Siemens SINUMERIK 840D sl Function Manual page 234

B1: Continuous-path mode, Exact stop, Look Ahead
4.6 Contour/Orientation tolerance
System variables
Reading with preprocessing stop
Via the following system variables, the currently active tolerances can be read in the NC part
program and synchronized action:
● $AC_CTOL
Channel-specific contour tolerance effective when the current main run record was
preprocessed.
If no contour tolerance is effective, $AC_CTOL will return the root of the sum of the squares
of the tolerances of the geometry axes.
● $AC_OTOL
Channel-specific orientation tolerance effective when the current main run record was
preprocessed.
If no orientation tolerance is effective, $AC_OTOL will return the root of the sum of the
squares of the tolerances of the orientation axes during active orientation transformation.
Otherwise, it will return the value "-1."
● $AA_ATOL[<axis>]
Axis-specific contour tolerance effective when the current main run record was
preprocessed.
If no contour tolerance is active, $AA_ATOL[<geometry axis>] returns the contour tolerance
divided by the root of the number of geometry axes.
If an orientation tolerance and an orientation transformation are active
$AA_ATOL[<orientation axis>] will return the orientation tolerance divided by the root of
the number of orientation axes.
Note
If now tolerance values have been programmed, the $A variables are not differentiated enough
to distinguish the tolerance of the individual functions.
Circumstances like this can occur if the machine data and the setting data set different
tolerances for compressor functions, smoothing and orientation smoothing. The system
variables then return the greatest value occurring with the functions that are currently active.
For example, if a compressor function is active with an orientation tolerance of 0.1° and
ORISON orientation smoothing with 1°, the $AC_OTOL variable will return the value "1." If
orientation smoothing is deactivated, $AC_OTOL will return the value "0.1."
Reading without preprocessing stop
Via the following system variables, the currently active tolerances can be read in the NC part
program:
● $P_CTOL
Currently active channel-specific contour tolerance.
● $P_OTOL
Currently active channel-specific orientation tolerance.
● $PA_ATOL
Currently active axis-specific contour tolerance.
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Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions