254764-001 Rev B 18
Picket Fence Bar Code Positioning Specifications:
•
Four codes across maximum
•
Horizontal gap between codes: .5 inch (13 mm) minimum
•
Maximum number of codes per sync period: 99
Ladder Direction
In ladder direction, one bar code at a time is usually in the beam. The amount of time the code is in the
beam is a function of the total width of the code (including quiet zone), the length of the beam area that is
used for scanning and the speed the code is travelling. The distance the bar code is in the beam is calculated
by subtracting the bar code width from the length of the beam programmed to scan the bar code. (See
Setting Ladder Mode Scanning Length Section below.) Divide this difference by the amount of time the SV
model requires to gather 5 scans to get the maximum speed. Example: a bar code with total width of 3
inches is to be analyzed in a beam length of 6 inches and the SV model being used performs a minimum of
100 scans/analyses per second. Maximum speed of travel is (6 –3)inches /.050 seconds = 60 inches per
second in ladder direction.
Setting Ladder Mode Scanning Length Using ScanVision Software
The distance and location in the laser beam where a bar code is scanned sometimes must be tuned
(programmed) for a particular ladder mode application. In general, the wider the length, the faster the bar
codes can travel. In some cases, a narrower scan length is required to mask an adjacent code so only one
code at a time is scanned. Instructions for using ScanVision software to program the scanning length is
provided in the Setup Procedure Section.
Calibration
Calibration is required if any reflectance calculation (symbol contrast, Rmin, PCS, etc.) is used in the
application. It is recommended to calibrate the unit in any case during initial setup to ensure the scanning
distance and orientation is within device limits. A calibration symbol is supplied with each SV unit as a
standard component. Store it in a clean location.
The SV 2 Series can be calibrated using either of the two following procedures:
Procedure 1:
1.
Remove all bar codes from the laser beam path.
2.
Place the supplied calibration symbol in the laser beam in the same position (distance and
angle) as the labels to be verified will be scanned.
3.
Press and hold the RESET button on the SV unit until the Calibration LED begins to
flash.
4.
Release the RESET button immediately after the Calibration LED begins flashing.
5.
If calibration is successful, the laser beam will go off and the Calibration LED will go
off.
Remove the calibration symbol from the beam path
and
Press the RESET button
until the beam turns on. The SV unit is now ready to operate.
6.
If calibration is unsuccessful, the Calibration LED will be either on steadily or flashing.
In this case, repeat the calibration procedure.
Procedure 2:
1.
Place the supplied calibration symbol in the laser beam in the same position (distance and
angle) as the labels to be verified will be scanned.
2.
Send “~SC” into the SV unit serial port. This will cause the Calibration LED to flash.
3.
If calibration is successful, the laser beam will go off and the Calibration LED will go
off.
Remove the calibration symbol from the beam path
and
then
Press the RESET
button until the beam turns on. The SV unit is now ready to operate.
4.
If calibration is unsuccessful, the Calibration LED will be either on steadily or flashing.
In this case, repeat the calibration procedure.
