Siemens Sinumerik 840D sl Programming Manual page 31

Return to reference point
Note
The G28 function is implemented with the shell cycle cycle328.spf. A transformation must
not be programmed for an axis which is to approach the reference point with G28 which
must approach the reference mark. The transformation is deactivated in cycle328.spf with
command TRAFOOF.
Automatic reference point approach for rotary axes
Rotary axes can be used for automatic reference point approach exactly as linear axes. The
approach direction of the reference traverse is defined with the machine data 34010
MD_$MA_REFP_CAM_DIR_IS_MINUS.
Figure 2-9
Additions to the commands for automatic reference point approach:
Tool radius compensation and defined cycles
G28 should not be used in operation with tool radius compensation (G41, G42) or in a
defined cycle!
G28 is used to interrupt the tool radius compensation (G40) with eventual axis traverse
movement to the reference point. Hence, tool radius compensation is to be deactivated
before G28 is issued.
Tool offset in G28
In G28, the interpolation point is approached with the current tool offset. The tool offset is
deselected when the reference point is finally approached.
ISO Milling
Programming Manual, 06/09, 6FC5398-7BP10-1BA0
Return to reference point - rotary axes
WARNING
2.2 Reference point approach with G functions
Drive commands
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