RTC
®
5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
165
innovators for industry
8.3 Online Positioning
The preceding chapter,
,
details how to precisely align a scan system relative to
the image field. The application program can, for
example, determine the required transformation
values by automatic position analysis for a workpiece
on a conveyer belt and then execute the associated
transformations.
However, it isn’t easy to achieve well-controlled
timing (referenced to the RTC
®
5’s 10
µ
s clock) while
positioning a workpiece and aligning the scan system
via the (control) commands described in the chapter
. For applications in
which such timing is important, the RTC
®
5 command
set also includes commands for so-called online posi-
tioning. Here, data for an offset and/or rotation coor-
dinate transformation or a general matrix operation
(e.g. directly from position analysis of the workpiece)
can be inputted via the McBSP interface.
The reading of online positioning data via the McBSP
interface needs to be activated and configured as
desired with the commands
,
and/or
commands) (see below). With
, you can acquire the most recent
fully transferred values and define the required coor-
dinate transformations (as with
or the equivalent list
commands). Here, as with the commands described
in the chapter
at_once
parameter can be used to specify when the
newly defined (total) transformation should take
effect.
For precise timing, execution of the list command
that triggers the transformation (depending on the
at_once
parameter, this would be
or any other list command)
can be made dependent on the input of an external
control signal (for conditional command execution,
see
The McBSP interface is described on
.
Configuring Online Positioning
The commands
and/or
(or the equivalent list commands)
determine both how the values inputted at the
McBSP interface will be interpreted by the RTC
®
5 and
which internal memory location will be used to read
the values:
• Depending on which of the above commands is
called, the RTC
®
5 will interpret the inputted
values as offsets in the X and/or Y directions
and/or as rotation values or as matrix coefficients.
The desired scaling factor always needs to be
supplied as a command parameter (except with
, see command description).
The three options
x
,
y
and
rot
can be used either
separately or in any desired combination. Via the
appropriate command, each option can be
enabled or disabled independently of the other
two. In contrast, the
matrix
option can’t be used
in conjunction with other options.
• As soon as one of the four options becomes
activated, all values subsequently inputted at the
McBSP interface will be internally stored in
memory location 1 or possibly memory location 2
(see below). Transferred values can subsequently
be queried via
or applied in
coordinate transformations via
or
.
•
x, y
or
rot
If you activate only
one
of the three options, then
X or Y offset correction values can be supplied as
signed
32-bit values or rotation correction values
as
unsigned
32-bit values.
The McBSP input values will be transferred to
internal memory location 1.
•
x and y (without rot)
If you activate X and Y offset corrections, but no
rotation correction, then the two offset
correction values must be supplied as a 16-bit
signed value, each, combined to a 32-bit value
(the X value in the lower 16 bits and the Y value
in the upper 16 bits).
The McBSP input values will be transferred to
internal memory location 1.
•
x or y and rot
If you activate an X or a Y offset correction
together with a rotation correction, then the
offset and rotation correction values should be
alternatingly supplied as 32-bit values. The
McBSP input values will then be alternatingly
