RTC
®
5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
180
Correction via McBSP Interface
If position values for Processing-on-the-fly correction
are forwarded via the McBSP interface, then
Processing-on-the-fly correction must be activated
via set_fly_x_pos and/or set_fly_y_pos. Here, the
scaling factor [in bits per bits] defines the relation
between the shift [in bits] of the current output
position in the image field and the input value [in
bits] at the McBSP interface (see below).
Thereafter, the output value is calculated from the
current output position by adding (for each direction)
the product of the scaling factor and the current
input value at the McBSP interface. This correction is
performed every 10 µs.
For one-dimensional correction, the McBSP interface
provides a (signed) 32-bit value. For two dimensions,
in contrast, the position values of the two axes can
only be forwarded via a (signed) 16-bit value, each.
Here, the X axis gets the lower 16 bits and the Y axis
gets the upper 16 bits of the value at the McBSP
interface. For a description of the interface, see
page 52.
Determining Scaling Factors
If workpiece or scan system position is to be regis-
tered via the McBSP interface, then a calibration
procedure will be required to determine the scaling
factor:
First, the command read_mcbsp must be used to
determine the position increments i
x
and i
y
[in bits
per mm] for each direction:
Read the start input value (via read_mcbsp) and
begin the movement
Stop the movement and read the end input value
(via read_mcbsp)
Measure the distance travelled in mm
The position increment i can then be calculated as
follows:
i = (end input value – start input value) /
distance travelled
In a second step, the scaling factors
Scale
x
and
Scale
y
[in bits per bits] can be calculated from the
determined position increments as follows:
Scale
x
= K / i
x
Scale
y
= K / i
y
whereby K is the calibration factor [in bits per mm]
(see page 119).
Notes
•After set_fly_x_pos and set_fly_y_pos, the input
values received at the McBSP interface automati-
cally get copied to internal memory location 0.
This still applies even after Processing-on-the-fly
correction gets switched off via fly_return,
set_fly_x_pos, set_fly_y_pos or
set_fly_rot_pos, as well as after a reset via
load_program_file. The current data at memory
location 0 can be queried via
read_mcbsp(0)
.
• In contrast, activation of Processing-on-the-fly
correction via set_mcbsp_in or
set_mcbsp_in_list might also result in McBSP
input values being copied to internal memory
locations 1, 2 and/or 3 (see page 181). If online
positioning is activated, then they will be copied
to internal memory location 1 or possibly 2 (but
not to memory locations 0 or 3) (see page 165).
• After Processing-on-the-fly correction is activated
via set_multi_mcbsp_in or
set_multi_mcbsp_in_list, the transmitted data
will get consecutively written to memory
locations 0 through 3. You can also query it from
there (unsorted) with read_mcbsp.
To Next Page
Loading...
