Block Change Behavior With Active Coupling (Cpbc) - Siemens SINUMERIK 840D sl Programming Manual

Work preparation
3.14 Path traversing behavior
Reading without preprocessing stop
Using the following system variables, the currently active tolerances can be read in the 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.
Supplementary conditions
The tolerances programmed with CTOL, OTOL and ATOL also affect functions that indirectly
depend on these tolerances:
● Limiting the chord error in the setpoint value calculation
● The basic functions of the free-form surface mode
The following smoothing functions are not affected by the programming of CTOL, OTOL and
ATOL:
● Smoothing the orientation with OSD
OSD does not use a tolerance, it uses a distance from the block transition.
● Smoothing with G644
G644 is not used for smoothing, it is used for optimizing tool changes and other motion not
involving machining.
● Smoothing with G645
G645 virtually always behaves like G642 and, thus, uses the programmed tolerances. The
tolerance value from machine data MD33120 $MA_PATH_TRANS_POS_TOL is only used
in uniformly tangential block transitions with a jump in curvature, e.g. a tangential circle/
straight line transition. The rounding path at these points may also be located outside the
programmed contour, where many applications are less tolerant. Furthermore, it generally
takes a small, fixed tolerance to compensate for the sort of changes in curvature which need
not concern the NC programmer.
3.14.11

Block change behavior with active coupling (CPBC)

The CPBC command specifies the block change criterion that must be satisfied so that a block
change can be executed in the part program with active coupling.
Syntax
CPBC[<following axis>] = <criterion>
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Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming