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Operating Instructions
Chapter
3
CLV490 Bar Code Scanner
8009993/RA61/2007-07-20
©
SICK AG · Division Auto Ident · Germany · All rights reserved
3-9
Product description
command strings via the data interface or can be left free running. The CLV490 either out-
puts the reading result at the end of the reading pulse (the back edge of the object has left
the end of reading field) or already during the reading pulse as a result of predefined (pa-
rametrized) conditions. To separate bar codes of the same type with identical contents, an
incremental encoder must be connected to the CLV490.
In object polling mode, the CLV490 automatically detects the beginning and the end of the
object located in the reading field without any help of external sensors. The minimum tem-
poral distance between two consecutive objetcs must not fall below 70 ms when the ob-
jects are moved on the conveyor belt.
Tracking mode
During the reading process,
max. 10 objects
can simultaneously be located in the reading
field (following each other)(
). As default, a reading pulse sensor at the beginning of
the reading field controls the starting of the reading process. The end of the reading field is
determined by the parametrized object release point in the CLV490. In this way, the size of
the reading field is clearly determined.
In order to track the transport of the objects in the reading field, a regularly-timed pulse is
required. This is generated by an external incremental encoder which regularly supplies a
pulse at least every 10 mm (0.39 in) of movement in conveying direction. As a result, the
the distance between the reading pulse sensor and the object release point is clearly time-
mapped in the CLV490. Fluctuations when approaching the conveyor or decreases in speed
due to heavy load with numerous conveyor obejcts are also recorded. An internal clock in
the CLV490 also allows operation at a constant conveyor speed. A gap of at least 50 mm
(1.97 in) is necessary for the clear separation of consecutive objects. The reading result for
an object is output after the back edge of the object passes the object release point. Alter-
natively, the reading process can be started with a command strings via the data interface.
Fig. 3-5:
Reading modes of the CLV490 in stand-alone configuration
3.2.4
Scan procedure variants
Line scanner (standard device)
Generates a scan line; due to the V-principle of the beam generation, the reading field height
(the useful length of the scan line for evaluation purposes) is dependent on the reading
distance.
Start/stop mode
Tracking mode
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