System Variables - Siemens SINUMERIK 840D sl Function Manual

M1: Kinematic transformation
7.4 Chained transformations
Supplementary conditions
The supplementary conditions and special cases indicated in the individual transformation
descriptions are also applicable for use in chained transformations.
Tool data
A tool is always assigned to the first transformation in a chain. The subsequent transformation
then behaves as if the active tool length were zero. Only the basic tool lengths set in the
machine data (_BASE_TOOL_) are valid for the first transformation in the chain.
7.4.1.2

System variables

System variables having the following content are provided for machines with system or OEM
transformations, especially for chained transformations (TRACON):
Type
REAL
REAL
REAL
REAL
REAL
REAL
The following must be observed with reference to the control system responses:
● POWER ON
The encoder position has the value 0 for not-referenced axes. The encoder actual values
are inverse-transformed accordingly for the $VA variables.
● RESET
An active transformation can change in RESET, which has a direct influence on the values
of the system variables. An active transformation which is active again after RESET, is
deactivated for a short duration and then reactivated. This has a direct influence on the
position variables. The values of variables can change.
Via the variable:
$AC_STAT == 0
this status can be queried in synchronous actions.
446
System variable Meaning
$AA_ITR[ax,n] Current setpoint value at output of the nth transformation
$AA_IBC[ax] Current setpoint value of a cartesian axis
$VA_ITR[ax,n] Current actual value at output of the nth transformation
$VA_IBC[ax] Current cartesian BCS encoder position of an axis
$VA_IW[ax] Current WCS actual value of an axis
$VA_IB[ax] Current BCS encoder position of an axis
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
Extended Functions