Machine Data For Equidistant Indexing Intervals; Features - Siemens SINUMERIK 840D Function Manual

Note
With the system variables $AA_ACT_INDEX_AX_POS_NO it is not possible to determine
whether an indexing position has been reached. To this end, one of the two following NC/PLC
interface signals must also be evaluated:
DB31, ... DBX76.6 (indexing position reached)
DB31, ... DBX60.7 (exact stop fine reached)
Example
Assumptions:
● MD10940 $MN_INDEX_AX_MODE, bit 0 == 1
● The axis is located in front of an indexing position outside the tolerance window "exact stop
fine" (DB31, ... .DBX60.7 == 0)
Although system variable $AA_ACT_INDEX_AX_POS_NO indicates indexing position 2, with
the "Traverse to next position" command, indexing position 3 is not approached, but first
precisely to indexing position 2. Only when the axis is precisely at (DB31, ... .DBX60.7 == 1) -
or is located after the displayed indexing position, using the "Traverse to next position"
command, the next indexing position is approached, in the example, indexing position 3. This
means that the indexing position is approached that is the closest in the traversing direction !
Under certain circumstances, it is therefore necessary to issue the "traverse to next position"
command twice to move from the currently displayed indexing position to the next indexing
position.
8.3.2

Machine data for equidistant indexing intervals

8.3.2.1

Features

Distance between indexes
The index distance is determined for equidistant index intervals according to the following
formula:
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA
T1: Indexing axes
8.3 Commissioning
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