Overview
Most modern access control systems now use RFID cards or key fobs as the ‘credentials’ held by users to enable them to gain access to restricted areas. The main advantages of RFID over magnetic stripe cards and barcodes are:
- Offer higher level of security, as they can’t be easily copied
- Not prone to wear as they don’t require contact with the reader
- Readers are robust and maintenance free
The RFID transponder comprises a tiny microchip together with an antenna housed in a convenient package. The most common forms of RFID transponder package used in access control is the plastic ISO card (credit card sized) and key fobs (moulded plastic or resin housing that fits on a key ring). Key fobs generally need to be placed a little closer to the reader than cards.
The RFID concept, originally developed for identifying allied aircraft during World War 2, was first adapted for commercial applications in the 1960’s and 1970’s. Since then many technology standards have evolved to meet the requirements of specific RFID applications, which include product tagging, animal tagging and prepayment cards as well as access control.
Virtually all of the RFID standards and variants lend themselves to use in access control. This presents access control system specifiers with a problem of choosing the most appropriate technology for their application.
Because there is very little compatibility between the various card systems, it is important to ensure that the card reader supports both the card technology and the communications interface with the access controller. There are three standard reader/controller interface formats:
- ISO/ABA Track 2 (Clock & Data) – inherited from magnetic stripe readers
- Wiegand – inherited from Wiegand technology magnetic cards
- Serial – compatible with standard RS232 serial interfaces
Nortech readers support all of these standard interface formats.
Some access control companies use a proprietary interface format, which locks customers into continuing to buy their equipment.
The proximity card technologies fall into two distinct groups:
Low frequency (125kHz) – generally referred to as proximity cards
High frequency (13.56MHz) – generally referred to as (contactless) smart cards
Although there are international standards for RFID systems, most systems on the market include some degree of customisation, making compatibility an important point to consider. Fortunately, Nortech’s reader family can read a wide range of technologies and variants.
If you’re looking for an access control system for a new project, then you will need to understand which technology is best suited to both your security level need and your budget. Simply put, Smart Card (13.56 MHz) readers and credentials offer more security and are generally more expensive than proximity (125 kHz) readers and cards. To understand the key differences between the various options available, read the following two sections: