Rockwell Automation 2755 AdaptaScan Software - Manual (Page 46)

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Publication 2755-838
Margin
The scanner metric for margin is a measure of how clearly
distinguishable the different element sizes (bars and spaces) are in a
symbol. Margin is calculated every time a symbol is decoded. The
margin result is the tolerance remaining before the AdaptaScan can
no longer differentiate between wide and narrow elements.
Several factors affect the margin, including how well the
AdaptaScan is focused and the quality of the symbol. Assuming that
the AdaptaScan is properly focused, margin can be used for an
indication of trends in label quality. This is especially true for ink jet
symbols on cardboard cartons where low margins can occur because
of increasing ink spread.
Margin values may be returned in a host message (see page 10–2) or
used to trigger an output if the margin value falls below a user
defined level (see page 7–8).