1. What is RFID?
RFID stands for Radio Frequency Identification. It is an automatic identification technology to identify objects by using invisible radio waves. Instead of optically scanning bar codes on a label, RFID uses radio waves to capture data from tags. One of key characteristics of RFID is that it does not require the tag to be seen to read its stored data. This means that a tag can be placed either inside or outside. To accomplish this, two components are essential, reader and tag. A transponder has a microchip that contains information uniquely identified itself, such as a serial number. A reader sends out a radio signal that wakes a tag from its dormant state. The transponder then responds with a coded radio signal to uniquely identify itself. The reader converts the radio waves returned from the tag into a form that can be passed on to computer that can further utilize the information.
2. What are the major components of RFID system?
a. ) RFID Transponder
A RFID Transponder, contains three kinds of transponder, Proximity smart card (contactless smart card), RFID Tag and Smart Label, is made up of a microchip with a coiled antenna and is used to identify objects, which can be uniquely programmed with information about the objects. RFID transponders can be encased in hardened plastic coatings making them extremely durable and able to be tracked through harsh production processes. They can be read through grease, dirt, and paint. RFID transponders can store large amounts of data. High-end RFID transponders can contain up to one megabyte of memory (one million characters), although most tags only contain a small fraction of this memory, perhaps as little as 64 bits.
Data within a tag may provide any level of identification for an item during manufacture, in-transit, in-storage, or in-use. With additional data, the tag may support applications that need item-specific information. For example, shipment consignee or destination ports can be readily accessed upon reading the tag.
Some RFID transponders are able to support read/write operations, enabling real-time information updates as a tagged item moves through the supply chain.
b. ) Readers (handheld or stationary)
A reader, also called interrogator, is comprised of a transmitter, receiver, control module and a transceiver. The transceiver acts as a communication function to link to a controlling computer or PLC. A reader should have an attached antenna, which is used to transmit and receive the RF signal. Each reader is accompanied with software that allows the user to read and program tags. Serial (RS232 or RS422/485) or Ethernet are the typical communications methods, though others are available.
c. ) A data handling and processing system.
3. How does RFID work?
Information is sent to and read from RFID transponders by a reader using radio waves. In passive systems, which are the most common, The reader sends out electromagnetic waves that form a magnetic field when they “couple” with the antenna on the RFID transponder. A passive RFID transponder draws power from this magnetic field and uses it to power the microchip』s circuits. The chip then modulates the waves that the tag sends back to the reader and the reader converts the new waves into digital data. Then the digital data can be sent to a controlling computer for processing and management.
In active systems, a battery in the tag is used to boost the effective operating range of the tag and to offer additional features over passive tags, such as temperature sensing. Data collected from tags is then passed through familiar communication interfaces (cable or wireless) to host computer systems in the same manner that data scanned from bar code labels is captured and passed to computer systems for interpretation, storage, and action.
4. What are the advantages of RFID?
RFID creates an automatic way to collect information about a product, place, time or transaction quickly, easily and without human error. It provides a non-contact data link, without need for line of sight, for example articles inside a cardboard box, or concerns about harsh or dirty environments that restrict other auto ID technologies such as bar codes. In addition, RFID is more than just an ID code, it can be used as a data carrier, with information being written and updated to the tag on the fly. Genesis has the programming ability to install RFID readers and tags into your material handling system and integrate them with your PC or PLC network. Implementation of RFID will allow the improvement of data quality, items management, asset visibility, and maintenance of materiel. Further, the use of RFID in the supply chain has the potential to provide real benefits in inventory management, asset visibility, and interoperability in an end-to-end integrated environment. RFID encapsulates the data accuracy advantages inherent in all types of automatic identification technology. Additionally, RFID is a totally non-intrusive methodology for data capture (requires no human intervention), is non-line of sight technology, and is a technology that may possess both read and write options within the same equipment item.
5. What is the difference between a passive, semi-passive and active RFID?
Active RFID Tag uses an internal power source, such as a battery, within the tag to continuously power the tag and its RF communication circuitry. Active RFID tag allows extremely low-level RF signals to be received by the tag (since the reader/interrogator does not power the tag), and the tag can generate high-level signals back to the reader/interrogator. Active RFID transponders are continuously powered, whether in the reader/interrogator field or not, and are normally used when a longer tag read distance is desired.
Passive RFID Tag relies on RF energy transferred from the reader/interrogator to the tag to power the tag. Passive RFID transponders reflect energy from the reader/interrogator or receive and temporarily store a small amount of energy from the reader/interrogator signal in order to generate the tag response. Passive RFID tag requires strong RF signals from the reader/interrogator, and the RF signal strength returned from the tag is constrained to very low levels by the limited energy. Passive RFID transponders are best used when the tag and interrogator will be close to one another.
Semi-passive RFID Tag uses an internal power source to monitor environmental conditions, but requires RF energy transferred from the reader/interrogator similar to passive tags to power a tag response. Semi-passive RFID transponders use a process to generate a tag response similar to that of passive tags. Semi-passive tags differ from passive tag in that semi passive tags possess an internal power source (battery) for the tag’s circuitry which allows the tag to complete other functions such as monitoring of environmental conditions (temperature, shock) and which may extend the tag signal range.