How Does an RFID Reader Work?
RFID stands for Radio Frequency Identification – a technology that transfers data contactlessly via an electromagnetic field. Industrial RFID readers (1) therefore generate electromagnetic waves (2), which are received by the antenna of the RFID transponder (3) and converted into electrical energy which supplies the chip of the transponder with power. The RFID chip then sends a signal (4) back to the reader, which interprets and processes the information. RFID readers therefore work as both write and read devices.
What Are the Technical Properties of an RFID Transponder?
An RFID transponder (also known as an RFID tag) consists of three main components: The antenna, which receives the radio waves of the RFID reader, the RFID chip, on which the relevant data is stored, and the carrier medium, which protects the antenna and the chip from external influences.
What is the difference between active and passive transponders?
Passive RFID transponders obtain the required energy exclusively from the electromagnetic field that the RFID reader sends out. Active RFID transponders, on the other hand, are powered by their own power supply, for example by a battery installed in the device.Which Frequency Bands Are Available for RFID Systems?
The permitted frequencies for production-related RFID interfaces are fixed worldwide. A distinction is made between systems operating in the low-frequency range (LF) from 125 kHz to 134 kHz, in the high-frequency range (HF) from 13.56 MHz and in the ultra-high-frequency range (UHF) from 865 MHz to 960 MHz. Different frequency ranges are used in industry depending on the application. High-frequency RFID systems provide a medium to high transmission speed and are therefore reserved for short ranges. Ultra-high frequency RFID readers are used for applications with a range of several meters.
What Influences the Range of RFID Readers?
Radio waves spread in a spherical shape. If the transponder moves away from the RFID reader, the signal strength decreases squarely to the distance. As a result, if the distance between the transponder doubles, the perceived amount of energy is reduced to a quarter.
What Is an RSSI Value?
The important parameter for defining the possible working range of an RFID system is the RSSI value. This describes the signal strength of the response from the transponder to the RFID reader.
Which Factors influence the RSSI Value?
- Transponder size: The larger it is, the higher the RSSI value.
- Distance between reader and transponder: The greater the distance, the lower the RSSI value.
- Metal and very high water content in the area around the transponder: These can interfere with the radio waves and thus worsen the RSSI value.
- Systems that also work with electromagnetic waves: For example, inductive sensors and RFID systems can interfere with each other.
Demand-based Definition of the RSSI Value
Using IO-Link, the RFID reader can be used to flexibly define which RSSI values the reader should react at. This defined limit value then specifies the minimum RSSI value that must be reached in order to process the transponder data. This enables individually optimized application for clear assignment, tracking and identification within the production process.The effective range of the RFID readers can be divided into four zones, which provide a more precise definition of the working range of the RFID reader.
Which Functions and Operating Modes are Available?
Alarm Mode
The RFID readers offer the option of configuring and triggering up to two alarms. Both specific RSSI limit values and the minimum presence time of the RFID transponders can be specified as triggers.
Definition of RSSI Limit
The RFID reader’s working range can be defined by setting the RSSI limit. This determines how strong the response signal from the transponder must be so that the reader outputs or changes the transponder data.
Communication via IO-Link
Our RFID readers have an IO-Link interface. This makes adjusting parameters and transferring process data quick and easy.
Comparison of Identification Systems: RFID Readers vs. Barcode Scanners
Both RFID systems and systems with barcode scanners enable identification solutions in process automation. Different functional principles and associated advantages enable a wide variety of applications that meet a wide range of requirements.
Benefits of RFID Readers for Identification Solutions
Fast data acquisition and transponders
Thanks to RFID technology, data volumes can be recorded completely and reliably at high speed.
Resistant to contamination
Data can be read or rewritten even in dirty and dusty environments.Clear assignment
Each RFID chip has a serial number that is unique worldwide. This prevents mix-ups at the product and process level.
Contactless and non-visual identification
No direct visual contact is required to identify the transponder. RFID transponders can thus be placed in the tool carrier or in the product, for example, without being visible.
