Online Tool Length Offset - Siemens SINUMERIK 840D sl Function Manual

F2: Multi-axis transformations

1.12 Online tool length offset

1.12 Online tool length offset
Functionality
Effective tool length can be changed in real time so that the length changes are also
considered for changes in orientation of the tool. System variable $AA_TOFF[ ] applies tool
length compensations in 3-D according to the three tool directions.
None of the tool parameters are changed. The actual compensation is performed internally by
means of transformations using an orientable tool length compensation.
The geometry identifiers are used as index. The number of active compensation directions
must be the same as the number of active geometry axes. All offsets can be active at the
same time.
Application
The online tool length compensation function can be used for:
• Orientation transformations (TRAORI)
• Orientable tool carriers (TCARR)
Note
Online tool length offset is an option and must be enabled beforehand. This function is only
practical in conjunction with an active orientation transformation or an active orientable
toolholder.
References: /FB/Function Manual Basic Machine; Tool Offset; Orientable Tool Holders (W1)
Block preparation
In the case of block preparation in run-in, the tool length offset currently active in the main run
is considered. In order to utilize the maximum permissible axis velocities as far as possible, it
is necessary to halt the block preparation with a stop preprocessing command (STOPRE)
while a tool offset is being generated.
The tool offset is always known at the time of run-in when the tool length offsets are not
changed after program start or if more blocks have been processed after changing the tool
length offsets than the IPO buffer can accommodate between run-in and main run. This
ensures that correct axis velocities are applied quickly.
The dimension for the difference between the currently active compensation in the
interpolator and the compensation that was active at the time of block preparation can be
polled in the system variable $AA_TOFF_PREP_DIFF[ ].
Note
Changing the effective tool length using online tool length offset produces changes in the
compensatory movements of the axes involved in the transformation in the event of changes
in orientation. The resulting velocities can be higher or lower depending on machine
kinematics and the current axis position.
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Function Manual, 09/2011, 6FC5397-2BP40-2BA0
Special Functions