Referencing; Definition - HEIDENHAIN iTNC 530 Service Manual

18 Referencing

18.1 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.
If there is an interruption in power, the reference between the axis position and the position
value is lost.
Reference marks HEIDENHAIN linear encoders are designed with one or more reference marks. The reference
marks identify an axis position at a known distance from the machine datum. The position of the
freely selectable datum 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.
Machine The machine datum is determined by the machine manufacturer.
datum It is required for:
Distance between For distance-coded reference marks, the machine datum is defined with respect to the scale
the scale reference reference point, which is at the first reference mark after the beginning of the measuring length.
point and the

machine datum
Spindle preset A corresponding angle encoder or also the motor encoder in the spindle motor may be used for
spindle orientation.

May 2006
+Z
Workpiece
datum
0
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 "Re-Setting the Machine Datum" on page 17 – 284.
MP 3430.x contains the deviation of the reference mark from the desired position.
Note
After exchanging the angle encoder or the motor encoder in the spindle motor, it might be
necessary to set MP 3430 again.
See "Resetting the Spindle Orientation" on page 17 – 293.
REF Value REF Value
–44.985 0
10 20 30 40
+X
Workpiece
Reference mark
Machine datum
18 – 301