Printronix PrintNet Enterprise - Manual (Page 292)

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Chapter 7 Data Validation
• Percent Decode: This is a measure of consistency throughout the height
of the bar code which indicates the number of good scans as a
percentage of total scans. This is usually an indication of large blemishes
within the code, such as with a wrinkle.
• Quiet Zone: This occurs when the minimum blank zone surrounding the
bar code has not been met. This can typically occur in poorly designed
forms where bar codes are placed too close to other elements, or the bar
code is too close to an edge of the media, or the position of the media is
shifting.
• (Symbol) Contrast: This occurs when the contrast between bars and
spaces is not sufficient. This can be due to excessively light printing from
too little heat on the printhead. It is also caused by colored media or
ribbons.
• Modulation: This occurs when the ratio of the Minimum Edge Contrast
and Symbol Contrast is below 40%.
• Minimum Reflectance: This occurs when the reflectance value for at
least one bar in a bar code is not half or less than the highest reflectance
value for a space.
• Minimum Edge Contrast: This error occurs when the Minimum Edge
Contrast value is less than 15%.
In a bar code, each transition from a space to a bar (or a bar to a space) is
an edge whose contrast is the difference between the peak values in the
space and bar reflectance. Each edge in the bar code is measured, and
the edge that has the minimum contrast is the Minimum Edge Contrast.
It is possible that more than one failure message can be reported in a bar
code report. However, the printer can display only one error message at a
time. Thus, when multiple failures are detected, only one message displays
and the rest are ignored, based on the following failure priority hierarchy.
Priority Failure Message
Operator Panel
Message
1
(highest)
Encodation Bar code improper
data format
2 Checksum Checksum Failure
3 Quiet Zone Bar code quiet
zone too small
4 (Symbol) Contrast Contrast too low
Check media
5 Percent Decode Poor scanning
Check media
6 Defects Poor scanning
Inspect head