Siemens SINUMERIK 840D sl Function Manual page 977

Bit
0
The following graphics will illustrate the difference between Bit 0 = 0 and Bit 0 = 1:
Figure 16-1
Extended Functions
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Value Description
0 The indexing position changes when the indexing position is reached ("exact stop
fine" window) and remains unchanged until the next indexing position is reached. The
indexing area thus begins at one indexing position and ends in front of the next
indexing position.
1 The indexing position changes when half the indexing position is reached.
A quasi-symmetrical indexing area is thus applied around the indexing position
(symmetrical only on linear axes with equidistant indexing or modulo rotary axes on
which the indexing area is an integer multiple of the modulo range (MD30330
$MA_MODULO_RANGE), otherwise proportional to the distances between the
indexing positions).
On modulo rotary axes, the area between the last indexing position and the first
indexing position is divided proportionally based on the lengths of the first indexing
area and the last indexing area.
Indexing position displays: Linear axis
Indexing Axes (T1)
Programming of indexing axes
977