Siemens SIMATIC MV500, Руководство по эксплуатации, Страница: 40 / 294

Image processing
3.1 Code reading (1D/2D codes)
SIMATIC MV500
40
Operating Instructions, 03/2021, C79000-G8976-C494-05
The recognition process of the optical reader allows reliable and fast reading of printed QR
codes of good quality.
Range of application
• The range of imaging sizes ranges from 5 to 35 pixels per cell. The range is static.
• The codes can have any alignment in the image.
• The code can be printed both dark on a light background and light on a dark background.
• The viewing angle of the optical reader to the surface can be between 70° and 90°.
• The diameter of the cells must be uniform over the entire code field.
• The contrast between cells and the background must be approximately the same over the
entire code field.
• The image background must have a homogeneous brightness, for example no texture
such as stripes.
3.1.2.4 PDF417 codes
Note
Unsupported code types
The following code types are not supported: Truncated PDF417, Macro PDF417, Micro
PDF417.
The recognition process of the optical reader allows reliable and fast reading of printed
PDF417 codes of good quality.
Range of application
• The codes can have any alignment in the image.
• The code can be printed both dark on a light background and light on a dark background.
• Codes with a bar width ≥ 3 pixels and in which the height of a single row of symbols is ≥ 9
pixels can be read.
• The width of the black and white bars must be uniform over the entire code field.
• The viewing angle of the sensor to the surface can be between 70° and 90°.
• The code should not make contact with any other objects in the image, you can do this,
for example by keeping the quiet zone free with twice the column width.
• Within the code, the ratio of contrast (in other words, the difference between black and
white) to noise should be at least three. This ratio must be similar over the entire code
field.
• The image background must have a homogeneous brightness, for example no texture
such as stripes.