Siemens SINUMERIK 840D sl Function Manual page 861

Modulo rotary axis with/without working-area limitation
The PLC can set interface signal
DB31, ... DBX12.4
for dynamic activation/deactivation of the working-area limitation/software limit switches
associated with a modulo rotary axis (similar to rotary axes).
The NC feeds back the current status of the traversing-range limitation via interface signal
DB31, ... DBX74.4.
The monitoring function is activated if interface signal
DB31, ... ; DBX 12.4
has been set by the PLC.
The M/H function which causes the PLC to set the interface signal must be followed by
STOPRE, to ensure through synchronization that only the blocks after switchover are
monitored.
Supplementary conditions:
It is only possible to activate/deactivate software-limit-switch monitoring via the PLC interface
for modulo axes.
Traversing-range monitoring for modulo axes can be implemented only if the axis is
referenced and one limiting pair is active.
This always applies in the case of software limit switches, since these are always
activated/deactivated in pairs. To monitor working-area limitations correctly, both limitations
must have been activated, either via G26/G25 or setting data
SD43400 $SA_ WORKAREA_PLUS_ENABLE
and
SD43410 $SA_WORKAREA_MINUS_ENABLE.
Example of a traversing-range-limitation switchover
A pallet with several clamped workpieces should be machined successively on a modulo
rotary axis. This pallet is then replaced by one with a built-on axis whose operating range
must be monitored to prevent damage to supply lines.
Configuration:
MD30300 $MA_IS_ROT_AX[AX4] = 1
MD30310 $MA_ROT_IS_MODULO[AX4] = 1
MD36110 $MA_POS_LIMIT_PLUS[AX4] = 340
MD36100 $MA_POS_LIMIT_MINUS[AX4] = 350
Extended Functions
Function Manual, 09/2009, 6FC5397-1BP20-0BA0
R2: Rotary axes
13.3 Programming rotary axes
861