Siemens sinumerik 840D sl Function Manual page 149

Loss of synchronization
The synchronization of the gantry grouping is lost (IS "Gantry grouping is synchronized" → 0)
if:
• The gantry axes were in "Follow-up" mode
• The reference position of a gantry axis is lost, e.g. during "Parking" (no measuring system
• One gantry axis is re-referenced (IS "Referenced/Synchronized" changes to 0)
• The gantry grouping was invalidated:
In cases where the gantry grouping has lost synchronization during operation as the result of
a disturbance, then the gantry synchronization process can be restarted directly by means of
IS "Start gantry synchronization" (condition: IS "Referenced/Synchronized" = 1 for all axes in
the gantry grouping). In this case, the synchronizing axes traverse the current actual position
of the leading axis in the decoupled state.
If an emergency stop occurs while a gantry grouping is moving, and then rescinds, and both
axes have drifted apart less than the zero speed tolerance of the slave axes, then the gantry
grouping will automatically synchronize. It does not have to go in the BA REFP anymore.
Automatic synchronization can be stopped with the interface signal DBxx.DBX29.5 from the
master axis.
Reference point selection
To ensure that the shortest possible paths are traversed when the gantry axes are
referenced, the reference point values from leading and synchronized axes should be the
same in the machine data:
MD34100 $MA_REFP_SET_POS (reference point value/destination point for distancecoded
system)
Allowance for deviations in distance between the zero mark and the reference point must be
made for specific axes via the machine data:
MD34080 $MA_REFP_MOVE_DIST (reference point distance)
MD34090 $MA_REFP_MOVE_DIST_CORR (reference point offset/absolute offset)
Special functions: Gantry Axes (G1)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0
active)
MD37140 $MA_GANTRY_BREAK_UP (invalidate gantry grouping)
2.2 Referencing and synchronization of gantry axes
Detailed description
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