RFID Technology is the acronym for Radio Frequency IDentification and is a technology for automatic identification of objects, animals and even people. An RFID system consists essentially of three basic elements:
- An antenna
- A Reader
- A transponder, commonly called Tag, can hold data.
The system is based on remote reading of information contained in the RFID Tag using readers. The antenna emits an electromagnetic wave that activates the Tag to read or write information about it. The antenna is connected to the reader that, properly connected to a personal computer with the relevant software, controls and captures the data flow.
Classification of TAGs
The performance of an RFID system is not dependent on the reader, as it is sufficient to dimension the antennas or the control unit appropriately. With regard to RFID tags, you can classify in some general categories, depending on the performance required in terms of reading distance, storage capacity, and so on.
Classification by source of power supply
Passive tags: They are the cheapest type, as they do not have a source of their own power supply, and are powered by the same electromagnetic field of the reader.This means that the Tag can only be used if it is exposed to the reader.
Semi-passive tags: They come with a battery, but it does not power the Tag until it receives a signal from the reader.
Active Tags: They are battery-powered and continuously emit an identification signal that allows for constant localization;
they are usually larger and more expensive than the previous one, due to the built-in battery, and continuous operation allows lower life cycles.
They allow reading distances of tens of meters and are used for vehicle location, electronic payment systems, fast location of open reusable objects (such as pallets),etc.
Generally, with the increase in work frequency, the reading distance, the data transfer rates and the number of simultaneous readings increase, while the production costs and the physical size of the tag decrease.
Unfortunately, however, the higher the frequency the more degradation of reading performance occurs in the presence of liquids that tend to absorb radio waves, and metals, which tend to deviate from them.
By increasing the frequency at UHF, it comes between 300 MHz and 1 GHz with 433 MHz and 865-915 MHz tags.
The advantage of raising the frequency allows for small-size antennas, so suitable for portable devices with distances that also reach 10 meters for passive tags under special conditions.
Even in the absence of a perfect alignment between the Tag and the Reader, good communication levels are obtained.
Read-only and read/write modes
Read-only mode allows you to use RFID technology to replace bar code by leveraging the following benefits:
- Reliability of reading
- Eliminating the need to "see" the label (radio labels can be contained within the product and can be read in multiple copies at the same time)
- Ability to work in contaminated and dirty environments
- Ability to whitstand, with appropriate protection, the aggression of chemical and environmental agents, to be immersed in a fluid, within the object that is to be identified, or within another container (provided that it is not completely metallic)
- Possibility to read the code of tens or hundreds of labels in the same container within a few seconds, and to trasmit it to the information management.
Tags with non-volatile memories (few kilobytes) can contain highly articulated information about the object to which they are associated
The read/write mode allows not only information transmission but an update on the chip. The tag becomes an identification system that can track the history of a product from the processing stage and then be used interactively across the entire chain to retail and in some cases to the consumer.
Some benefits of this mode include the ability to store data on quality indices, problems encountered, and later, by simply reading the tag, evaluating the positive and negative features of products or batches; for example, applied to packagings of perishable products at high temperatures can inform the consumer that the level of protection of these has been exceeded (eg: dead truck stopped for hours under the sun). In particularly complex and hostile industrial systems, the presence of a tag in these modes can replace both the network and the need to always have control of a management system and thereby automate some administrative or industrial processes, locate store different models, distribute models and products according to some features (price, size, packaging, etc.). These tags are also useful for automatically generating bubbles and invoices, with the ability to simultaneously read multiple codes. The sales phase also benefits from using tags, both for real-time inventory and sales, and because tags can be used as anti-theft devices.
Each RFID tag is equipped with a chip that contains 3 different types of memory:
1. EPC memory
This memory contains the EPC code of the tag. EPC means Electronic Product Code has a minimum capacity of 96 rewritable bits. This code is what is used as an identifier in most RFID applications. This is the first memory that the user can modify.
2. TID memory
This memory is used only to store the UID code of the tag itself. This is the unique transponder identification code. This memory can not be written or rewritten by anyone. The code is inserted directly from the manufacturer and no one can modify it.
3. USER memory
This memory is used in all those applications where it is not enough to use the EPC code and then use this memory to enter additional information to store and pair with the tag. Smaller memories are usually 32 bits up to 512 bits. This memory is the second that the user can modify.