Siemens SINUMERIK 840D sl Function Manual page 123

Application
The online tool length compensation function can be used for:
● Orientation transformations (TRAORI)
● Orientable tool carriers (TCARR)
Note
The online tool length offset is an option. This function is only practical in conjunction with
an active orientation transformation or an active orientable toolholder.
Reference:
Function Manual, Basic Functions; Tool Offset, Section: Orientable toolholders (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.
MD21190 $MC_TOFF_MODE (operation of tool offset)
The following machine data can be used to set whether the content of the synchronization
variable $AA_TOFF[ ] is to be approached as an absolute value or whether an integrating
behavior is to take place:
MD21190 $MC_TOFF_MODE
The integrating behavior of $AA_TOFF[ ] allows 3D remote control. The integrated value is
available via the system variable $AA_TOFF_VAL[ ].
Special functions
Function Manual, 01/2015, 6FC5397-2BP40-5BA2
F2: Multi-axis transformations
2.12 Online tool length offset
123