Reference Run; Definition - HEIDENHAIN iTNC 530 Service Manual

19 Reference Run

19.1 Definition

The position value (the coordinates) of an axis position is defined with respect to a freely
selectable datum. When the axes are moved, the ACTUAL position is calculated incrementally.
When the machine is switched off, the reference between the axis position and the position
value is lost.
HEIDENHAIN linear encoders (except EnDat) are designed with one or more reference marks.
Reference marks
The reference marks identify an axis position at a known distance from the machine datum. The
position of the datum selected by the machine operator is defined with respect to the machine
datum.
The datum and the actual position can be reproduced as soon as the reference marks are
traversed.
The machine datum is the central reference mark of your machine tool.
Machine
It is defined by the machine tool builder.
datum
The machine datum is required for ...
For position encoders with distance-coded reference marks, the machine datum is defined with
Distance between
respect to the scale reference point, which is at the first reference mark after the beginning of
the scale reference
the measuring length.
point and the
If EnDat encoders are used, the machine datum refers to the datum of the EnDat encoder.
machinedatum
A corresponding angle encoder or also the motor encoder in the spindle motor may be used for
Spindle preset
spindle orientation.
July 2010
Workpiece
datum
Machine table
Measuring system
Defining the limits of traverse (software limit switches)
Moving to machine-referenced positions (such as tool change positions)
Setting the workpiece datum
MP 960.x contains the distance between scale reference point and machine datum.
Note
After removing and remounting a measuring system MP 960.x may have to be altered.
See "Resetting the machine datum" on page 18 – 288.
MP 3430.x contains the deviation of the reference mark from the desired position.
+Z
REF Value REF Value
–44.985 0
10 20 30 40
0
Workpiece
Reference mark
Machine datum
+X
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