Siemens SINUMERIK 840D sl Function Manual page 880

Rotary Axes (R2)
Modulo 360 degrees
Starting position for the modulo rotary axis
A start position, not equal to zero, can be specified in machine data for the modulo range:
MD30340 $MA_MODULO_RANGE_START.
This allows, for instance, a modulo range of -180° to +180° with a presetting of -180 in
MD30340.
The default setting of 0 (degrees) defines a modulo range of 0° - 360°.
Figure 13-4
Application
By adjusting the following two machine data
MD30503 $MA_INDEX_AX_OFFSET
MD30340 $MA_MODULO_RANGE_START,
indexing positions of modulo indexing axes can be implemented in the same way as for the
modulo range.
References:
/FB2/ Function Manual Extended Functions; Indexing Axes (T1)
880
Starting position of -180° changes the modulo range to -180° to + 180°
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Extended Functions