Marin County Free Library — Technical Services
Barcode Scanners — Troubleshooting

Barcode scanners are used to quickly and accurately read barcodes into computers, in libraries, stores and almost everywhere else in industry. A scanner at its most basic is just an extension of the computer keyboard, and sends a set of numbers and a carriage return to the computer, sometimes on the same "chain" of cables used by the keyboard.

Barcode Wands
The oldest and most basic barcode readers in the library are handheld wands. On a personal computer, these work by being daisy-chained in with the PC's keyboard, using a split cable called a "wedge." There are usually three parts to a wand:

  • The wand itself
  • The decoder box
  • The wedge, or cable

The steps in troubleshooting a typical wand on a PC are:

  1. Check that all of the cables are secure. If the keyboard won't type, then something is loose.
  2. Some decoder boxes have an on/off switch. Make sure that this did not get turned off.
  3. The wand should have a laser light showing at the tip. No light means that something is loose, something is turned off, or the wand itself is dead.

Early Handheld Barcode Scanners
The earliest handheld scanners, and those used frequently at staff workstations throughout the library, are actually simpler than wands. The units, usually Symbol or Metrologic scanners, don't have that extra decoder part, and the cable wedge is built in, so that they're basically one piece scanners. The only troubleshooting for these units is to make sure that they're plugged in. And again, the keyboard on the PC should work, or something is loose.


Modern (ScanEze) Barcode Scanners
Since 1998 we've been using various models of ScanEze barcode scanners on our circulation desks. These read faster, easier and from greater distances than the older handheld scanners, though they are more complex and cost a great deal more.

Since they're more complex, there are more steps to troubleshooting a ScanEze scanner.

No scanner light coming from scan head

  1. Make sure that all connections are tight, scanner is plugged in, and that the decoder box has power and is turned on. (There is a switch on the side of the decoder box.)
  2. If the decoder has power, switch it off and back on again.
  3. If there is still no scanner light, call Tech Support.

Scanner has light, but won't scan barcode into MillCirc or E-Term32

  1. Switch decoder box off and on again.
  2. Check connections, especially on the keyboard wedge and decoder box.
  3. Open Notepad or Word and see if scanning a barcode works.
  4. If none of that works, call Tech Support.

The most common problem with the scanners is that the decoders need to be turned off and back on again. Other than that, the decoder boxes sometimes lose their programming, and the scanner heads sometimes fail internally and need to be repaired. If one of your ScanEze circulation desk scanners won't work, and you have one elsewhere in the library that you can work without for a short period, it is OK to swap scanner heads in order to keep your primary station working.

To remove a scanner head for swapping, pinch the connector at the decoder box, and feed the cable up through the desk. The newest scanner heads have a separate power supply, so it's best to avoid using these to swap in for other units.


Esoteric Details of Barcodes
There are many types, or "symbologies" of barcodes. Most people are familiar with the UPC barcode used in retail sales, but this is not what libraries use. Our barcodes are called "Codabar," which is used only for numbers. We don't see the extra characters, but each of our barcode labels begins with a capital A, and ends with a capital B, with numbers in between the two. The scanner interprets this as just the number, followed by an "Enter" or carriage return.

If you want to play with Codabar barcoes, install the Codabar font onto your PC, and type up some barcodes in word, and see if your scanner will scan them. Remember, capital A, number number number, Capital B.


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Last modified May 12, 2005 dtm