PROFIBUS PADate 09/19/00, Page 1

PROFIBUS PA

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PROFIBUS PA = PROFIBUS for Process Automation

PA is based on the DP and DP Extended protocol

DP Master Class 1 controls both DP AND PA field devices

Definitions for DP protocol also valid for PA:

Parameterization

Configuration

Cyclic data exchange

Diagnostic

...

PROFIBUS PADate 09/19/00, Page 2

PROFIBUS PA

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Physical Setup

Physical layer based on IEC 1158-2

Synchronous data transfer with Manchester coding

Power AND data are transferred via the same wire

Different components for the physical setup (cable, connectors, termination…)

Rules regarding topology and length according to IEC 1158-2

Transmission rate is 31.25kbaud

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PROFIBUS PA

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Physical Setup (continued) - Comparison

PhysicsRS485

wire carries data only

IEC 1158-2

wire carries data and power

Transmission Rate

9,6K; 19,2K; 45,45K; 93,75K; 187,5K; 1,5M; 3M; 6M; 12M

31,25K

NRZ (No Return to Zero) Coding Manchester

11 bits per data byte

1 start bit, 8 data bits (LSB first)

1 parity bit (even parity), 1 stop bit

Character Format

8 bits per data byte

8 data bits (MSB first)

1 parity bit for each character

1 byte FCS check sum (Frame Check Sequence)

Check Sequence

16 bit CRC (Cyclic Redundancy Check)

PROFIBUS PADate 09/19/00, Page 4

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Message Structure

P: 16 Bit PreampleSD: Start DelimiterLE: Net Data Length (DU) + DA, SA , FC, DSAP, SSAPLEr: Length repeatedDA: Destination Address (Where the message goes to)SA: Source Address (Where the message comes from)FC: Function Code ( FC=Type & Priority of Message)DU: Data Unit (Up to 246 Bytes including 2 Bytes for SAP’s)FCS: Frame Checking SequenceCRC: 16 Bit Cyclic Redundancy CheckED: End DelimiterEOF: End Of Frame

SD LE LEr SD DA SA FC DU.. FCS ED

SD LE LEr SD DA SA FC DU.. CRC EOFP SOF

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Character Format

10 0 1 0 0 1 1 0 0 1 1 0 0 0 1 0

Clock

Binary

NRZ(PROFIBUS)

„1“

„0“ 0

0

+

Manchester Bitphase L

(PROFIBUS-PA)

„1“

„0“ 0

0

-

+-

+

0

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PROFIBUSup to 12Mbaud

24 V 24 V

PA Link PA Link

PACoupler

PACoupler

Network Addressing

PROFIBUS45.45kbaud

PROFIBUS PA 31.25kbaud

24 V 24 V

1

2

2

1

PACoupler

3 4 343

11PA

Coupler

XXXX

3

PROFIBUS PADate 09/19/00, Page 7

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Network Topology

PROFIBUS

T Branch

(Main) Line

Star

PROFIBUS PA

24 V

Termination

Spur Line

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Network Topology (continued)

+-

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Network Setup - Rules (continued)

24 V

PACoupler

Up to 31 PA field devices can be

connected to ONE coupler

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Network Setup - Rules

= PA Link = PA Coupler

Up to 5 couplers can be used with one link

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Network Setup - Rules (continued)

24 V

PA Link PACoupler

Up to 31 PA field devices can be connected to ONE

link - INDEPENDENT of the number of couplers

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Network Setup - Rules (continued)

PA Link PACoupler

Maximum current flow per coupler:

400mA for

110mA for EEx [ib] II C ignition protection

90mA for EEx [ia] II C ignition protection

24 V

I

x

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Network Setup - Rules (continued)

24 V

Maximum segment length per coupler = 1,900m

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Network Setup - Rules (continued) (Allowed Length PER Drop/Spur Line)

90

120

30

60

303030

0

20

40

60

80

100

120

140

1..12 13..14 15..18 19..24

[Number of Spur Lines]

Maximum Length(Non Ex) [m]

Maximum Length(Ex) [m]

PROFIBUS PADate 09/19/00, Page 15

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PA Profile

Definition on the application layer level

Profile defines variables, function blocks, meaning of the data, mapping to communication services...

Devices with the same profile implemented can be exchanged

Current version of PA Profile is V3.0

Available as official PROFIBUS International document with order no. 3.042

Pre-defined GSD files for various PA field devices available

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PA Profile (continued)

Measuring range

DP servicescyclic and

acyclic

DP Servicesacyclic

DP servicesacyclic

Profile B

Status

Measured value

Manufacturer-specificparameters

Filter time

Alarm/warning limits

Alarm summary

TAG

(e.g. forpressure

transmitters)

PROFIBUS PADate 09/19/00, Page 17

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Electronic Data Sheets

GSD

GSD File for description of communication parameters

DD

PROFIBUS-PA

PA Field Device Device Description File for

specification of functionality

PROFIBUS Configuration Tool

PROFIBUS Engineering Tool

PROFIBUS PADate 09/19/00, Page 18

PROFIBUS PA

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Engineering Tool

PROFIBUS-PA (31.25 kbaud)

PROFIBUS (up to 12 Mbaud)

Engineering Tool(Diagnostic Master)

Direct access to field device via DP

Extensions (e.g.to change range of

measurement)