705-5100-F21 datasheet(4/52 Pages) MAGNETROL

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1.0

PROFIBUS PA™ Overview

1.1

Description

PROFIBUS PA™ 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 PROFIBUS PA™ system can use the same physi-

cal wiring as an existing 4–20 mA device, fieldbus devices

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

tidropped and wired in parallel on a single pair of wires

(referred to as a segment).

• PROFIBUS PA™ 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 dig-

ital communications scheme such as PROFIBUS PA™ con-

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

many process variables as well as other information. The

Enhanced Eclipse Model 705PA transmitter is a

PROFIBUS PA™ certified device that communicates with

the DPV1 protocol operating at 31.25 kbits/sec. The MBP

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 seg-

ment is 32 although this depends on the current draw

of the devices on any given segment.

57-645 Eclipse Guided Wave Radar Transmitter - PROFIBUS PA™

Control Room

Power Supply

Terminator

6234 feet (1900 meters) maximum

Terminator

Power

Conditioner

Typical Fieldbus Installation

705-5100-F21 датащи(PDF) 4 Page - Magnetrol International, Inc.