Siemens sinumerik 840D sl Function Manual page 144

Detailed description
2.2 Referencing and synchronization of gantry axes
2.2 Referencing and synchronization of gantry axes
2.2.1 Introduction
Misalignment after starting
Immediately after the machine is switched on, the leading and synchronized axes may not
be ideally positioned in relation to one another (e.g. misalignment of a gantry). Generally
speaking, this misalignment is relatively small so that the gantry axes can still be referenced.
In special cases (e.g. gantry axes were stopped owing to a disturbance, power failure or
EMERGENCY STOP), the dimensional offset must be checked for permissible tolerance
values and a compensatory motion executed if necessary before the axes are traversed.
To execute this compensatory motion, the gantry grouping must be invalidated by means of
the following machine data:
MD37140 $MA_GANTRY_BREAK_UP (invalidate gantry grouping)
Gantry synchronization
All gantry axes must first be referenced and then synchronized after the control system is
switched on. During gantry synchronization, all gantry axes approach the reference position
of the gantry grouping in the decoupled state. The reference position of the gantry grouping
for referencing the gantry axes corresponds to the reference position of the leading axis:
MD34100 $MA_REFP_SET_POS (reference point value/destination point for distancecoded
system)
Otherwise, the reference position is the current actual position of the leading axis.
These operations for referencing and synchronizing the gantry axes are executed
automatically in accordance with a special flowchart.
Referencing process
The flowchart for referencing gantry axes using an incremental measuring system is as
follows:
Section 1:
Referencing of the leading axis
The axis-specific referencing of the gantry axis will be started by the active machine function
REF upon the leading axis' interface signal from the PLC user program:
DB31, ... DBX4.7/4.6 (traversing key plus/minus)
The leading axis approaches the reference point (operational sequence as for reference
point approach).
References:
/FB1/ Function Manual, Basic Functions, Reference Point Approach (R1)
12
Special functions: Gantry Axes (G1)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0