Allflex AFX-100 Manual do Utilizador descarregar pdf (Página 17)

Rev Australasia V2.3 12/04

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configurations. The balanced nature of this interface provides the ability to achieve long data

communications cable lengths of up to 1500 meters (5000 feet) at the maximum

communications data rate of 57,600 bits/second.

An excellent technical guide to RS422/RS485 communications can be found on, and

downloaded from, B&B Electronics’ Internet web-site at:

http://www.bb-elec.com/tech_articles/rs422_485_app_note/table_of_contents.asp

Users who are planning to connect several Panel Readers on an RS422/RS485 bus should

consult Allflex.

Performance Verification

Using several test eartags of the types to be used with the Panel Reader, the user can verify

read range and read zone area of the installed system by using the green light and beeper as an

indication of when the Panel Reader is correctly reading the eartags. Under optimum

conditions the read ranges listed in Table 4 are typical expected performances.

Table 1 - Nominal Read Distance Performance

Transponder Type / Input Voltage Medium Panel Antenna

600 x 400mm

NLIS – Half Duplex HDX @ 12 VDC 875 mm

HDX / Light Weight Small Stock Tag @ 12 VDC 650 mm

FDX-B Light Weight Small Stock Tag @ 12 VDC 600 mm

Among many influences, the read distance performance of the Panel Reader will be affected

by the following:

Eartag Orientation - For maximum reading distance, the axis of the eartag and reader

antenna coils must be optimally oriented (see Figure 5).

Eartag Quality - Each manufacturer’s eartag differs in (a) the amount of exciter signal

energy necessary to sufficiently operate the eartag’s internal circuitry, and (b) the signal level

of the ID Code information that is returned to the reader. Consequently, it is normal for

eartags of a common type (FDX-B, for example) made by different manufacturers to exhibit

different read range performance characteristics.

Eartag Motion

- The Panel Readers have different size antennas, and the smaller antennas

produce smaller effective “read zones”. Panel Readers are generally designed for reading

eartags while in motion, both translating and rotational. An eartag that is moving quickly

through the read zone while simultaneously changing orientation may not be present within

the reader’s read zone sufficiently long for all the ID Code information to be obtained.

Eartag Size - Physically larger eartags generally contain larger antenna coils which produce

longer reading distances than smaller eartags having small antenna coils.

Eartag Type - HDX eartags (NLIS type tags) generally exhibit greater reading distances than

FDX-B (Small Stock ) eartags of comparable size.

Proximal Metallic Objects - Metal objects located near the eartag or Reader can attenuate

and distort the electromagnetic fields generated in RFID systems, and thus diminish read

distance performance.

Electrical Noise Interference

- RFID eartags and readers use electromagnetic signals as a

premise of operation. Other electromagnetic phenomena, radiated electrical noise from

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