Chapter
6
Operating Instructions
CLV 490 Bar Code Scanner
6-12
©
SICK AG · Division Auto Ident · Germany · All rights reserved
8 009 993/O824/20-12-2004
Operation
Autofocus
Condition: Reading from above
•
Minimum distance:
Relative to its surroundings, the object is always located at the shortest distance from
the CLV. Example: object positioned directly on the conveyor belt without a container
(tray, etc.) or interfering side boundaries
Condition: only
one object
in the reading field during the reading interval.
•
Differential background:
The background can be closer to the CLV than the object.
Example: object in a container on the conveyor belt; the container wall is higher than
the object (closer to the CLV).
Condition: only
one object
in the reading field during the reading interval.
•
Differential background and tracking:
Same as the "Differential background" function, except that in each reading pulse
more
than one object
can be located in the reading field at the same time. On the basis of
the detected distances, the CLV assigns the required focus positions in its internal focus
list to the objects and organizes the objects using a continuous increment in its object
list. In this way, scanned bar-code information can be uniquely assigned to the individual
objects. This is only available in the reading mode "Tracking" (internal tracking or
reading mode "OTS trigger"), not in "Object polling" mode (one object only) of start/stop
mode. For more detailed information, see also
Chapter A2. Tracking mode (controlled
Explanation
Background teach-in:
For autofocus modes "Differential background" and "Differential background and tracking",
the CLV can also teach in the ambient background in its area of view (e.g. if interfering
objects in the conveyor system project into the defined autofocus area) in order to improve
the evaluation of the current distance profile. When doing so, the CLV adjusts – among other
things – the measured background by 100 mm (3.9 in) in its direction to compensate any
measurement inaccuracies.
The default background at a distance of 2,200 mm (86.7 in) is used in all other cases and,
if necessary, the autofocus area is limited by means of the appropriate parameters. In this
case, CLV measurement inaccuracies must be taken into account when the rectangular
autofocus space is defined (see note
.
Action
Settings in CLV-Setup
Activate autofocus
–
or
–
Ö
R
EADING
C
ONFIGURATION
tab
Ö
F
OCUS
C
ONTROL
section
– Autofocus
Activate focus position switch-
over (event-controlled)
(selecting trigger source)
Ö
R
EADING
C
ONFIGURATION
tab
Ö
F
OCUS
C
ONTROL
section
– Inputs/Serial
or
– Timer
Ö
T
IMER
or
– Static/No trigger
Oscillating mirror:
– additionally: Oscillating mirror extrema
Table 6-5: Guide: Selecting the focus control mode
c) Parameterizing focus control