EKey Fingerscan Access Control System Manual de instalación descargar pdf (Pagina 45)

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ekeyUSA Catalog

2013

ekeyusa_catalog_2012_v7

Page 43

5.8 ekey net Wiring

5.8.1 ekey net Wiring RS485 Bus Topology

The RS-485 bus must be ring shaped bus and not star shaped as per the illustration below. In a ring shaped bus,

all the device daisy-chained starting with the ekey Converter LAN on one end and the ekey net fingerprint

scanner at the other end terminated with 120 ohm resistor. Branches and sub lines should be avoided, but if

used its length should not exceed ~15 ft (5 m).

F i g u r e 21 RS-485 Ring Shaped Bus Connection

F i g u r e 22 RS-485 Star Shaped Bus

Connection - NOT SUPPORTED

5.8.2 ekey net Wiring - Shielding

The type of shielding required depends primarily on the expected distortion on the ekey net wiring. In situations

where electrical distortion is expected, shielding is highly recommended and is required based on the following

scenarios:

• No shielding on ground: in situations with little distortion and

short cable lengths (<10m). e.g. residential homes.

• It will be necessary to use a single-sided grounding (picture 1) in

order to suppress electrical fields.

• Distortions based on a magnetic field can only be suppressed via a

double-sided shielding (picture 2). Negative influences caused by

ground loops are to be avoided!

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EKey Fingerscan Access Control System Manual de instalación Pagina 45