Спецификация протокола Profibus

Normative Parts

of PROFIBUS -FMS, -DP, -PA

according to the European Standard

EN 50 170 Volume 2

Edition 1.0

March 1998

®

PROCESS FIELD BUS

PROFIBUS

Specification

PROFIBUS Specification, Order No. 0.032

page 2

PROFIBUS-Specification-Normative-Parts-1:1997

Foreword

PROFIBUS is a fieldbus system, which is in widespread use all over the world.

PROFIBUS fulfils the requirements for the interconnection of intelligent field

devices in manufacturing, process and building automation.

This publication contains the normative parts of the PROFIBUS-FMS / -DP / -PA

specification according to the European fieldbus standard EN 50 170. These

normative parts are supplemented by profiles and guidelines of the PROFIBUS user

organisation (PNO). Both, the normative parts as well as the profiles and

guidelines are published by PROFIBUS International, a world-wide organisation of

more than 650 users of the PROFIBUS technology. PROFIBUS International is

represented by regional user groups in 20 important industrial countries (see

annex).

PROFIBUS has been selected by CENELEC TC65CX to be standardised as European

Standard EN 50170 Volume 2 on 1996-07-02. Therefore, the PROFIBUS specification

has been included without changes in EN 50170. This document is technical

identical to the European Standard EN 50 170 volume 2 and is organised in the

same manner.

PROFIBUS International

Business Office

Haid-und-Neu-Strasse 7

D-76131 Karlsruhe / Germany

Tel: ++ 49 721 9658 590

Fax: ++ 49 721 9658 589

email: PROFIBUS_International@compuserve.com

Internet: http://www.profibus.com

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PROFIBUS-Specification-Normative-Parts-1:1997

Table of Contents of the Normative Parts of the PROFIBUS Specification

Page

Part 1 General Description of the Normative Parts 5

Part 2 Physical Layer Specification and Service Definition 13

Part 3 Data Link Layer Service Definition 49

Part 4 Data Link Layer Protocol Specification 97

(protocol is specified together with services in 3-2)

Part 5 Application Layer Service Definition 139

Part 6 Application Layer Protocol Specification 315

Part 7 Network Management 591

Part 8 User Specifications 687

Part 9 Physical Layer and Data Link Layer for Process Automation 885

Annex Members

Annex BookShop

Annex Support

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PROFIBUS-Specification-Normative-Parts-1:1997

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PROFIBUS-Specification-Normative-Parts-1:1997

PROFIBUS Specification - Normative Parts

Part 1

General Description of the Normative Parts

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PROFIBUS-Specification-Normative-Parts-1:1997

Contents

Page

1 General Description of the Normative Parts ...........................7

1.1 OSI Environment and layers defined ...................................7

1.2 Overview about the layers covered ....................................9

1.2.1 Physical Layer .......................................................9

1.2.2 Data Link Layer ......................................................9

1.2.3 Application Layer ...................................................10

1.2.4 User specifications .................................................11

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PROFIBUS-Specification-Normative-Parts-1:1997

1 General Description of the Normative Parts

This description provides an overview on the models, services and characteris-

tics of the PROFIBUS System.

1.1 OSI Environment and layers defined

The layered structure is based on the ISO/OSI model for open systems communica-

tion (ISO 7498) according to figure 1. This specification defines Layer 1

(Physical Layer, PHY), Layer 2 (Data Link Layer, FDL) and Layer 7 (Application

Layer). The Layers 3 to 6 are empty to minimize expense and increase efficiency.

From/to Application

^

^ !

! ! !

FMS Services FMA7 Services

! ! !

! v v

+-----------------------------------+---------------+

! F M S ! !

! ! !

!... Application Layer ..(Layer 7)..+.... F M A 7 !

! ! !

! L L I ! !

! ! M !

+---------------------------------------+ a !

! ! n !

! empty (Layer 3 to 6) ! a !

! ! g !

+---------------------------------------+---- e ----+

! ! m !

! Data Link Layer (Layer 2) ! e !

! ! n !

! F D L ! t !

! ! !

+---------------------------------------+ F M A 1/2 !

! ! !

! Physical Layer (Layer 1) ! !

! ! !

! P H Y ! !

+---------------------+-----------------+-----------+

!

=========================#=================================

Figure 1. OSI environment

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PROFIBUS-Specification-Normative-Parts-1:1997

This specification defines the technical and functional characteristics of a

serial fieldbus which is aimed at the inter-connection of digital field devices

or systems with low or medium performance, e.g. sensors, actuators, transmit-

ters, programmable logical controllers (PLC), numerical controllers (NC), pro-

gramming devices, local man machine interfaces etc.

Often a field control system is based on a central control and supervision unit,

which is connected to a number of devices and small systems distributed in the

field. In such cases the dominant data transfer is centrally oriented and cyclic

from the field devices to the central data processing unit or to a superior con-

trol system.

Strict realtime requirements have been met using the following simplifications:

- segmentation of long messages (> 235 byte) is not supported.

- blocking of short messages is not supported. The combination of many short

messages into one long message packet is not in accordance with the require-

ment of short messages, and therefore the specification does not provide this

function.

- support of routing functions by the network layer is not provided in the

specification.

- except for a mandatory minimum configuration, arbitrary subsets of services

can be created depending on the application requirements. This is a particu-

larly important aspect for small systems (sensors, etc.).

- other functions are optional such as password protection schemes.

- the network topology is a linear bus with or without terminator, including

drop cables and branches (tree)

- the medium, distances, number of stations Depending on the signal character-

istics, e.g. for shielded twisted pair, ≤ 1,2 km without repeaters, 32 sta-

tions

- transmission speed depends on network topology and line lengths, e.g. step-

wise from 9,6 to 1500 kbit/s

- a second medium (redundancy) is optional

- a halfduplex, asynchronous, slip protected synchronization (no bit stuffing)

is used for transmission

- Data integrity of messages is Hamming distance (HD)=4, sync slip detection,

special sequence to avoid loss and multiplication of data

- Addresses are defined in the range of 0 to 127 (127 = global addresses for

broad-cast and multicast messages), address extension for regional address,

segment address and Service Access address (Service Access Point, LSAP), 6

bit each

- two station types are used: (1) Masters (active stations, with bus access

control), (2) Slaves (passive stations, without bus access control); prefera-

bly at most 32 masters, optionally up to 127, if the applications are not

time critical.

- Bus access is based on a hybrid, decentral/central method; token passing be-

tween master stations and master-slave between master and slave stations. The

token circulates in a logical ring formed by the masters. If the system con-

tains only one master, e.g. a central control and supervision station, no

token passing is necessary. This is a pure single-master/n-slave system. The

minimum configuration comprises one master and one slave, or two masters.

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PROFIBUS-Specification-Normative-Parts-1:1997

- Data transfer services are

(1) Acyclic:

Send Data with/without Acknowledge

Send and Request Data with Reply

(2) Cyclic (Polling):

Send and Request Data with Reply

1.2 Overview about the layers covered

The following describes the functionality of the various layers.

1.2.1 Physical Layer

The Physical Layer (this is the medium, including lengths and topology, the line

interface, the number of stations and the transmission speed, variable in the

range from 9,6 to 1500 kbit/s) can be adapted to different applications. However

there is a common access method and transmission protocol and there are common

services at the user interface.

The Physical Layer (version 1, contained in Part 2 of this specification) is

specified according to the EIA standard RS-485:

- Topology : Linear bus, terminated at both ends, stubs ≤ 0,3 m, no

branches;

- Medium : Shielded Twisted Pair

- Line Length : ≤ 1200 m

- Number of stations : 32 (master stations, slave stations or repeaters)

- Data rates : 9,6 / 19,2 / 93,75 / 187,5 / 500 / 1500 kbit/s

The version 2 (according to IEC 1158-2, contained in Part 9 of this

specification) covers the requirements of Intrinsic Safety (IS):

- Topology : Linear bus, terminated at both ends, spurs ≤ 120 m

- Medium : Twisted Pair or multicore (shielded or unshielded)

- Line Length : ≤ 1900 m depending on cable type

- Number of stations : 32 (master stations, slave stations or repeaters)

- Data rates : 31,25 kbit/s

1.2.2 Data Link Layer

The Medium Access Control protocol (MAC), the data transfer services and the

management services are defined according to the standards DIN 19 241-2, IEC

955(PROWAY C), ISO 8802-2 and ISO/IEC JTC 1/SC 6N 4960 (LLC type 1 and LLC

type 3).

The octet (character) format shall be the UART format FT 1.2 (asynchronous

transmission with start-stop synchronization) as defined for Telecontrol Equip-

ment and Systems (IEC 870-5-1). The transmission protocol definitions are based

on the standard IEC 870-5-2.

The following data transfer services are defined:

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PROFIBUS-Specification-Normative-Parts-1:1997

Send Data with Acknowledge (SDA)

This service allows an user to send data to a single remote station. If an error

occurred, the data transfer shall be repeated.

Send Data with No Acknowledge (SDN)

This service allows an user to transfer data to a single remote station, to many

remote stations (Multicast), or to all remote stations (Broadcast) at the same

time without any confirmation.

Send and Request Data with Reply (SRD)

This service allows an user to transfer data to a single remote station and at

the same time to request data from the remote station. If an error occured, the

data transfer shall be repeated.

Cyclic Send and Request Data with Reply (CSRD)

This service allows an User to cyclically transfer data to a remote station and

at the same time to request data from the remote station.

1.2.3 Application Layer

The Application Layer consists of the two entities FMS (Fieldbus Message Speci-

fication) and LLI (Lower Layer Interface).

1.2.3.1 Fieldbus Message Specification (FMS)

The FMS describes communication objects, services and associated models from the

point of view of the communication partner (server behaviour).

The purpose of communication at the field and process levels is to transfer data

(such reading/writing of measured values, loading/starting/stopping of programs,

processing of events, etc.) between two communicating stations.

For communication between an application process of one device and that of an-

other, the process objects transferred must be made known to the communication

system, which means the process objects must be listed as communication objects

in an Object Dictionary (OD) (comparable to a public telephone directory). Thus,

an application process must make its objects visible and available, before these

can be addressed and processed by the communication services. The application

processes communicating with one another on different devices, however, need

more information than the acknowledgement of the communication objects for effi-

cient communication.

Usually, the stations are located at a distance from one another, or are not ac-

cessible during operation; so they must be uniquely identified with their fea-

tures in the network. Data such as vendor name, model name and profile need to

be read via the bus. Moreover, information on the communication interface status

of the device and on the real device (e.g., indication of servicing dates) are a

very important aspects.

A public Object Dictionary provided by all stations connected to the bus, stan-

dardized device features, identical services and uniform interfaces make up the

basis for open communication between devices of different vendors. This consis-

tent view of a device is called a Virtual Field Device (VFD).

The specification describes the effect of the services on the communication ob-

jects of an application process only for Virtual Field Devices. The mapping of

Virtual Field Devices to real field devices and vice versa is not subject to the

specification. Between the Application Layer and the real application process

lies the so-called Application Layer Interface (ALI).

Спецификация протокола Profibus

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