If you have difficulties seeing consistent detail in the barcode, so will the optics in the ClassNet/ZipNet Terminal. All bars and white spaces must be clearly printed with sharp edges, and without dropouts. By dropouts, we mean that bars or spaces that are not of consistent and correct width.
Remember that a slot reader such as that on the Terminal reads a tiny slice of the barcode (about 0.1mm wide). In the illustration, dropouts along the scan line have had the effect of narrowing one bar, and splitting another. Additional dirt or ink has also widened a bar. If there are problems with the barcode, you can be sure that Murphy’s Law will place these right in that slice.
There is a “hidden button” on the front panel of the ZipNet and ClassNet Terminals. This button is located vertically down from the I in the name ZipNet (or the L in the name ClassNet) on the front panel label, and horizontally in line with the centre of the IDTag reading assembly.
When you press and hold this button, several items of information are shown in turn on the unit’s display.
Depending on the firmware version loaded in your terminal, the last three items may not be displayed.
There are arguments for either orientation. The horizontal slot is often used as a simple indicator of direction. For instance if a ZipNet Terminal was located on the right side of the entrance to a business, employees coming in to work might scan right to left to indicate they are clocking in, and vice versa when they leave at the end of the day. Some take the view that vertical swiping is easier. The choice is yours, but must be made when you order.
Regardless of orientation, the card must be passed at an even moderate speed along the full extent of the slot.
Instruct users to keep their card parallel to the bottom of the slot as they pass it through.
Avoid rocking the card to ensure an optimal slice of the barcode is presented to the optics (this becomes more critical the higher resolution of the barcode).
Make sure your card has rounded corners so that the card will not catch in the slot. The Terminal slot starts and ends with an ABS plastic “ramp” into a stainless steel bottom. The plastic is intended to be partly sacrificial to adjust to the exact height of the stainless steel section. If you experience any catching of the card as it passes along the slot this will make barcode reading difficult. Check and correct the cause. Perhaps the Terminal case has been incorrectly installed, or the plastic ramps requires wear or slight filing.
When reading a barcode, it is critical that all bars are scanned. A slot reading mechanism such as that used on the ClassNet and ZipNet is simple to use and ensures the correct alignment of the barcode to the reading optics. Provided the card is correctly passed completely along the slot, all bars are scanned. The weakness is that each pass along the slot is discrete, as opposed to a handheld CCD or laser “auto” scanner which scans many times a second while held over the barcode. The auto scanner will also tend to “wander” over the barcode, so that if it is partially defective a successful read is still likely. The slot reader, however, always tries to read the same “slice” of the barcode.
Barcode standards require a “Quiet Zone” of around 6.5mm at each end of a barcode symbol. This Zone must be blank and the same colour (generally white) as the spaces in the barcode. This Zone is required so that the barcode decoder can tell where the barcode symbol starts and stops.
An undersized quiet zone may render a barcode unreadable, or readable only in one direction.
The ClassNet Terminal decodes both Code 39 and Code 128, up to 30 characters long. The ZipNet Terminal, as standard, decodes Code 39 only, but Code 128 is available as an option.
Code 128 has the benefit of generally producing more compact barcodes.
Within reason, barcode symbols should be the lowest resolution (widest bars) possible for your application. This will minimise problems such as dirt on the card being interpreted as a bar, and the effect of drop outs.
If you must use higher resolution barcodes, allow at least 3.25mm per character in a Code 39 barcode, remembering that there are 2 unseen characters, the start and stop codes. (eg. a code containing 14 visible characters, plus the unseen start and stop codes, should be at least 3.25 x 16 = 52mm long).
Even with this general rule, it is important to carefully check the quality of cards, particularly those with higher resolution barcodes, by sample.
As the optic reads a spot about 0.1mm in diameter, and is located 10mm from the bottom edge of the slot, ensure the lines in the barcode are centred 10mm from the card edge to allow for “rocking” or other variations as the card is passed along the slot.
You will probably be using either a laminated card, or a printed plastic card. In both cases, the barcode symbol must be correctly located, clearly printed, of suitable resolution, and observe “quiet zone” standards.
If using laminated cards, ensure there is a clear bond between the laminating pouch and the barcode. Avoid moisture bubbles – any problems usually result from moisture or low laminating temperatures.
If using plastic printed cards, make sure the supplier uses a black ribbon only in the printed barcode (some colour printers use multiple passes of coloured ribbons, producing a fuzzy edge to the bars). In both cases, a magnifying glass or jeweller’s loupe is a handy tool for checking the quality of barcodes, or you can send a sample to ASP.