In today’s globalised business environment, RFID (Radio Frequency Identification) technology has become the cornerstone of supply chain management, asset tracking, and retail operations. To help users better understand the technical core of RFID tags, this article will delve into the four primary storage areas of UHF RFID tags: RFID Tag EPC (Electronic Product Code), TID (Tag Identification Number), User Memory, and Reserved Memory.
Overview of RFID Tag Storage Structures
The internal storage space of UHF RFID tags (adhering to the EPC Gen2 protocol) is not disorganised but meticulously divided into four distinct banks. Each bank serves a specific function, ensuring efficient and secure data read operations. Understanding the distinctions between these areas is crucial for selecting the appropriate RFID product.
| Storage Area Name | Bank ID | Primary Function | Read/Write Attributes |
| Reserved Area | Bank 00 | Stores deactivation password and access password | Read/Write (Restricted) |
| EPC Area (EPC) | Bank 01 | Stores the electronic product code of the item | Read/Write |
| TID Area (TID) | Bank 10 | Stores the unique hardware identifier of the chip | Read-Only (Factory-Fixed) |
| User Area (User) | Bank 11 | Stores additional custom business data | Read/Write (Optional) |
EPC Storage Area: The “Digital ID” of an Item
The EPC (Electronic Product Code) storage area is the most frequently used section within an RFID tag. It is designed to store a globally unique code for identifying specific individual items.
Data Composition of the EPC Area
The EPC storage area contains not only the EPC code itself but also two critical auxiliary data segments:
- CRC-16: Used for data verification to ensure data integrity during the reading process.
- PC (Protocol Control): Defines the length of the EPC code and other protocol attributes of the tag.
Why is EPC writable?
Unlike traditional barcodes, EPC can be rewritten multiple times. This allows distributors or retailers to redefine tags according to their own coding systems. For example, after receiving original tags from factories, Uniqlo can update the internal EPC code to specific SKUs and serial numbers.
Pro Tip: While EPC is rewritable, for security purposes, the EPC zone is typically set to “locked” status before final delivery to consumers to prevent unauthorised tampering.
TID Storage Area: The Chip’s “DNA”
If the EPC is an item’s “license plate,” then the TID (Tag Identifier) is its “VIN.” The TID is permanently burned into the silicon wafer during production by chip manufacturers like NXP, Impinj, or Alien.
Uniqueness and Immutability of the TID
The TID area is typically read-only. It contains the manufacturer’s code, the chip model, and an absolutely unique serial number. This characteristic makes TID the optimal tool for anti-counterfeiting and traceability. For brands like Nike or Adidas, utilising TID effectively prevents counterfeit products from entering the market, as forgers cannot replicate the unique TID sequence permanently embedded within the chip.
Comparative Analysis of EPC and TID
To clearly illustrate their differences, refer to the table below:
| Characteristics | EPC Storage Area | TID Storage Area |
| Definition | Electronic Product Code | Tag Identification Number |
| Source of Uniqueness | Assigned by user or software | Factory-set by chip manufacturer |
| Modifiability | Yes (rewritable multiple times) | No (permanently read-only) |
| Primary Uses | Inventory management, asset tracking | Hardware anti-counterfeiting, chip identification |
| Length | Typically 96-496 bits | Typically 64-96 bits |
| Analogy | Human name (changeable) | Human fingerprint (unchangeable) |
User Memory: The “Memo Pad” for Expanding Your Business
Not all RFID tags feature a User Memory area. However, it is indispensable in complex industrial applications or high-value asset management.
Typical Uses of the User Area
- Production Records: In apparel manufacturing, the user area can log dye batches, fabric compositions, or quality inspector IDs.
- Maintenance Logs: For RFID tags installed on expensive equipment, the user memory can store the date and personnel of the most recent maintenance.
- Encrypted Information: Stores sensitive local data that does not require real-time queries to a back-end database.
User Memory Capacity Selection
User memory capacity varies significantly. Basic chips may lack user memory, while advanced chips (such as the UCODE series) can offer up to 512 bits or more.
Reserved Memory: The Secure “Gatekeeper”
Reserved Memory is the most concealed section of the tag, primarily storing two 32-bit passwords:
Kill Password: Once a deactivation command is executed and matches this password, the tag becomes permanently invalid. This protects consumer privacy in retail by ensuring tags cannot be read after the merchandise is sold.
Access Password: Used to lock or unlock the EPC area and user area. Only readers possessing the correct access password can modify tag content.
How to choose a storage solution based on business requirements?
When communicating with clients, the question often arises: “How much memory should I choose for my tags?” The answer depends on your application scenario.
Scenario 1: Apparel Retail (Uniqlo, Zara, etc.)
These brands typically require only the standard 96-bit EPC. With robust back-end databases storing all product details (colour, size, price) in the cloud, the tag serves merely as an “index key.” Consequently, expensive user memory isn’t needed, reducing per-tag costs.
Scenario 2: Luxury Hotel Key Cards
For renowned hotel brands, security is paramount. We recommend chips with robust encryption capabilities and larger user areas to store encrypted room numbers and validity periods.
Scenario 3: Logistics Distributors
Distributors often handle goods from multiple suppliers. Tags with rewritable EPC zones enable them to integrate shipment data into their ERP systems without replacing tags.
Conclusion
Understanding the storage zone structure of RFID tags—EPC, TID, user area, and reserved area—is the first step toward achieving efficient automated management. The EPC provides flexible item identification, the TID ensures hardware authenticity, the user area expands local data storage, and the reserved area safeguards system security.
If you’re seeking a reliable RFID partner, RFIDLabel stands ready to support you. Whether it’s custom RFID tags or complex RFID solutions, we leverage deep industry expertise and robust manufacturing capabilities to propel your business forward.
