How to troubleshoot barcode ‘’no read’’ on PosID?

This article explains how to troubleshoot when the barcode is not read by PosID.

The PosID (Positive Identification Module) reads barcodes on carriers and containers. (e.g. sample tubes, microplates, etc.) The PosID can read horizontal and vertical barcodes. When PosID is not able to read the barcodes, the issue is either related to the barcode label or to a malfunction of the hardware.

To eliminate the barcode label as an issue please check : 

1. Barcode Label Quality
  • The barcode labels must fulfil the following specifications:
    • Module width: 5 to 15 mils (0.127 to 0.381 mm)
    • Quiet zone (QZ): ≥ 5 mm
    • Barcode height: min. 7 mm
    • Barcode length: Max. 64 mm (without quiet zone)
    • Number of characters: Max. 32
    • Black symbols on white background

Every barcode has graded standard which defines the quality of the barcode labels regarding symbol contrast, reflectance, and edge determination. To avoid misreading barcode, the quality of the barcode labels must be graded A, B or C according to ANSI X3.182 and DIN EN 1635. Tecan recommends using grade A for best reading performance. A quality system in the production of barcode labels must be employed to ensure the conformity to the quality grades mentioned above.

To ensure good reading results, attention should be paid to the following recommendations:

  • Use a barcode testing device to verify the barcode quality.
  • Maintain print quality: Use barcodes printed by means of a thermal-transfer or photographic printer.
  • Barcode label surface must be mat and clean.
  • Do not use yellowed, stained, creased, wet or damaged barcode labels

      2. Barcode Label Positioning

      The figure below shows the dimensions for barcode label positioning on tubes.


       The figure below shows how to position the barcode labels on reagent troughs. 


      The figure below shows the dimensions for barcode label positioning on microplates.


      The figure below shows the dimensions for barcode label positioning on carriers:


      If the barcode label has the right standard of quality and its position is according to the specifications above, please check if the laser output window is dirty and, if so clean it according to the Operational Manual.

      If there is still no improvement, please contact your local Helpdesk for further assistance. 


      Further help

      For further help, please refer to our Helpdesk.


      Link to Tecan Product Page:

      Freedom EVOware®