Orion-instruments Eclipse 705 Instrukcja Użytkownika Pobierz pdf (Strona 37)

57-600 Eclipse

Guided Wave Radar Transmitter

2.8 FOUNDATION fieldbus

™

Digital Communications

2.8.1 Description

FOUNDATION fieldbus is a digital communications system

that serially interconnects devices in the field. A Fieldbus

system is similar to a Distributed Control System (DCS)

with two exceptions:

• Although a Fieldbus system can use the same physical

wiring as an existing 4–20 mA device, Fieldbus devices are

not connected point-to-point, but rather are multidropped

on a single pair of wires (referred to as a segment).

• Fieldbus is a system that allows the user to distribute

control across a network. Fieldbus devices are smart and

actually maintain control over the system.

Unlike 4–20 mA analog installations in which the two

wires carry a single variable (the varying 4–20 mA current),

a digital communications scheme such as Fieldbus considers

the two wires as a network. The network can carry many

process variables as well as other information. The ECLIPSE

Model 705FF transmitter is a F

OUNDATION fieldbus regis-

tered device that communicates with the H1 Foundation

Fieldbus protocol operating at 31.25 kbits/sec. The H1

physical layer is an approved IEC 61158 standard. The

figure on page 38 shows a typical Fieldbus installation.

An IEC61158 shielded twisted pair wire segment can be as

long as 6234 feet (1900 meters) without a repeater. Up to

4 repeaters per segment can be used to extend the distance.

The maximum number of devices allowed on a Fieldbus

segment is 32 although this depends on the current draw

of the devices on any given segment.

2.7.4 HART Revision Table

Model 705

HART Version HCF Release Date Compatible with 705 Software

Dev V1 DD V1 July 1998 Version 1.2B and earlier

Dev V1 DD V2 November 1998 Version 1.2C through 1.3D

Dev V3 DD V1 April 1999 Version 1.4A through 1.4C

Dev V4 DD V1 October 1999 Version 1.5 and later

Model 705 2.x

HART Version HCF Release Date Compatible with 705 Software

Dev V1 DD V1 June 2000 Version 2.0A through 2.2C

Dev V2 DD V1 September 2001 Version 2.3A through 2.3E

Dev V3 DD V1 September 2003 Version 2.4A through 2.4B

Dev V4 DD V1 April 2004 Version 2.5A and later

Model 705 3.x

HART Version HCF Release Date Compatible with 705 Software

Dev V1 DD V2 September 2008 Version 3.0A and later

Dev V2 DD V1 August 2011 Version 3.2A and later

1 2 ... 32 33 34 35 36 37 38 39 40 41 42 ... 67 68

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Orion-instruments Eclipse 705 Instrukcja Użytkownika Strona 37

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