Opticon XPT 3125 Universal menubook - Manual (Page 49)

OPTICON Universal menu book
U42
3.2. Setting of number of characters
If you are going to read bar codes of known
length, it is recommended to set the reader for
a fixed number of characters. This can be done
for up to two lengths. The reader uses this to
verify that labels read are of the correct length,
rejecting any labels which do not have the
specified length. The advantage of setting a
fixed length, is that it provides protection
against short scans of labels, such as
Interleaved 2of5, which do not provide sufficient
security against partial scan. The length
checking is done on the label data and is not
affected by options such as (not) transmit start/
stop character or check digit. Setting the
number of characters does not affect fixed
length codes, such as EAN-13. 2D
symbologies such as PDF417 and Data Matrix
are also not affected by fixed length settings.
The following options are available:
Fixed length OFF all codes.
This option cancels the fixed length checking.
Fixed length ON all codes.
This option enables the fixed length checking.
Two fixed lengths are programmed which will
affect all variable length codes. This is done by
reading the following labels:
a bar code with the required length,
a second bar code with the required length
(this may be the same length as the first one)
See figure 3.06.
Enable all 1D codes BCM
_BCM_
Enable all 2D codes BCN
_BCN_
Disable all B0
_B0_
SET
_ZZ_
END
_ZZ_
Fig. 3.06. Setting Fixed length ON
all codes
SET
Fixed length ON
Scan a bar code
with the required length
Scan a 2nd bar code
with the required length
END