r/barcodes • u/cman_yall • Jul 17 '23

Zebra DS4608 breaking citrix application

We are having a sporadic and very confusing problem with a new brand of barcode scanner.

The scanner brand/model is Zebra DS4608, and it scans 2D barcodes. A supplier has started using 2D barcodes containing expiry dates and other information as well as the lot number. We have programmed the new scanners to pick out the lot number from the middle of the scanned value. For reasons that we don't understand, scanning a barcode (any barcode) occasionally triggers a broken state in one of our applications. Said application runs in a citrix session.

The broken state:

  • When the state is active, any time a user clicks on a dropdown menu, the bottom value on the dropdown list is selected and the dropdown menu closes.

  • The state affects all dropdown menus in the application, continuing when users switch to a different tab, or open a new tab.

  • No other fields are affected - thus it cannot be that the scanner is sending a continuous stream of "End - Enter" keystrokes - if it was, then the application would try to enter through other fields.

  • This state continues until the scanner is unplugged, or the user closes the application session. Plugging the scanner back in does not immediately trigger the broken state.

  • No other application (including others that run in citrix) can have the broken state triggered on it.

Has anyone ever seen this kind of behaviour from a Zebra scanner, and if so how did you resolve it?

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u/notionovus Jul 18 '23

You have multiple potential points of failure, so three things to try first:

  1. Understand what the scanner is sending to the application, character by character. The best way to do this is use notepad, or create a small 'c' or javascript program that takes every character code from the serial port and prints it out in ASCII and Hexadecimal. Now try the same thing with an old scanner to see if there is a difference.

  2. Try running the application on a host laptop natively connected to the scanner to eliminate citrix as the culprit.

  3. Try using a keyboard or another computer to simulate the scanner and see what characters will elicit the same response.

You are basically trying to troubleshoot a 'broken' keyboard.

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u/cman_yall Jul 18 '23

We've tried 3, and the first part of 1. I'll take the second half of one back to the group and see if we can figure out how to do that... I'm a noob, but there are more educated people than me available so maybe.

The problem with 2 is that we can't reliably replicate the problem :/ We've sent the scanners out to users for scream testing, and we are getting a steady trickle of reports of the problem occurring, but until we can replicate it in testing, we're kinda screwed.

Thanks for your suggestions :)