Chapter
10
Operating Instructions
CLV 490 Bar Code Scanner
10-88
©
SICK AG · Division Auto Ident · Germany · All rights reserved
8 009 993/O824/20-12-2004
Appendix
Percentage evaluation
Special operating mode in which the quality of the reads (not those of the bar codes, how-
ever) is assessed statistically. The bar codes must be stationary. The CLV carries out 100
scans and evaluates the reading quality. It then outputs the reading results on the
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termi-
nal interface every 2 s together with the
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reading diagnosis data.
Plain text
Legible form of a CLV message. The CLV outputs special messages in coded form, e. g. the
result of the self-test is represented as three digits.
Reading diagnosis data
Data directly derived from the reading procedure by the CLV. This data enables the quality
of the read to be assessed. The data is always output on the
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terminal interface together
with the reading result. Only output on the host interface if enabled on the D
ATA
S
TRING
tab
in the "CLV-Setup" program (for the CLV 490 disabled by default).
Reading field
In start/stop mode the reading field is the area between the start and stopp sensors for the
reading pulse in conveyor direction. In tracking mode the reading field is the area between
the sensor for start/end of an object and the object release point (data output) (parameter-
ized as a distance in conveyor direction), referred to the increments.
Reading field height
Length of the
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scan line that is available for detecting the bar code in the reading plane.
Due to the V-principle of beam generation, the reading field height is dependent on the
reading distance.
Reading interval
Timeslot in which the CLV activates the laser diode and attempts to detect valid bar codes
from the information read. The reading interval may be shorter than the external reading
pulse, depending on the selected output mode for the reading result.
Reading pulse
Clock pulse applied externally to the CLV to trigger the internal
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reading interval. Can be
supplied by a photoelectric reflex switch or a command from the host on the serial inter-
face.
Reading range (DOF)
Depth of field about the focal point of the laser beam on two sides. The extent of the reading
range depends on the resolution and reading distance.
Reading result
Electronic representation of the data content of the read bar code together with the
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read-
ing diagnosis data in one
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data output string that is generated after the reading pulse has
elapsed. The reading result on the terminal interface has a fixed format (content and output
format); the reading result on the host interface can be configured separately for Good
Reads and No Reads. Special characters can also be added if necessary.