Siemens sinumerik 840D sl Function Manual page 103

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[ ].
The following machine data and setting data are available for configuring online tool length
compensation:
Machine data / setting data
MD21190 $MC_TOFF_MODE
MD21194 $MC_TOFF_VELO (speed online tool
offset)
MD21194 $MC_TOFF_ACCEL (acceleration
online tool offset)
SD42970 $SC_TOFF_LIMIT (upper limit of
offset value $AA_TOFF)
With the acceleration margin, 20% is reserved for the overlaid movement of online tool
length offset, which can be changed via the following machine data:
MD20610 $MC_ADD_MOVE_ACCEL_RESERVE(acceleration margin for overlaid
movements)
Activation
The TOFFON instruction can be used to activate online tool length offset from the parts
program for at least one tool direction, if the option is available. During activation an offset
value can be specified for the relevant direction of compensation and this is immediately
traversed.
Example: TOFFON(Z, 25).
Repeated programming of the instruction TOFFON( ) with an offset causes the new offset to
be applied. The offset value is added to variables $AA_TOFF[ ] as an absolute value.
Special functions: 3-Axis to 5-Axis Transformation (F2)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0
2.11 Online tool length offset
Meaning for online tool length compensation
The contents of $AA_TOFF[ ] are traversed as an
absolute value or integrated
Speed of online tool length offset
Acceleration of online tool length offset
Upper limit of tool length offset value
Detailed description
97