Intelligent tags have been around since the Second World War, when ‘identification friend or foe’ (IFF) systems were used to identify aircraft, so allies were not shot down by their own gun crews.
More recently, they have been used for tagging pets and farm animals, and are now moving into areas such as luggage and product distribution.
Radio frequency tags can be inductive or ‘true’ systems. Inductive tags are more flexible than bar codes but may be affected by metal objects and other media, so tend to be attached to plastic pallets.
True RFID tags consist of an aerial mounted on a non-conductive substrate like plastic or paper and can be active battery powered or passive.
An alternative to RFID tags is a 2D laser-marked coding system for use where there is likely to be surface wear. The codes can contain up to 2,000 characters and can be read in detail via a CCD-based vision system and computer.