The Magic Behind the Magnetic Card Reader Writer

by

Ewan Fisher

A magnetic card reader writer is a combination device, capable of both data input and data reading. It reads its data from a medium shaped like a card, normally with its information coded on a magnetic stripe (there are other forms of card reader, for example the chip reader).

Technically the magnetic card reader writer is a piece of computational history it bears a strong genetic link to the old punch card readers and writers that were the life blood of the first mainstream computers.

The reader writer reads the information on the strip of the card and sends that data in a packet to its controlling computer. If the computer recognises the information contained in the data packet as valid then a positive state is entered and the computer accepts; if the information contained in that packet comes up against preset rules for exclusion then a negative state is achieved.

The magnetic card reader writer is most commonly associated with access control (these days we tend to use more complex mechanisms for dealing with money, for example). The coding for access control can be as simple as a yes packet or a no packet or even only a yes packet, with the no state being an empty or wiped card.

Modern magnetic card reader writer devices can be set up for simple user control commonly used in hotel access systems and for parking barriers. The card to be validated is programmed in a reader for a certain number of days. At the end of its valid time period (this may be specified to end at a particular time of day, so check out times may be observed) the card will stop working. Access cards can also be programmed with data packets preventing rapid re-use ensuring that parking systems, for example, are not abused by entrants giving a single paid card to several people in a row. Should a magnetic card reader writer programmed card be used in this way, it will deny exit by recording to in states with no out in between.

The advantage of a magnetic card reader writer system is its reliance on a physical object rather than memory. PIN access or the granting of services to a PIN entry are more secure, for the same reason but for basic access to non restricted or sensitive areas it is much easier, administratively and financially to rely on a simple system that can be used by everybody.

Magnetic card reader writer technology is also used in modern clocking in machines. A card programmed with an employee identifier logs in and out events: the reader writer then relays this information to a central control panel, which is used to compile pay data and monitor the punctuality of the employee in question.

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