The first part of this paper discusses different classifications of Radio Frequency Identification or RFID with special focus on EPC Class 1 Gen 2 tags. The second part of this paper discusses RFID implementation in the SAP world, SAP AII architecture and advantages of using SAP AII instead of third party middleware.
An RFID system consists of RFID tags, which are attached to products, cases, pallets or assets: RFID reader, antennae, sensors, actuators, annunciators, transmitters, and controllers. The system will additionally require middleware software to filter and smooth RFID data and back-end software to collect and aggregate information. An RFID tag basically consists of an RFID inlay enclosed in a label or other case material, depending on its application. RFID inlays consist of an RFID chip and antennae on a substrate. RFID tags are classified broadly as active, semi-passive and passive. RFID tags can have three memory types: Read only (RO), Write-once read-many (WORM), Read/Write (RW). The amount of read/write memory varies from 64 bits to 2 kilobits.
Data transfer between the RFID tag and RFID reader happens by a process called coupling. Coupling happens either electromagnetically (backscatter) or magnetically (inductive). Inductively coupled systems have a short range and are used in applications such as access control. Backscatter technology is usually used in supply chain inventory tracking and asset management. RFID readers are sometimes referred to as interrogators. Interrogators allow the user to read and write data to compatible tags. The readers have a transmitter, receiver, microprocessor, memory, communication ports and optional input/output channels to control external sensors, actuators and annunciators. The transmitter is used to transmit electromagnetic signals using the reader antennae. Signals are absorbed by the RFID tags in their receiving range and energize integrated circuits to transmit a return response. The receiver in the reader picks up the signal from the tag and decodes it, passing the result to a host. Readers may support serial or network communication channels. The controllers allow an RFID system to interface with sensors, actuators and annunciators. Some newer RFID readers provide built-in controller functionality, a key component to create an automated data collection system. An RFID system uses sensors to detect the presence of a case, pallet, or other item. A presence sensor allows the system to trigger the RFID reader for a read and allows the system to act on a “read” or “no read” command when the item leaves the read zone. Annunciators are external notification devices, which allow the system to notify users of the success or failure of an RFID read. An annunciator may be an alarm or a light stack of yellow, green, and red lights. Annunciators are controlled by an external controller or by input /output relays in the reader. RFID systems can potentially generate large amounts of redundant data, which need to be filtered before being sent to back-end systems. Filtering and smoothing of relevant data is the function of RFID middleware. Middleware software hides device-specific protocols and allows management of multiple RFID devices, sensors and annunciators. Some newer RFID readers provide added functionality to do some local filtering on the reader. Depending on the complexity of the architecture, RFID middleware may be a good idea. RFID middleware software can vary greatly in features, from a simple device controller and filtering software, to something that manages a complex network of RFID readers and sensors.
RFID tags are widely classified as active, semi-passive and passive tags. Active tags use an internal battery to power the tags. Passive tags do not have a battery, but use the radio frequency signal from the reader to energize the tag. Semi-passive tags have a backup battery, but do not use the battery to send a constant signal. The tag is...
References: Mark Roberti , “EPC Reduces Out of Stock at Wal-Mart,” RFID Journal. www.rfidjournal.com
Master Guide RFID – Enabled Supply Chain Execution Powered by SAP Netweaver: Using SAP Auto-ID Infrastructure 2.1, Document version 1.2, March 15, 2005, SAP
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