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Image processing
4.2 Code verification
4.2.6
Calibration and activating verification
Calibrate
To be able to use the reader as a verifier, a calibration consisting of the following two steps
must be performed:
1. System normalization,
2. Reflectance calibration.
Calibrating the reader ensures that with every test setup, correct and reproducible results are
returned in keeping with the selected standard.
● You will need to calibrate the reader the first time you commission it in your production
area.
Calibration library
Calibrations are created as elements in the verification library according to the procedure
described below (Normalizing the reader (Page 63)/Calibrating the reflectance (Page 64)).
Then, you can reference a stored calibration in one or more programs..
There must be stable lighting conditions
The conditions must be stable in the operating environment of the verifier. If the position of
the device or the ambient lighting or ambient temperature changes, recalibration is
necessary. Without calibration, the results may fluctuate considerably.
Regular recalibration it is necessary for stable results:
● If for example, you perform a verification once with high surrounding brightness and
another time with very low surrounding brightness.
After successful recalibration of an element of the verification library, all programs that
reference this element can be used immediately.
Siemens AG recommends that you operate the reader with its own lighting. You should also
shield the reader and the code to be measured from the surrounding light.
Normalizing system and calibrating the reflectance
The reader is supplied with a calibration card; see chapter Calibration card (Page 391).
Once you have set up the reader in the location where it will be used, the system needs to
be normalized and the reflectance calibrated with the calibration card. The reflectance
calibration specifies the correct calculation of the contrast and the size measurements of the
test system.
62
SIMATIC MV420 / SIMATIC MV440
Operating Instructions, 04/2013, A5E02371045-06
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