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Barcode Scanner Reads Nothing: HID, COM and Keyboard Layout

A scanner that reads nothing is four faults sharing one description, and only one of them is hardware. The Notepad test splits them in a minute; the rest is HID reports, keyboard layouts, character timing and the three faults that COM mode swaps in.

Receipt Printer Not Printing: Four Checks Before You Call Support

A dead receipt printer is seven different faults wearing the same description. The self-test page splits them in half in twenty seconds; the other three checks cover paper, data link and the machine, with the numbers that tell you which one you have.

Direct Thermal vs Thermal Transfer: Choosing by Label Life, Not Price

The choice between direct thermal and thermal transfer is set by how long the label must survive and what it must survive. Here is where each one fails, and the arithmetic on ribbon yield.

Label Paper and Die-Cut Sizes: Why the Gap Decides the Printer

A label roll is specified by width, gap, liner, core and caliper. The gap is the one the printer actually reads, and it is the one most purchase orders leave out.

Thermal Paper Rolls: What GSM and Caliper Actually Change

Two rolls labelled 80 x 80 can differ by 12% in length. Caliper, core diameter and roll OD decide the metres; GSM only hints at them. Here is the arithmetic, and what the printer does with the difference.

Android Barcode Scanner: What the USB Interface Decides

Almost every scanner datasheet sold into retail carries a line like System Supported: Linux, Android, Windows, MAC. It sits near the bottom, it is one line, and it is true in the narrowest possible sense: the operating system will not refuse the device. It says nothing about whether the code reaches your application. On Windows […]