RFID Systems - Allied Automation, Inc.

RFID SystemsFundamentals of RFIDTrains – As trains move into stations or pass checkpoints,a high-speed reader relays information back to the trackingstation.Comparison Between FrequenciesAll of these frequency ranges bring advantages. It is importantto select the right frequency for your application.Read/write ranges for low and high frequency inductivesystems (125 kHz-13.56 MHz) range from fractions of an inchto 1 foot. Read only and read/write tags typically operatepassively and reflect or modulate the transmitted signals.These systems are particularly suitable for applications in thearea of automation, material handling, data aquisition or theidentification of objects such as storage containers, pallets,tool holders and similar items.Identification systems with ultra-high frequency (~2.45 GHz)operate according to the principle of Hertz dipole in the farfield, making it possible to reach larger read/write distances.Typical read/write range will be many feet. The code and datacarriers have an energy source of their own to supply theinternal electronic circuitry. Typical applications include theidentification of larger objects in automotive production, or forsimultaneous identification of several units on a conveyor line. 125 kHz/250 kHz 13.56 MHz 2.45 GHzWavelength 2400 m, 1200 m 22 m 0.12 mEmbeddable In Metal Yes No YesMetal In Environment Yes Some YesPenetration ThroughWaterVery good Average NoneReflections None Low HighestElectrical Interference Very High High LowTransfer Speed 2-10 kbit/s 26 kbit/s 76 kbit/sRead Range 150 mm 300 mm 4000 mmWrite Ranges 140 mm 250 mm 4000 mmTypical ApplicationTool ID, partstrackingPallet tracking, binlabelsAutomotive, highspeedPrice Range $3 - $96 $1 - $39 $62 - $290RFID Systems SelectionCycle TimeTypically, the higher the frequency the faster data can betransferred to and from the RFID tag. Other times must betaken into consideration to understand the complete systemcycle time. You must take into consideration the following:• Upper level bus-system scan times of networks likeDeviceNet, PROFIBUS, Ethernet, and RS-232 will changedepending on network loading, baud rate, etc.• PLC scan time: The PLC may only see the rung thatreceives the RFID data every 30 ms. The cycle time of theentire system cannot be faster than the PLC scan time.• Data transfer to and from the tagData Transfer TimeEach frequency and each RFID family have different read/writetimes. The possible data rates depend on the communicationfrequency. A 125 kHz system, for example, offers typicaldata rates of 40/120 bytes per second (write/read) and a highfrequency system offers 130/230 bytes per second. Additionaltime must be calculated for the data transfer on the fieldbusand processing in the PLC. This may be a determining factorfor installation, and will be required if read-on-the-fly speedsneed to be calculated. Typically, the more you want to read themore time it will take.Maximum Passing SpeedThe passing speed is calculated using the data transfer timebetween the tag & head, and the field size. The field size isbased on the size of the read head. The larger the head themore time the tag can stay in the field and the faster the tagcan pass. See the following graphsfor the recommended spacingbetween the tag and the head. Beingtoo close or too far away can reducethe performance of the system.Easy conversions:1m/s = 197 ft/min1m/s = 3.28 ft/secRFID Systems IDENT ControlIDENT ISelection ChartSeries P Series S Series Q Series MV System PFrequency 125 kHz 250 kHz 13.56 MHz 2.45 GHz 125 kHzRead Head Sizes Available 6 3 3 2 1Tag Models Available 25+ 19+ 6+ 1 19+Max Passing Read Only 4 m/s 15 m/s 13 m/s 287m/s 2 m/sSpeed Read Data (4 Bytes) 1 m/s 8 m/s 19 m/s 135m/s .85 m/sMemory Capacity (Bits) 928, 64k 1k 896, 2k 59k 928, 64kMax Read Distance 150 mm 92 mm 300 mm 4000 mm 100 mmMax Write Distance 140 mm 77 mm 250 mm 4000 mm 90 mmMounting In Metal Yes Yes No Yes YesOn Metal Yes Yes Yes Yes YesProtection Class IP68 IP68 IP67 IP67 IP68Bus Serial • • • • •ConnectionsDeviceNet • • • • •PROFIBUS • • • • •Ethernet • • • • •Multiple Tags In Field No No Yes No NoPepperl+Fuchs®Inc. • 1600 Enterprise Parkway • Twinsburg, Ohio 44087-2245 • www.am.pepperl-fuchs.comTelephone (330) 486-0001 • FAX (330) 405-4710 • E-Mail: sales@us.pepperl-fuchs.com19