Siemens sinumerik 840D sl Function Manual page 104

Detailed description
2.11 Online tool length offset
Note
For further information about programming plus programming examples, please see:
References: /PGA/Chapter "Transformations"
As long as online tool length offset is active, the VDI signal on the NCK → PLC interface in
the following interface signal is set to 1:
DB21, ... DBX318.2 (TOFF active)
While a correction movement is active, the VDI → signal in the following interface signal is
set to 1:
DB21, ... DBX318.3 (TOFF movement active)
Reset
Compensation values can be reset with the TOFFOF( ) command. This instruction triggers a
preprocessing stop.
Accumulated tool length compensations are cleared and incorporated in the basic coordinate
system. The run-in is synchronized with the current position in main run. Since no axes can
be traversed here, the values of $AA_IM[ ] do not change. Only the values of the variables
$AA_IW[ ] and $AA_IB[ ] are changed. These variables now contain the deselected share of
tool length compensation.
Once "Online tool length offset" has been deselected for a tool direction, the value of system
variable $AA_TOFF[ ] or $AA_TOFF_VAL[ ] is zero for this tool direction. The following
interface signal is set to 0:
DB21, ... DBX318.2 (TOFF active)
Alarm 21670
An existing tool length offset must be deleted via TOFFOF( ) so that alarm 21670 "Channel
%1 block %2, illegal change of tool direction active due to $AA_TOFF active" is suppressed:
• When the transformation is deactivated with TRAFOOF
• On switch-over from CP to PTP travel.
• If a tool length offset exists in the direction of the geometry axis during geometry
• If a tool length offset is present during change of plane.
• When changing from axis-specific manual travel in JOG mode to PTP as long as a tool
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replacement.
length compensation is active. There is no switchover to PTP.
Special functions: 3-Axis to 5-Axis Transformation (F2)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0