HEIDENHAIN TNC 640, User Manual, Page: 484 / 948

Miscellaneous Functions | Miscellaneous functions for coordinate entries
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HEIDENHAIN | TNC 640 | Conversational Programming User's Manual | 10/2017
Behavior with M92 – Additional machine reference point
Refer to your machine manual.
In addition to the machine datum, the machine tool
builder can also define an additional machine-based
position as a machine reference point.
For each axis, the machine tool builder defines the
distance between the machine reference point and the
machine datum.
If you want the coordinates in positioning blocks to be based on the
additional machine reference point, end these block with M92.
Radius compensation remains the same in blocks that
are programmed with
M91
or
M92
. The tool length will
not be taken into account.
Effect
M91 and M92 are effective only in the blocks in which M91 and
M92 have been programmed.
M91 and M92 take effect at the start of block.
Workpiece preset
If you want the coordinates to always be referenced to the machine
datum, you can disable the setting of presets for one or more axes.
If presetting is inhibited for all axes, the control no longer displays
the
SET PRESET
soft key in the
Manual operation
mode.
The figure shows coordinate systems with the machine and
workpiece datum.
M91/M92 in the Test Run mode
In order to be able to graphically simulate M91/M92 movements,
you need to activate working space monitoring and display the
workpiece blank referenced to the defined preset.
Further information: "Showing the workpiece blank in the working
space ", page 815