Siemens SINUMERIK 840D sl Programming Manual page 516

Tool offsets
7.10 Online tool length compensation (TOFFON, TOFFOF)
Description
Block preparation
During block preparation in preprocessing, the current tool length offset active in the main
run is also taken into consideration. To allow extensive use to be made of the maximum
permissible axis velocity, it is necessary to stop block preparation with a STOPRE
preprocessing stop while a tool offset is set up.
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.
Variable $AA_TOFF_PREP_DIFF
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 variable $AA_TOFF_PREP_DIFF[ ].
Adjusting machine data and setting data
The following machine data is available for online tool length offset:
● MD 20610: ADD_MOVE_ACCEL_RESERVE acceleration margin for overlaid motion
● MD 21190: TOFF_MODE: content of system variable $AA_TOFF[ ] is recovered or
● MD 21194: TOFF_VELO velocity of online tool length offset.
● MD 21196: TOFF_ACCEL acceleration of online tool length offset.
● Setting data for presetting limit values
References: /FB3/ Function Manual, Special Functions; 3- to 5-Axis Transformations (F2).
516
integrated as an absolute value
SD 42970: TOFF_LIMIT upper limit of tool length offset value.
Programming Manual, 06/2009, 6FC5398-2BP20-0BA0
Job Planning