RFID technology has become a critical component in today’s security systems, offering an efficient way to manage access control. Yet, the sheer variety of RFID formats, frequencies, and standards can make selecting the right solution a confusing task. For system integrators, ensuring that RFID readers, transponders, and access control systems work together without compatibility issues is essential for building secure and reliable environments. The challenge of interoperability highlights the importance of choosing solutions that not only meet security needs but also integrate seamlessly with existing infrastructure. How can integrators navigate this complexity and ensure everything works in harmony?
The role of RFID in Security Systems
At its core, RFID systems rely on wirelessly identifying a transponder (such as an access card or vehicle tag) through an RFID reader. This reader then communicates with an access control system that verifies the credentials and triggers actions like opening a gate or unlocking a door. In the security and parking industries, this process is key for managing the flow of authorized personnel and vehicles.
While the concept is simple, behind the scenes is a complex ecosystem of hardware and software. The challenge lies in ensuring all components are compatible, especially given the diverse RFID frequencies and standards in use. System integrators must carefully evaluate new RFID solutions to ensure seamless integration with existing systems, avoiding potential compatibility issues while maintaining security.
Understanding the key components of RFID Access Control Systems
Let’s have a closer look at how RFID access control systems work. A typical RFID system consists of four essential components:
- A central server (S)
- A door controller (C)
- An RFID reader (R)
- An RFID transponder card or tag (T)
The diagram provides a clear overview of these components and their connections. While each part plays a crucial role, there are technical details in how they communicate with each other. In the next sections, we’ll break down these interactions:
1. Reader-to-controller communication
a. Communication interface: The reader connects to the controller through electrical wiring, forming part of the access control system.
b. Communication protocol: A specific protocol encodes the data sent over the physical connection, enabling the reader and controller to communicate effectively.
2. Reader-to-transponder communication
a. Frequency: The encoded number is sent using radio waves at a specific frequency. The frequency of the reader and tag should be the same so they are able to communicate.
b. Wireless protocol: The number is encoded in a specific way so that it can be sent through the air. This communication protocol makes sure that tag and reader understand each other.
3. Tag programming
a. Programming format: That data programmed on the card or tag needs to be in a format that is understood by the reader and that format should also be known in the access control system so that it can be processed.
b. ID number: Each tag holds a unique ID number used to identify a user, whether it’s a person or a vehicle.
c. Facility-code: Tags typically include a facility code, linking them to a specific installation, country, or application. This is sometimes called a client or facility code.
1. Reader/controller communication
The RFID reader must communicate with the door controller to send information about each tag read. Both the communication interface and communication protocol must be compatible between the reader and controller for smooth operation.
a. Communication interface
The reader is physically connected through wires in a cable with a controller that is part of the access control system. This physical connection is called the interface. The hardware electronics of the interface determine if the interface of the reader can be connected to the interface of the controller. Different types of hardware interfaces can be used for this connection, such as RS232, RS422, RS485, Wiegand, and Ethernet. Each interface has unique requirements for cables, including maximum length and wire count, so it’s essential that both the reader and controller use the same interface.
b. Communication protocol
The communication protocol encodes the information sent along the interface, allowing the reader and controller to understand each other. This is similar to using the same language. The communication protocol defines how the information is transferred. There are numerous different communication protocols, like Wiegand 26-bit, Wiegand 37-bit, CR/LF, DC2/DC4 and OSDP. In the access control industry often OSDP and Wiegand are used.
Wiegand Protocol
The Wiegand protocols work with the Wiegand interface and are widely used in access control systems, though they are unidirectional and unsecured. Variants include Wiegand 26-bit, Wiegand 37-bit, Wiegand 32-bit, and Corporate 1000 (35-bit/48-bit).
“Wiegand” refers to both the interface and protocol, which can be confusing. The Wiegand interface specifies the wiring that connects the reader to the controller, while the Wiegand protocol determines how card data (ID numbers) is sent from the reader to the controller. The Wiegand 26 format describes how the number on the card is formatted (8 bits for the facility code, 16 bits for the card numbers and 2 parity bits).
OSDP Protocol
OSDP (Open Supervised Device Protocol) is a more modern, open-standard communication protocol based on the RS485 interface. It is gaining popularity in the access control industry and has several advantages over Wiegand:
- Increased security: OSDP provides higher security, offering a Secure Channel Protocol essential for securely exchanging credentials.
- Ease of installation: OSDP leads to ease of installation through the use of longer cables. This also ensures that fewer wires are needed, which in turn leads to cost savings and a more efficient use of time and resources.
- Open industry standard: As an open industry standard, OSDP offers more flexibility, enabling security professionals to choose compatible devices from various manufacturers. This gives end users the ability to create custom solutions and easily upgrade by adding more devices.
- Bi-directional communication: OSDP allows two-way communication between the reader and controller, enabling remote configuration and management of readers.
OSDP is managed by the Security Industry Association (SIA) and is becoming widely adopted in the security industry as the standard for connecting readers with access control panels (controllers) via RS485. Further information about OSDP can be found at Nedap Insight about OSDP.
Nedap’s product portfolio fully embraces the OSDP protocol. By implementing OSDP, Nedap ensures that its solutions meet the highest security and interoperability standards, providing flexibility for seamless integration into modern access control systems. This compatibility allows for more secure and manageable installations, benefiting both system integrators and end users.
2. Reader/transponder communication
For an RFID system to function properly, it’s essential that the RFID reader is compatible with the RFID transponder, meaning both must operate on the same frequency and use the same wireless communication protocol.
a. Frequency
RFID systems can operate on different frequencies. The antennas on both the reader and the tag are tuned to one specific frequency to enable basic interoperability. The RFID reader and tag should operate at the same frequency. Common frequencies in access control systems include:
- LF: 120-135 kHz (HID Prox, EM, Nedap NeXS)
- HF: 13.56 MHz (MIFARE Classic, DESfire, HID iCLASS, LEGIC)
- UHF: 860 – 960 MHz (RAIN RFID/EPC Gen2)
- Microwave: 2.45 GHz (Nedap TRANSIT)
It is important to realize that local radio regulations prescribe specific requirements for use of the frequency. UHF for example is not globally harmonized, which means that you will need to look out for readers (and tags) that are complying to radio regulations in your country.
b. Wireless protocol
The wireless communication protocol defines how the data on a card or tag is transmitted to the reader and how it should be interpreted. This protocol establishes rules for communication between devices, encoding information to avoid interference from other radio signalsand using algorithms to ensure the correct tag or card is read, even when multiple tags are within range (anti-collision).
Many RFID systems use proprietary air interfaces, which means that both the tags/cards and readers need to be from the same manufacturer. For instance, Nedap’s TRANSIT reader is specifically designed to work with Nedap TRANSIT tags, ensuring reliable performance. However, proprietary protocols limit interoperability with products from other manufacturers, locking users into the same brand for readers and tags.
In contrast, readers and tags/cards that comply with standardized air interfaces are more likely to be interoperable, provided they operate on the same frequency and adhere to the same version of the standard. For example, ISO14443-A is a well-known standard for contactless smartcards operating at 13.56 MHz, which enables basic interoperability with various brands, including LEGIC, HID iCLASS, and MIFARE cards. Similarly, RAIN RFID (EPC Gen2) is a standard for UHF readers and tags that operate around 900 MHz, supported by ISO/IEC 18000-63 and GS1 EPC UHF Gen2 standards. Many compatible readers and tags can work together under these standards.
Securing RFID tags is crucial for reliable vehicle access control. Nedap’s TRANSIT and UHF RFID tags use advanced features like encryption and unique IDs to prevent unauthorized access and cloning, ensuring that only authorized vehicles are granted entry. Learn more about these secure solutions on TRANSIT RFID Tag Security and UHF RFID Tag Security.
While readers and tags/cards may be interoperable, programming tags correctly remains crucial.
3. Tag programming
Tag programming is a critical but complex process that influences security, uniqueness, and user convenience. The programming format ensures the reader can correctly interpret the tag data, while the ID number is crucial for uniquely identifying each tag. An additional code, such as a customer code or facility code, can also be used to group or categorize tags. Below are further details.
a. Programming format
The data programmed onto a card needs to be in a format that the reader and access control system recognize to process it correctly. A wide variety of programming formats is available.
A few common formats are:
- Wiegand 26 bit with or without facility code
- Wiegand 37 bit with or without facility code
- Magstripe (Clock & Data) with several ‘Decimal’ versions
- Nedap propriety format with customer code
The programming format enables the reader to use the correct communication interface and protocol to send the ID number to the door controller. Custom programming may be required depending on the system’s needs.
b. ID number
Tags usually have a ID number. The ID number should be unique for the installation and is used to identify an individual user (like a person or car). Tags usually include a unique number used to identify an individual user, such as a person or vehicle. Many cards come with a preprogrammed unique number, often called a CSN (Card Serial Number) or UID (Unique Identifier). However, it is generally advised not to rely on these preprogrammed numbers, as they are not always unique
Numbers are programmed at a specific location of the tag or card. UHF cards have several memory sections. MIFARE Classic and HID iCLASS cards have specific sections. MIFARE DESfire cards are organized using a file structure.
To program any card, the following information is needed:
- The ID number (range) and optionally the facility code
- The location on the card (sector, file, application)
- The programming format
- The security key
In cases where combi cards are used both sections of the card can be programmed with the same or different numbers, depending on the system’s requirements. Combi cards are equipped with two integrated technologies, allowing for enhanced versatility in access control systems. For instance, a combi card may combine long-range UHF with contactless smartcards offering flexibility for different reader types within the same card. This dual-technology setup makes combi cards a versatile solution, catering to a wide range of security applications.
c. Facility code
Tags often include a facility code (also called site code, client code, country code or customer code) that links the tag to a specific installation, country, or application. This code helps the access control system identify whether the tag belongs to a particular installation and should be processed or ignored. For example, if an installation’s facility code is “1,” only tags with facility code “1” will be read and processed, while tags with other facility codes will be ignored.
Facility codes essentially group tags under a “facility,” helping to avoid duplicate ID numbers within each group. This provides an extra layer of security.
These words all refer to the same thing: the grouping of cards through a number that identifies that group. It is important to be aware about the existence of these codes, since it can cause problems when building access control installation.
Readers, or the access control systems that they are connected to, often are configured to accept only one facility code (or the technical equivalents). When additional tags are procured for an existing installation chances are that a facility code is used. If the new tags have a facility code that does not match the facility code in the reader or the facility code on the existing cards, the newly procured cards will not work.
Nedap readers and transponders often use a customer code. For example, a Nedap TRANSIT Ultimate reader with customer code GF010 will only read transponders programmed with the same GF010 customer code.
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We hope this insight has clarified the essential concepts behind access control cards, readers, and controllers, and how they work together within an RFID system. While the details can seem complex, understanding this basic model can help you navigate the key terms and components more easily.
If you’d like more information or assistance, don’t hesitate to reach out. Contact us today for a personalized consultation on integrating RFID into your security infrastructure.
