Specifications

Positioning IP 240
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
new
=Actual
old
+ Zero offset
rel.,new
- Zero offset
rel.,old
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.
Fig. 10-19. Relative Zero Offset
Traverse
range
Current
position
Reference point
Traverse
range
0 3 000
1 000 4 000
500 3 500- 9 500
- 9 000
- 10 000
+10 500
+11 000
+10 000
0 3 000- 10 000 +10 000
Limit switch
Limit switch
-10 000 +10 000
NVER=0
1)
Traverse
range
Traverse
range
Traverse
range
NVER=500
3)
NVER=0
4)
NVER=1000
2)
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 EWA 4NEB 811 6120-02a