RTC
®
5 PC Interface Board
Rev. 1.9 e
8 Advanced Functions for Scan Head and Laser Control
185
After load_program_file, 2D encoder compensation
is inactive by default. It becomes active as soon as a
valid table from an ASCII-readable text file gets
loaded onto the RTC
®
5 board. You can subsequently
deactivate it by calling load_fly_2d_table using a
null pointer instead of the filename.
The following rules apply to the text file:
• The file can contain one or several tables, even
tables of other types.
• The 2D compensation table must begin with the
caption
[Fly2DTable<No>]
, whereby
<No>
corre-
sponds to the number supplied with the
load_fly_2d_table command.
• This is directly followed by a block of data points.
• If several tables with the same number exist, then
only data from the first encountered table will be
read. The others will be ignored.
• Reading of the text data terminates upon end of
file or upon a line containing a caption.
• All characters to the right of a semicolon are
treated as comments and ignored.
• The order of data points is up to you.
• The maximum length of a data line is 255
characters.
• A data line contains the two reference point
coordinates for Encoder0 and Encoder1 (signed
integers) and two compensation values (signed
integers), each separated by spaces or tabs:
<Encoder0> <Encoder1> <Encoder0-delta>
<Encoder1-delta>
• If a data point reoccurs, then the most recently
read value will be used; the others will be
ignored.
• Empty lines or incomplete data lines are invalid
and will be ignored.
Coordinate Transformations in the Virtual
Image Field
For set_fly_2d Processing-on-the-fly applications,
you can also define coordinate transformations in the
virtual image field. Such “virtual coordinate transfor-
mations” (particularly translations and rotations) are
sometimes needed to compensate certain
mechanical tolerances of object positioning when
performing continuous marking larger than the real
image field. Unlike other head-specific coordinate
transformations, the (possibly additional) virtual
coordinate transformations are applied to the entire
virtual image field before Processing-on-the-fly
correction.
You can define virtual coordinate transformations via
the commands set_matrix, set_offset and
set_offset_xyz (parameter
HeadNo
= 4). They let you
define matrix coefficients and offsets (however
set_offset_xyz will ignore
OffsetZ
). The data will be
cached on the board and applied for calculations
after the next set_fly_2d command. The parameter
at_once
has no significance if
HeadNo
= 4. While a
Processing-on-the-fly application is active, you can’t
change parameters for virtual coordinate transfor-
mation.
The range for offsets is ± 23 bits. Matrix coefficients
must not exceed an absolute value of 1.5. As with
head-specific transformations, the offset is applied
after the matrix operation.
You can’t use set_scale and set_angle or any coor-
dinate transformation list commands for virtual coor-
dinate transformations.
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