HEIDENHAIN TNC 620 E, User Manual

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Miscellaneous Functions | Miscellaneous functions for coordinate entries
11
HEIDENHAIN | TNC 620 | Conversational Programming User's Manual | 10/2017
471
11.3 Miscellaneous functions for coordinate
entries
Programming machine-referenced coordinates: M91/
M92
Scale datum
On the scale, a reference mark indicates the position of the scale
datum.
Machine datum
The machine datum is required for the following tasks:
Define the axis traverse limits (software limit switches)
Approach machine-referenced positions (e.g. tool change
positions)
Set a workpiece preset
The distance in each axis from the scale datum to the machine
datum is defined by the machine manufacturer in a machine
parameter.
Standard behavior
The control references the coordinates to the workpiece datum.
Further information: "Presetting without a 3-D touch probe",
page 652
Behavior with M91 – Machine datum
If you want the coordinates in a positioning block to be referenced
to the machine datum, end the block with M91.
If you program incremental coordinates in an M91 block,
enter them with respect to the last programmed M91
position. If no M91 position is programmed in the active
NC block, then enter the coordinates with respect to the
current tool position.
The coordinate values on the control screen reference the machine
datum. Switch the display of coordinates in the status display to
REF.
Further information: "Status displays", page 94