705-5100-121 datasheet(4/56 Pages) MAGNETROL

4 / 56 page

1.0

FOUNDATION Fieldbus™ Overview

1.1

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 FOUNDATION 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 and wired in parallel on a single pair of wires

(referred to as a segment).

•FOUNDATION 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 digi-

tal communications scheme such as FOUNDATION fieldbus™

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

many process variables as well as other information. The

Enhanced Eclipse Model 705FF transmitter is a

FOUNDATION fieldbus™ registered 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.

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.

57-640 Eclipse Guided Wave Radar Transmitter - FOUNDATION fieldbus™

Control Room

Power Supply

Terminator

6234 feet (1900 meters) maximum

Terminator

Power

Conditioner

Typical Fieldbus Installation

705-5100-121 Datasheet(PDF) 4 Page - Magnetrol International, Inc.