1. Create a new formula
  2. Add the field that will be encoded in the bar code, for example CnBio_ID
  3. Add asterisks around the field: "*" + {CnBio.CnBio_ID} + "*"
  4. Save and Close the formula
  5. Change the font of the formula to "3 to 9 Barcode"
If the bar code does not scan, try changing the font to 24pt.