Siemens SINUMERIK 840D sl Programming Manual page 570

Path traversing behavior
8.8 Programmable contour/orientation tolerance (CTOL, OTOL, ATOL)
Note
If no tolerance values have been programmed, the $A variables will not be differentiated
sufficiently to distinguish potential differences in the tolerances of the individual functions,
since they can only declare one value.
Circumstances like this can occur if the machine data and the setting data set different
tolerances for compressor functions, smoothing and orientation smoothing. The variables
then return the greatest value prevailing with regard to the currently active functions.
if, for example, 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, only the value "0.1" will remain to be read.
● Without preprocessing stop in the part program via system variables:
Note
If no tolerance values have been programmed, the $P variables will return the value "-1".
570
$P_CTOL Programmed contour tolerance
$P_OTOL Programmed orientation tolerance
$PA_ATOL Programmed axis tolerance
Programming Manual, 06/2009, 6FC5398-2BP20-0BA0
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