RFID technology

Radio frequency identification (RFID) was used for the first time in the 80s in applications for tracing and access control systems. These wireless AIDC systems allow contactless reading and are successful in manufacturing and in harsh environments where bar code labels could not last. Due to its capability to track moving objects, RFID has established itself in various markets, including automated vehicle identification (AVI) systems.

RFID is the abbreviation for "radio frequency identification" and means contactless radio transmission of data. RFID technology offers the possibility of reading and writing data – contactless and without line-of-sight – on RFID tags, transponders, SMART labels.

Nowadays, radio frequency identification technology is used in a growing number of fields and industries. However, the technology has existed for more than 20 years. RFID is considered to be a sensible complement to bar code technology. While it has for a long time been used predominantly in closed applications (immobilizers in private cars, security systems, etc.), a standard that is applicable

worldwide now allows industry-independent use of RFID along the entire value added chain. When integrating RFID systems, communication with higher-level EDP systems (ERP, production planning, merchandise management or warehouse management systems) plays an important role.

RFID systems consist of a transponder and a writer/reader. The transponder is the data storage.

Figure 3-6: Basic configuration of an RFID system

Radio waves are the transmission medium for an RFID system. Since data exchange is bidirectional, transponder and write/read device are set up symmetrically to one another. Both components feature a chip for processing the radio signals and an antenna. The transponders usually have no separate power supply and are supplied via the field generated by the write/read device.

Data and power transmission can be inductive, capacitive or electromagnetic. Among other things, the transmission mode depends on the carrier frequency that also determines the system range. While capacitor plates (e.g., for chip cards) are used as antennas for capacitive transmission mode and coils for inductive transmission, dipoles are used in the UHF range.

Small micro-chips are integrated in write/read devices and transponders that encode/decode the data to be exchanged and modulate or demodulate it to the carrier frequency for wireless transmission. Multitag operation is based on different multiplex methods. The write/read device has an interface connection via which it can be connected to a computer, a PLC or a network.

Comparison of DMC and RFID

Whether Data Matrix codes (DMC) or radio frequency identification (RFID):

The high data security of both marking or identification systems is convincing, they have proven themselves in multiple applications even in harsh industrial environments and meet the increasing requirement for full traceability of products and processes. At the same time, they save time and work compared with manual marking and detection technologies.

Main criteria for selecting DMC or RFID:

Can the data medium be reused or is it lost at the end of the machining

sequence?

Single or repeated marking/writing properties within the machining sequence ?

Detection distance

Lighting conditions

Sources of interference (ambient temperatures, dirt, etc.)

Table 3-1: Comparison of DMC and RFID