Commissioning
English, Revision 06, Date: 12.07.2011
12
The code ends with a bold line followed by a narrow space and a narrow line. Due to
these different codings it is not important whether the code is read “normal“ or “upside
down“. So the decoding is not connected to the driving direction.
Furthermore there have to be so called rest zones in front of the first and behind the
last line. A code check is not provided as the label would have to be two times as bold.
2.6.2
Width of the barcode label
The minimal width of the module (this means the width of a narrow line or space) de-
pends on the reading distance and the resolution of the camera. The minimal module
width of the camera G_73841 at 100mm reading distance is 1mm. So the smallest la-
bel measures 26mm from the beginning of the first line to the end of the last line.
Further geometrical facts of the code label:
-
the boldest line or space cannot be bolder than 1/3 of the parametrized
track width
-
the rest zones in front of and behind the code have to be bolder than 1/8 of
the parametrized track width
-
the smaller the module (width if lines) the more sensitive the interpreter
reacts to no or a wrong decoding
The barcode shown in picture 1 has a module width of 1.55 mm (31mm code width).
2.6.3
Length of the barcode label
It is necessary to assure that the label is at least for the duration of on picture (20ms)
within the lens coverage. So the length of the label is determined by:
L [mm] > 20ms x Vmax [mm / ms]
2.6.4
Inverse track
If the interpreter is parametrized to inverse track (light track on dark ground) the bar-
code also has to be inverted.
2.6.5
Position
In general, the label can be located practically everywhere in the field of view. Only
two things have to be taken in consideration:
-
there can only be one label. If there are more than one label, only the left
label in driving direction will be interpreted
-
the label may be detected as track, so it is recommended to place the label
directly upon the track
