Siemens SINUMERIK 840D sl Programming Manual page 738

Work preparation
3.12 Transformation with kinematic chains
Point to close the tool chain
If the $NT_CLOSE_CHAIN_T system variable is not empty, the tool chain is not closed at the
end point of the chain, but rather at the end point of the designated chain element. Other chain
elements that are behind this point result in a corresponding work offset when the
transformation is activated.
Index of an orientation axis
In addition to the constants offsets between the orientation axes, the direction vectors of the
orientation axes can also be written with the CORRTRAFO function. The index of an orientation
axis is the index that results when the kinematic subchain is run through from the origin to the
end, where the count starts at zero. The index of an orientation axis is therefore always the
same as the index of the preceding section.
The index of an orientation axis can also be determined with the $AC_TRAFO_ORIAX_LOC
system variable.
Maximum permissible change of a chain element
The maximum permissible change of a chain element can be limited by the two setting data
SD41610 $SN_CORR_TRAFO_LIN_MAX for offset vectors and SD41611
$SN_CORR_TRAFO_DIR_MAX for direction vectors of the orientation axes. SD41610
$SN_CORR_TRAFO_LIN_MAX specifies the maximum amount by which each individual
vector component can be changed with regard to its reference value. SD41611
$SN_CORR_TRAFO_DIR_MAX specifies the maximum angle by which the direction of the
axis vector can be changed with regard to its reference value. The reference value is always the
corresponding value that is active in the transformation that is active when CORRTRAFO is
called. This means that the changed content of the kinematic data may have no effect on the
method of operation of the CORRTRAFO function after the activation of the transformation.
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Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming