Siemens SINUMERIK 840D sl Operating Manual page 63

The axis is referenced as soon as the reference point is reached. The actual value display is
set to the reference point value.
From now on, path limits, such as software limit switches, are active.
End the function via the machine control panel by selecting operating mode "AUTO" or
"JOG".
Universal
Operating Manual, 01/2015, 6FC5398-6AP40-5BA2
3. Select the axis to be traversed.
4. Press the <-> or <+> key.
The selected axis moves to the reference point.
If you have pressed the wrong direction key, the action is not accepted
and the axes do not move.
A symbol is shown next to the axis if it has been referenced.
Setting up the machine
3.2 Approaching a reference point
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