Correction Via Mcbsp Interface - Scanlab RTC 5 PC Interface Board Installation And Operation Manual

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
determine the position increments i
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
[in bits per bits] can be calculated from the
Scale
y
determined position increments as follows:
= K / i
Scale
x
x
= K / i
Scale
y
y
whereby K is the calibration factor [in bits per mm]
(see page 119).
®
RTC 5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
Notes
• After
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_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_list
input values being copied to internal memory
locations 1, 2 and/or 3 (see
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
• After Processing-on-the-fly correction is activated
via
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.
must be used to
and i [in bits
x y
and
x
set_fly_x_pos and set_fly_y_pos, the input
set_fly_y_pos
set_mcbsp_in or
might also result in McBSP
page
set_multi_mcbsp_in or
or
181). If online
page 165).
180