Scanlab RTC 5 PC Interface Board, Installation And Operation Manual

Page: 141 / 622

RTC
®
5 PC Interface Board
Rev. 1.9 e
7 Basic Functions for Scan Head and Laser Control
141
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For position-dependent and speed-dependent or
encoder-speed-dependent laser control, only a
common signal parameter selection can be defined.
Thus, these corrections are applied to the same signal
parameter. In contrast, a different signal parameter
can be selected for vector-dependent laser control.
The automatically readjusted final output values for
laser control can be logged via
set_trigger / set_trigger4 (
Signal1/2
=24 and
31…38). This allows, for example, monitoring the
effect of varying speed during acceleration or decel-
eration phases of the scanner motion.
Notes
• A varying laser impact resulting from an explicit
change of the marking speed between to
marking commands (by calling
set_mark_speed )
will not be compensated by automatic laser
control.
• If automatic laser control readjusts the 12-bit
output values at the ANALOG OUT1 or
ANALOG OUT2 output ports or pulse lengths
(
PulseLength
) or output periods (
HalfPeriod
) of
the laser signals LASER1 and LASER2, then
automatic laser control should
not be used in
conjunction with the pixel output or softstart
modes (these functions cause mutual disruption).
In contrast, automatic readjustment of values
output at the 16-bit or 8-bit digital output ports
can be used simultaneously and unrestrictedly
with the pixel output or softstart modes.
• The user is responsible for determining the
automatic laser control parameter settings and
tables necessary for their applications. This can
require considerable effort, but it is recom-
mended especially if exceptionally high precision
is needed.
• Automatic laser control can’t be combined with
variable laser control via the McBSP interface (see
set_multi_mcbsp_in
).
Position-Dependent Laser Control
To initialize position-dependent laser control,
set_auto_laser_control must be used for specifying
which signal parameter will be readjusted (via the
Ctrl
parameter), and the load_position_control
command used for loading a scaling function.
For subsequent mark and arc commands (also timed
mark commands), the RTC
®
5 will then perform an
automatic position-dependent correction of the
selected signal parameter (i.e. a correction
dependent on the radial distance between the
current output position and the image field center).
The selected signal parameter is multiplied by the
position-dependent (radial) correction factor defined
via the loaded scaling function. The scaling factors
are relative to a 100% value defined via the
set_auto_laser_control command (
Value
parameter).
Because position-dependent changes in laser impact
are system dependent, the to-be-loaded scaling
function must be defined by the user in a text file (see
"Notes on Loading a Scaling Function", page 143 ).
Position-dependent compensation is calculated
based on the current cartesian control values
Sample<X..Y>
(also see set_trigger / set_trigger4 ).
Where applicable, these encompass wobbel and
Processing-on-the-fly corrections, but not image field
corrections, coordinate transformations or gain and
offset corrections.
General Notes
• set_auto_laser_control (
Ctrl
parameter) allows
initialization of not only position-dependent, but
also speed-dependent or encoder-speed-
dependent laser control (see
page 146 and
page 148 ). The signal parameter selection and
the 100% value defined via
set_auto_laser_control (
Ctrl
and
Value
param-
eters) apply to both corrections and the
correction factors for position- and speed-
dependent or encoder-speed-dependent laser
control will then be multiplicably combined into a
common factor.
If only position-dependent laser control is
required, then speed-dependent or encoder-
speed-dependent laser control can be deacti-
vated via
set_auto_laser_control (parameter
Mode=0
).
In contrast, if only speed-dependent or encoder-
speed-dependent laser control is required, then
position-dependent correction can be effectively