Siemens SINUMERIK 840D sl Function Manual page 543

$AA_IBC[ <axis>]
The variable $AA_IBC[ax] determines the setpoint position of a cartesian axis lying between
BCS and MCS. If an axis is cartesian at the output of the nth transformation, then this output
value is delivered. If the corresponding axis at the output of all transformations is not
cartesian, then the BCS value including all BCS offsets of the axis are determined.
If TRACON responds to an axis as cartesian, then its MCS value is delivered. The used axis
identifier can be a geometrical-, channel- or a machine axis identifier.
$VA_ITR[ <axis>, <transformer layer> ]
The variable $VA_ITR[ax,n] determines the encoder position of an axis at the output of the
nth chained transformation.
$VA_IBC[ <axis>]
The variable $VA_IBC[ax] determines the encoder position of a cartesian axis lying between
BCS and MCS. The used axis identifier can be a geometrical-, channel- or a machine axis
identifier.
If an axis at the output of the nth transformation is cartesian, then this output value is
delivered. If the corresponding axis at the output of all transformations is not cartesian, then
the BCS value of the axis is determined.
$VA_IW[ <axis>]
The variable $VA_IW[ax] determines the encoder position of an inverse-transformed axis in
WCS. The WCS value contains all axis-related superimposition portions (DRF, AA_OFF, ext.
zero offset etc.) and offset values (CEC, etc.).
$VA_IB[ <axis>]
The variable $VA_IB[ax] determines the inverse-transformed encoder position of an axis in
BCS. The BCS value contains all axis-related superimposition portions (DRF, AA_OFF, ext.
zero offset etc.) and offset values (CEC, etc.).
Note
$VA_ITR$, VA_IBC, $VA_IW, $VA_IB
The value of the a variable does not change while reading the variable within an IPO cycle,
although the actual value could have changed.
In active transformations, one must consider that the transformation of the actual values into
BCS in the IPO cycle can be very time-consuming. In this case one must set an adequate
IPO cycle.
Extended Functions
Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Kinematic Transformation (M1)
7.5 Chained transformations
543