HEIDENHAIN iTNC 530 User Manual page 461

If your machine is equipped with absolute encoders, you
can leave out crossing the reference marks. In such a
case, the TNC is ready for operation immediately after the
machine control voltage is switched on.
If your machine is equipped with incremental encoders,
you can activate traverse range monitoring even before
reference mark traverse by pressing the SW LIMIT
MONITORING soft key. Your machine tool builder can
provide this function axis-specifically. Remember that by
pressing the soft key, traverse range monitoring is not
necessarily active in all axes. The machine tool manual
provides further information.
The TNC is now ready for operation in the Manual Operation mode.
The reference points need only be crossed if the machine
axes are to be moved. If you intend only to write, edit or
test programs, you can select the Programming and
Editing or Test Run modes of operation immediately after
switching on the control voltage.
You can cross the reference points later by pressing the
PASS OVER REFERENCE MARK soft key in the Manual
Operation mode.
HEIDENHAIN iTNC 530 461