INFO

What is a RFID reader?

A RFID reader is an electronic device which communicates with RFID transponders containing Radio Frequency Identification chips and antennas. These readers have a transceiver that emits an electromagnetic field, and when the RFID transponder comes within its proximity range the transponder emits the electromagnetic signal (ID or other data) and the reader reads it. When encoding, the “reader” changes the content of the transceiver EEPROM memory.   


RFID Reader Operating Frequencies

RFID readers are divided into frequency bands in which they operate. The most popular frequency bands are:

•    Low Frequency Readers operate usually at 125 kHz, sometimes 134.5 kHz, 
•    High Frequency Readers operate usually at 13.56 MHz
•    Ultra-High Frequency Readers operate usually at 860 MHz to 960 MHz.
•    Microwave RFID readers operate usually at 2.45 GHz

Ultra-High Frequency Readers have to use a specific frequency for a specific country or region. Designated UHF frequencies for Europe are 865 to 868 MHz.

Some RFID applications are using their own communication protocols or frequency bands and standard readers are not working with such applications.

RFID Reader Working Modes

RFID readers can work in different modes:

•    Keyboard Emulation Reader - enters the chip ID onto a computer display,
•    Virtual COM Reader - reads the chip ID onto a computer’s virtual COM port, 
•    Serial COM reader - reads the chip ID onto a computer’s COM port, 
•    AutoRead reader - automatically reads the data from memory,
•    PC/SC and CCID device - reader/writer which needs API integration with software solutions
•    Wiegand Reader - uses 3 wire protocol to transmit the chip ID to a controller,
•    Controller with relay – a device that receives the data from the reader, contains a software interface and relay for opening door locks.

Transponders for RFID readers

There are two main types of RFID transponders: Passive and Active RFID transponders.

Passive RFID transponders are common, inexpensive RFID tags which respond only after they receive a reader’s signal. They usually contain a standard RFID chip and an antenna.

The most common passive RFID chips are:
13.56 MHz chips: Mifare Classic®, NTAG, ICODE®, DESFire®, Ultralight, Fudan F08, etc.
125 kHz chips: EM4200, EM4102, EM4100, TK4100, T5577, EM4550, HITAG®, etc. 
UHF chips: Alien Higgs-3, UCODE 8, Monza® R6

The usual reading distance for 13.56 MHz and 125 kHz chips is 1–5 cm and up to 7 meters for UHF. 

Passive RFID transponders are available in various forms:

-    RFID COB’ (Chip On Board), where there is only a small rectangular tie containing the RFID chip and the copper winding.
-    RFID Dry Inlay, where the chip and antenna are on thin clear plastic material
-    RFID Wet Inlay, where the plastic material with the transponder has an adhesive
-    RFID sticker/label, where the transponder has a plastic or paper layer on top which can be printed and adhesive on the bottom side
-    RFID tag, where the transponder is inside die-cut plastic
-    RFID card, where the die-cut plastic with a transponder is standard credit card dimension
-    RFID Key Fob, where a transponder is inside a key fob housing
-    RFID Bracelet or wristband, where a transponder is inside a wristband


Active RFID transponders has its own power source – an internal battery that enables them to have extremely long read ranges (up to 150 meters), as well as large memory banks. They usually operate at frequency 2.45 MHz and at 433 MHz. The 433 MHz transponders workg even with some non-RF friendly materials like metal and water. Some active transponders reply when they receive the signal from a reader, other active transponders work as beacons and emit the signal in a specific period of time (3–5 seconds). The Active RFID transponders are more expensive (25 –100 €) and they are usually used for tracking high worth assets or for items where accurate location tracking is necessary. A few examples of these type of assets are cargo containers, machinery, etc.

RFID Reader Standards

When choosing the reader and transponders, you have to be aware of several standards. The transponder working on the same frequency as the reader is not enough to guarantee that they will work together. Even certain NFC readers are not suitable for all NFC transponders.
The most popular standards that define the RFID transponders and communication protocols with readers are: 

ISO/IEC 14443 is standard which defines the communication between 13.56 MHz readers and transponders (used in chips MIFARE®, NTAG, DESFire® and chips from other manufacturers). Transporders may be Type A and Type B. The main differences between these types concern modulation methods, coding schemes (Part 2) and protocol initialization procedures. Both Type A and Type B cards use the same transmission protocol.

ISO/IEC 15693 is another standard used usually for ICODE® chips and others, for library applications, asset identification, etc. The standard is used for 13.56 MHz chips and UHF as well.

ISO/IEC 18000 defines the air interface communications for various frequency bands (ISO/IEC 18000-2 for frequencies below 135 kHz, ISO/IEC 18000-3 for 13.56 MHz, ISO/IEC 18000-6 for UHF frequencies).

ISO/IEC 18092 is NFC standard which contains a set of communication protocols for Near-Field Communication (NFC) which operates at the distances up to 4 cm.

ISO/IEC 21481 is another NFC standard which contains a set of communication protocols for Near-Field Communication (NFC) which operates at the distances bigger than 4 cm.

ISO 11784/11785 is a standard for 134.2 kHz readers and transponders used for animal identification. 

ISO 14223 defines advanced transponders for identification of animals (example HITAG® µ HITAG® Advanced / Advanced+).

ISO 18185 is the industry standard for electronic seals or ‘e-seals’ for tracking cargo containers using the 433 MHz and 2.4 GHz frequencies.

ISO 28560-2 specifies the encoding standards and data model to be used within libraries.

Communication Protocols

When selecting the suitable equipment for your RFID solution you shoul thing about the communication protocols and their limitations. 

RS-232 is a standard for serial communication between electronic devices. It defines the electrical characteristics and timing of signals. The maximum cable length can be 15 meters. This protocol is usually used to connect serial readers to the peripheral devices with serial COM ports (older PC, industry or other specialised equipment, controllers).

RS485 is also a standard for serial communication where the its generally accepted that it can be used with data rates up to 10 Mbit/s. A rule of thumb is that a 50-meter cable should not signal faster than 2 Mbit/s, but at lower speeds the cable could be as long as 1,200 m. This protocol is usually used to connect wall-mounted readers to controllers.

USB (Universal Serial Bus) is an industry standard that establishes specifications for cables, connectors, and protocols for connection, communication and power supply computers and peripherals. A broad variety of USB hardware exists, including eleven different connectors, of which USB-C is the most recent. The maximum USB cable length 3 – 5 meters, but there are at least two options to increase the cable length. You may use an Active USB cable with additional electronics which amplifies a signal or USB over Cat5/Cat6 Extender which transmits a USB signal over Ethernet and converts it back to USB on the far end. The USB protocol is used to connect desktop readers to PC, laptops, tablets, and mobile phones. 

The Wiegand protocol is communications protocol used on a Wiegand interface. It uses three wires, one of which is a common ground and two of which are data transmission wires usually called DATA0 and DATA1, alternately labeled ‘D0’ and ‘D1.’ The cable distance recommendations for Wiegand protocol vary from reader to reader. The Wiegand protocol is used for communication between wall-mounted readers and nearby controllers.

The Ethernet is a family of wired computer networking technologies commonly used in local area networks (LAN). Category 6 cable (Cat 6), is a standardised twisted pair cable for Ethernet. The standard version of Cat6 has a maximum distance of 55 meters, but there are other cable versions which reach distances up to 100 meters. RFID readers with ethernet connection are not so common and are usually more expensive.

TCP/IP is a set of communications protocols used in the Internet and similar computer networks. ‘TCP’ stands for Transmission Control Protocol and ‘IP’ stands for Internet Protocol (IP).

Serial TTL (Transistor-Transistor Logic) is similar communication protocol to RS-232, but a TTL level will always remain between the limits of 0V and 5V, where 5V or 3.3V.  is often a logic high ('1'), while 0V is a logic low ('0'). This protocol is used with low-end equipment like card dispensers or collectors.  

Bluetooth is a short-range wireless technology standard used for exchanging data between fixed and mobile devices over short distances. A use example is a handheld RFID reader which communicates with a nearby laptop or PC. The most common distances for Bluetooth are 5–10 meters.   

Profinet, Profibus, IO-Link are industrial communications networking standards used with specialised RFID readers for industry applications. These high reliability devices are made for harsh environment and contain special electronics. Usually they are more expensive than other kind of readers.

PC/SC (Personal Computer/Smart Card) is a specification for smart-card integration into computing environments.

CCID (Chip Card Interface Device) is a USB protocol that allows a smartcard to be connected to a computer via a card reader using a standard USB interface, without the need for each manufacturer of smartcards to provide its own reader or protocol.

CT-API (Card Terminal Application Programing Interface) is a specification for smart-card integration into computing environments. 

RFID Reader Applications

Some common uses for RFID readers and transponders include:

•    access management (electronic keys for RFID based lock system)
•    pet and livestock tracking
•    person and vehicle tracking
•    inventory management and control
•    goods, asset, and equipment tracking
•    toll collection and contactless payment
•    machine readable travel documents
•    Smartdust (for massively distributed sensor networks)
•    timing sporting events
•    tracking and billing processes.


RFID Readers on Metallic surfaces

If you place a RFID reader on a metallic surface, the magnetic fluxes of the reader will induce eddy currents within the conductor and they will cause poor performance or the reader not to work at all.

To ensure that the reader will perform well, we recommend that you mount it on plastic, wood, or other non-conductive material with the thickness at least 1 cm or more. 

To protect the reader performance near to metal there are also available special protective materials like 3M™ Flux Field Directional Material (FFDM) EM15TF. These materials have a thickness of 0.05 mm – 0.5 mm and are usually used in mobile phones with NFC reader where the antenna is very close to battery or electronics and electronic other devices.

Do you need some help choosing the right RFID reader?

As you can see, the field of RFID readers is very extensive and complex and
if you need help choosing the right device, please describe your application and we will help you. For more complex projects, we offer consulting services as well.

Send an email to info@rfidspecialist.eu or call +38641 884 124 and we will be happy to help you.