocate a new actual value to the current position.
You may also make a distinction as to whether or not actual-value matching should take the last
(old) zero offset that was transferred into account.
The specified zero offset is taken into account when the actual value is computed and during syn-
chronization of the actual value.
a) Relative zero offset
The new actual value is computed as followed when you specify a relative zero offset:
Actual
The actual value thus changes by the difference between the old and the new zero offset,
thus ensuring that the zero offset last transferred always mirrors the distance value between
the zero point of the actual value range and the reference point. If a zero offset of 0 is spe-
cified, the position at which the actual value=0 is the reference point.
Limit switch
Traverse
-10 000
range
NVER=0
1)
Traverse
- 10 000
range
NVER=1000
2)
Traverse
- 9 000
range
NVER=500
3)
Traverse
- 9 500
range
NVER=0
4)
Traverse
- 10 000
range
Explanation:
The values NVER=0, NVER=1000, NVER=500 and NVER=0 were transferred
in succession as relative zero offset.
Note
When defining a zero offset, care must be taken that the entire traversing range is
covered by the actual value and that the actual value does not enter the overrange.
10-26
=Actual
+ Zero offset
new
old
Reference point
Fig. 10-19. Relative Zero Offset
- Zero offset
rel.,new
Current
position
0
3 000
1 000
4 000
500
3 500
0
3 000
rel.,old
Limit switch
+10 000
+10 000
+11 000
+10 500
+10 000
EWA 4NEB 811 6120-02a
IP 240
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