Tips For Verifying The Presence Of A Bar Code - Omron V520-LHA7127 User Manual

Section 3 - Positioning the Scanner

Tips for Verifying the Presence of a Bar Code

If the scanner is operated in the "trigger enabled" mode and the trigger is activated, one of three conditions
may occur.
A bar code is scanned and decoded
A bar code is scanned but is not decoded
(e.g., print quality was poor)
No bar code is present
In some applications, when no data is transmitted, it may be important to know why. Was there a bar code
present that could not be decoded, or was no bar code present at all?
This requirement is common in applications such as automated blood analysis equipment. Test tubes
containing blood samples from many different people are loaded into a rack for automatic analysis. The bar
code on each tube ties that sample and the results back to a specific individual. If no bar code data is
transmitted it is critical to understand the reason.
Your Omron scanner, when operated in the Trigger Enabled mode, can be programmed to transmit an error
message indicating whether or not a bar code was present. The following table shows the message that will be
transmitted for each condition.
Presence/Absence of bar code
Bar code was present and correctly decoded
No bar code was present
Bar code was present but could not be decoded
14
Decoded data is transmitted
No data is transmitted
No data is transmitted
Scanner Transmits
Decoded Data
<STX> "?" <ETX>
<STX> ">" <ETX>
V520-LHA7127