Rockwell Automation 2755 Enhanced Decoder Series B - Manual (Page 95)

7–7 Configuration: Scanner Control, Primary Match Table, Discrete I/O
Publication 2755-833
The decoder interprets a scanned label in one of three ways.
•
Valid Scan
Sufficient valid symbols have been decoded to satisfy the
Symbols/Scan parameter.
•
Undecodable Scan
The scanned data does not correspond to a valid pattern within
the selected symbologies.
•
Misread or Substitution Error
Smudges, stray marks, voids, or print errors (resulting in wider or
narrower bars and spaces) may result in a pattern that is valid
within an enabled symbology that is not representative of the
intended data.
The capture count reduces misreads by requiring the decoder to read
labels multiple times before producing a valid read.
Symbologies that are not self-checking (do not use start and stop
characters or check characters) are more susceptible to misreads. For
example, Interleaved 2-of-5 without check characters is not
self-checking.
Setting the capture count too high may result in excessive no-reads,
particularly when the number of scans crossing the label in a trigger
period is low (5 - 10). Set the capture count to a value no greater than
half the number of expected scans crossing the label in a trigger
period.
Symbols / Scan
Field Type Options
Select/Edit
1–6, Any
1
Specifies the number of bar code symbols that must be present in a
scan for a valid read. The default is 1.
On a single scan (movement of laser beam from one side to another),
the decoder can decode up to 6 successive bar code symbols. Valid
settings for this parameter include 1, 2, 3, 4, 5, 6 or Any.
If you select Any, the decoder looks for up to 6 symbols. The
decoder will ignore any damaged symbols it encounters.
Select Any for those applications where the number of symbols
varies or cannot be controlled. For all other applications specify a
number.