Requirements For Codes And Legibility; What Is Required Of Data Matrix And Vericodes - Siemens SIMATIC Vision Sensor VS 130-2 Manual

1.7

Requirements for Codes and Legibility

1.7.1

What is Required of Data Matrix and Vericodes?

General Requirements for Data Matrix and Vericodes to Ensure Readability
VS 130-2 can read data matrix codes with properties corresponding to those
published in the standard for data matrix codes. In many ways, VS 130-2 reacts
tolerantly even when certain basic properties are absent and is capable of dealing
with difficulties that are not specified in the standard.
As a result, VS 130-2 and VS 130-2vcr have a very wide range of application in
normal situations, a fact reflected in the following broad limits:
•
It can read codes in which directly adjacent code points have a minimum
distance of only 5 pixels and up to a maximum distance of 35 pixels.
• The deviation of the sensor axis from the vertical can be between 0 ° und 40 °.
•
The code field can approach the edge of the image up to a distance equivalent
to twice the code point diameter.
•
The dominant polarity of the code points compared with the background is
required uniformly for all points (as it was during the training procedure). Slight
shadows or shiny areas are tolerated.
•
The ratio of the distance to the closest neighbor and the diameter of any code
point can be between 2 and 0.8.
•
Although code points must be printed according to a regular square grid
pattern, individual points can be displaced from their ideal position by up to 1/3
of the grid unit. Even slight parallelogram-shaped distortion is tolerated.
•
With large-image but small-dimensioned codes, slight curves in the printed
material surface are tolerated. With high-value codes (for example, more than
14 x 14) or a strongly inclined sensor axis, curves are not allowed.
•
Large tolerance of background disturbances that cannot be described
quantitatively
•
Large tolerance of poor contrast conditions
•
Due to the limited image resolution, codes with a maximum code dimension of
72x72 can be read.
In terms of these limit characteristics and when using minimum read rates due to
the requirements of the application (can be set with the "Cycletimelimit" parameter)
the tolerances are generally restricted, in some cases in stages, or other conditions
come into play. The limits described below are intended mainly as guidelines since
the actual conditions in a real application cannot be assessed accurately in
advance. It is therefore conceivable that higher read rates can be achieved even if
individual conditions are not fully adhered to.
Vision Sensor SIMATIC VS 130-2/VS 130-2vcr
A5E00475759-01
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