# Fanuc Series 15i/150i-MA (Programming) Operators Manual

B-63324EN/03 PROGRAMMING 14.COMPENSATION FUNCTION
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- Rotation axis offset
Set offsets relative to the rotation angles of the rotation axes in
parameter No. 7517. The compensation vector calculation formula is
the same as that used for rotation axis origin compensation, except that
Bp and Cp are changed to rotation axis offsets.
When rotation axis origin compensation and rotation offsetting are set
at the same time, both compensations are performed.
When the tool axis is on the Z-axis, and the rotation axes are the B-axis
and C-axis, compensation vector calculation is performed as follows :
Xp = Lc * sin(B-(Bz+Bo)) * cos(C-(Cz+Co))
Yp = Lc * sin(B-(Bz+Bo)) * sin(C-(Cz+Co))
Zp = Lc * cos(B-(Bz+Bo))
Bz,Cz : B-axis and C-axis origin compensation values
Bo,Co : B-axis and C-axis rotation axis offset values
NOTE
Even in three-dimensional handle feed/interrupt,
rotation axis origin compensation and rotation axis
offset can be used. Note, however, that a
compensation vector for tool axis direction tool length
compensation is calculated using absolute
coordinates, while machine coordinates are used for
three-dimensional handle feed/interrupt. This means
that, if there is a mismatch between the absolute
coordinates and machine coordinates, a different
compensation calculation result is produced by each
function. So, when using three-dimensional handle
feed/interrupt together with tool axis direction tool
length compensation, ensure that the machine
coordinates and absolute coordinates match.
Limitation
- Automatic reference position return command (G28, G29, G30)
Never specify an automatic reference position return command (G28,
G29, or G30) in tool axis direction tool length compensation mode.
If an automatic reference position return command is specified in tool
axis direction tool length compensation mode, the compensation vector
is cancelled at the time of reference position return. So, correct tool
axis direction tool length compensation is not performed in subsequent
movement along linear axes.