RTC
®
5 PC Interface Board
Rev. 1.9 e
7 Basic Functions for Scan Head and Laser Control
114
Sky Writing mode 2 activation affects the same
commands as Sky Writing mode 1 (except ellipse
commands, see above). Time-optimized Sky Writing,
however, can only occur within a sequence of non-
parameterized mark, arc and jump commands (may
also contain timed or 3D commands). If such a
sequence gets interrupted by some other “non-Sky-
Writing2-capable” list command (e.g. a para, ellipse
or any short list command), then the RTC
®
5 will
suspend Sky Writing mode 2 and complete the
preceding command in Sky Writing mode 1 (with a
scanner retrace motion if required). This suspension
of Sky Writing mode 2 does not deactivate it (that
can only occur via set_sky_writing or
set_sky_writing_mode_list): Subsequent
“SkyWriting2 capable” commands will again execute
in Sky Writing mode 2 (however, the first command
of such a subsequent “SkyWriting2 capable”
sequence will execute in Sky Writing mode 1, i.e.
possibly with a scanner forerun motion).
With Sky Writing mode 2 activated, ellipse
commands are always fully executed in Sky Writing
mode 1.
Mode 3
The time cost of Sky Writing motions for vectors and
arcs having only small directional changes within a
polygonal traversal is probably disproportionately
high for the gained accuracy. To optimize Sky Writing
even in this scenario (for reducing total process time),
the RTC
®
5 provides Sky Writing Mode 3, which
allows specification of a switching limit (
Limit
) via
set_sky_writing_limit or
set_sky_writing_limit_list. After activation of Sky
Writing Mode 3 (via set_sky_writing_mode or
set_sky_writing_mode_list), Sky Writing motions
similar to Sky Writing Mode 2 will (only) occur for
large angular changes between consecutive vectors
or arcs of a polygonal traversal (cos()<
Limit
). In
contrast, smaller angular changes (cos()
Limit
)
will result in a possibly variable polygonal delay (see
page 104) instead of Sky Writing motion. Also see
figure 42.
Sky Writing Mode 3 produces a Sky Writing motion
before and after every polygonal traversal and also if
polygonal traversal is interrupted by non-Sky-
Writing2-capable” list commands (see the
description for Sky Writing Mode 2).
42
Sky Writing mode 2 Sky Writing mode 3
Legend
m executed with mark speed
j executed with jump speed
j
cos(f) ³ Limit
Jump
Mark
Mark
Jump
Arc
m
m
m
m
m
j
j
j
m
Jump
m
j
m
Jump
Arc
m
j
Mark
Mark
Arc
cos(f) ³ Limit
cos(f) < Limit
cos(f) < Limit
Jump
Mark
Mark
Jump
Arc
m
m
m
m
m
j
j
j
m
j
Jump
m
j
m
Jump
Arc
m
j
Mark
m
m
j
Mark
Arc
m
m
j
no Sky Writing
for small
changes of
direction
Sky Writing motions (grey) for Sky Writing modes 2 and 3
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