Siemens SINUMERIK 840D sl Function Manual page 1908

Detailed Description
2.5 Toolholder with orientation capability
Rotary axis offset
Rotary axis offsets can be specified with system variables $TC_CARR24 and $TC_CARR25.
A value not equal to zero in one of these parameters means that the initial state of the
associated rotary axis is the position specified by the parameter (and not position zero). All
angle specifications then refer to the coordinate system displaced by this value.
When the machining plane is changed (G17 - G19), only the tool length components of the
active tool are interchanged. The components of the toolholder are not interchanged. The
resulting tool length vector is then rotated in accordance with the current toolholder and, if
necessary, modified by the offsets belonging to the toolholder.
The two toolholder angles α
plane currently selected (G17 - G19).
Limit values
Limit angles (software limits) can be specified for each rotary axis in the system variable set
($TC_CARR30 to $TC_CARR33) used to describe the toolholder with orientation capability.
These limits are not evaluated if both the minimum and maximum value is zero.
If at least one of the two limits is not equal to zero, the system checks whether the previously
calculated solution is within the permissible limits. If this is not the case, an initial attempt is
made to reach a valid setting by adding or subtracting multiples of 360 degrees to or from
the invalid axis position. If this is impossible and two different solutions exist, the first solution
is discarded and the second solution is used. The second solution is treated the same as the
first with reference to the axis limits.
If the first solution is discarded and the second used instead, the contents of $P_TCANG[1/2]
and $P_TCANG[3/4] are swapped, hence the solution actually used is also stored in
$P_TCANG[1/2] in this case.
The axis limits are monitored even if the axis angle is specified instead of being calculated.
This is the case if TCOABS is active when a toolholder with orientation capability is activated.
120
and α are determined using a frame, independent of the active
1 2
Basic logic functions: Tool Offset (W1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0