By Mary Catherine O'Connor
Jan. 31, 2006—At a meeting of the
Auto Industry Action Group (AIAG) last week in Detroit, an ad hoc team of
International Organization for Standardization (
ISO) and
EPCglobal representatives provided a roadmap for realizing a proposal to enable the
EPCglobal UHF Gen 2 air-interface
protocol protocol to accommodate other data formats used by not just the auto industry, but other vertical industries, as well. The group spearheaded the effort to develop the proposal, which it plans to submit to ISO's U.S. Technical Advisory Group (US
TAG) for consideration, once ISO ratifies Gen 2 as
ISO 18000-6c, which is expected to happen soon.
In December, Sue Hutchinson, the EPCglobal US director of product development, made a proposal to the AIAG that its members utilize the "user
memory" portion of the EPC Gen 2/ISO 18000-6c protocol to encode with industry-specific data. Such data would include the
U.S. Department of Transportation (DOT) tire identification number, which provides information on its manufacturing date and location, into a tag (see
Auto Industry RFID Data Standard Proposed). However, the group had not yet figured out how an
RFID interrogator would access that user memory.
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Craig Harmon
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Specifically, the proposed revision is to use a bit (bit 15) within memory bank 01 of the protocol control section of the unique item identifier (UII) of the ISO 18000-6c and EPCglobal UHF Gen 2 air-interface protocol to indicate whether a user (e.g.,
Michelin) has encoded data to the user memory portion of the 18000-6C-compliant tag. Within this user memory, a tire maker would encode industry-specific data, such as the DOT tire ID. If the RFID interrogator reads bit 15 as a 1, indicating user memory is being used, it would then read the data within user memory. If bit 15 is a 0, the interrogator would not attempt to read the user memory section of the code.
This approach, sometimes referred to as a toggle bit, is already used within the Numbering System Identifier (NSI) field of the Gen 2 protocol to identify whether the tag uses an
EPC, such as a serialized Global Trade Item?Number or a Serial Shipping Container Code, or an ISO Application Family Identifier (AFI), such as a part identification number or a unique item number called a
license plate number (see
Gen 2 Finds a Path to ISO Approval).
Using both of these toggle bits (bit 17 within the code's NSI and bit 15 within the UII), a tag encoded with the proposed revision could identify itself as one of four things: as an EPC (bit 17 is 0) with user memory (bit 15 is 1); an EPC (bit 17 is 0) without user memory (bit 15 is 0); an AFI (bit 17 is 1) with user memory (bit 15 is 1); or an AFI (bit 17 is 1) without user memory (bit 15 is 0).
The proposed revision also calls for the user memory to be formatted in compliance with the ISO 15961 and 15962 RFID data protocols, which were designed to provide a means of seeking out specific data from a tag, such as a
unique identifier or an expiration date or lot number. "Say, all I want to
read is the DOT code," explains Craig Harmon, president and CEO of information system consultancy
QED Systems and US TAG SC 31's senior project editor for ISO 18000 air-interface standards. "The 15961/15962 protocol tells the [RFID interrogator] how to get that data."