RFID

A small tag on a carton, a pallet or an item carries a tiny chip and an antenna. A reader sends out a radio signal, the tag answers with its code, and the reader picks up the answer without seeing the tag, often from several metres away and from many tags at once. Counting or checking goods no longer needs a clear view of each barcode; this technology is called radio-frequency identification (RFID).

It differs from a barcode in three ways: it needs no line of sight, it can read many tags at once, and a tag can be read through packaging. Tags come for different jobs, as labels that stick to a carton, as hard tags for returnable containers and as tags with a battery for long range. The common warehouse type is passive UHF, which has no battery and reads at a few metres.

A tag costs more than a printed barcode, and metal and liquids interfere with reading, so it is worth testing on your own products before committing. The makers below fall into layers: chips, tags and labels, and readers.

When it pays off

It pays off when many items have to be counted or checked quickly: receiving a full pallet of tagged cartons without scanning each one, counting stock in minutes, or confirming that the right items are on a trolley. It pays off best with high-value items, returnable containers and goods such as clothing, where scanning one by one takes too long. It pays off less for low-value bulk items, where the tag costs more than the saving, for products with much metal or liquid, and where barcodes already give good accuracy. Someone has to carry the cost of tagging, and a supplier who tags at source makes the case easier.

What the warehouse system does with it

The WMS does not read tags itself. Readers, at a dock door, on a handheld or at a gate, report which tag codes they saw, and middleware or the reader software turns that into events the WMS can use, such as this pallet has arrived or these items have left. The WMS holds the link between a tag code and an article, batch or pallet, and uses the events to check receipts, update stock and flag what is missing. That link has to be made once, when the tag is applied, and kept right.

Who makes it

Avery Dennison, deister electronic, FEIG ELECTRONIC, Impinj, Nedap, Tageos

In alphabetical order. Not a ranking or a recommendation.