profibus system description3 english

7/28/2019 PROFIBUS System Description3 English

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PROFIBUS System DescriptionTechnology and Application


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3/30IPROFIBUS System Description

Introduction

The field of industrial communications is continu-ing to develop at an astonishing pace with theresult that the field of automation technology isconstantly changing. Initially, automation focusedexclusively on production, but now it is part of a

network that covers service and maintenance,warehousing, resource optimization and t he pro-vision of data for MES and ERP systems in addi-tion to the actual task of automation.

Fieldbus technology, which has facilitated migra-tion from centralized to decentralized automationsystems and supports the use of distributed intel-ligence, has been the driving force behind thisdevelopment. Ethernet-based communicationsystems link automation technology with infor-mation technology, thus implementing consistentcommunication from the field level to the corpo-rate management level.

Standardized solutions can be found in PROFI-BUS and PROFINET, which provide absoluteconsistency and are highly application-oriented.With its standard protocol, PROFIBUS takes in allsubprocesses found in production and processautomation, including safety-related communica-tion and drive applications, thereby providing theideal basis for ensuring horizontal consistencywithin an automation system. PROFINET alsofeatures a standard protocol which, in addition tohorizontal communication, also supports vertical

communication, thereby linking the field level withthe corporate management level. Both communi-cation systems are, therefore, able to facilitatecross-networked, integrated solutions that areoptimized for the automation tasks concerned.

Since 1989, PROFIBUS has developed into aworldwide leading fieldbus system used in ma-chine and production plant automation. The mainreason why PROFIBUS stands out from otherfieldbus systems is because it offers such an ex-traordinary breadth of applications. Applicationspecific requirements have been integrated intoapplication profiles, and these applications havebeen combined as a whole to create a standard-ized and open communication system. The use ofopen standards instead of proprietary solutionsensures long-term compatibility and expandability,which forms the basis for implementing compre-

hensive investment protection for users and man-ufacturers. This is a v ery important concern ofPROFIBUS & PR OFINET International. Estab-lished worldwide support offers members long-term perspectives.

With well over 30 million devices (as of the end of2009), PROFIBUS is currently present in everybranch of industrial automation and makes animportant contribution to the economic and tech-nological success of the companies.


4/302 PROFIBUS System Description

Table of Contents

1. INTRODUCTION TO PROFIBUS.............. 1

1.1 MARKET POSITION .............................. 11.2 MODULAR DESIGN IN SYSTEM BUILDING

BLOCKS ............................................. 11.3 APPLICATION-SPECIFIC SOLUTIONS....... 21.4 HYBRID AUTOMATION .......................... 31.5 OSI LAYER MODEL AS A BASIS.............. 31.6 STANDARDIZATION .............................. 3

2. TRANSMISSION TECHNOLOGY ............. 4

2.1 TRANSMISSION AS PERRS485 ANDRS485-IS ......................................... 4

2.2 TRANSMISSION AS PER MBP ANDMBP-IS ............................................ 5

2.3 OPTICAL TRANSMISSION ...................... 52.4 WIRELESS TRANSMISSION.................... 52.5 TRANSMISSION TECHNOLOGY IN

HAZARDOUS AREAS............................. 5

2.6 TOPOLOGY......................................... 62.7 REDUNDANCY..................................... 72.8 INSTALLATION INFORMATION FOR

RS485 ............................................. 82.9 INSTALLATION INFORMATION FOR MBP . 82.10 BUS DIAGNOSTICS............................... 9

3. COMMUNICATION WITH PROFIBUS ...... 9

3.1 PROFIBUSDP COMMUNICATIONPROTOCOL ......................................... 9

3.2 DEVICE CLASSES .............................. 103.3 CYCLICAL COMMUNICATION AND

PROFIBUS DIAGNOSTICS................. 113.4 ACYCLICAL COMMUNICATION AND

PARAMETER ADDRESSING .................. 11

3.5 STANDARDIZED FUNCTION BLOCKS (FB)........................................................ 12

3.6 COMM FBS AS A SYSTEM-NEUTRALINTERFACE WITH PROFIBUS ............. 12

4. APPLICATION PROFILES ...................... 13

4.1 PROFIDRIVE .................................... 144.2 PROFIBUSPA(PA DEVICES,"PA

PROFILE") ............................... .......... 144.3 IMPROVEMENTS IN PROFILE 3.02 ......... 144.4 HART ON PROFIBUS ...................... 154.5 PROFISAFE ..................................... 164.6 IDENTIFICATION &MAINTENANCE (I&M)

........................................................ 16

5. DEVICE INTEGRATION .......................... 16

6. QUALITY ASSURANCE ANDCERTIFICATION ................. .................... 17

7. PRODUCT IMPLEMENTATION .............. 19

7.1 STANDARD COMPONENTS ................... 197.2 IMPLEMENTING TRANSMISSION

INTERFACES ...................................... 20

8. USER BENEFITS .................................... 20

8.1 STANDARDIZED AND CONSISTENT........ 218.2 ECONOMY......................................... 218.3 QUALITY CONSCIOUSNESS.................. 218.4 INNOVATION AND PROTECTION OF

PRIVILEGES ....................................... 218.5 GLOBAL SUPPORT.............................. 218.6 FUTURE COOPERATION ...................... 21

9. PROFIBUS & PROFINETINTERNATIONAL (PI) ............................. 22

9.1 RESPONSIBILITIES OFPI ..................... 22

Information on Contents

This system description deals with all the mainaspects of PROFIBUS in 2010 without delvinginto technical details. Please refer to appropriatetechnical literature. In this regard, we would alsolike to point out that, despite the fact that theutmost care was taken while creating thisbrochure, only the normative documents fromPROFIBUS & PROFINET International (PI) are

authoritative and binding.

Chapter 1 contains an introduction of PROFI-BUS and gives the hurried reader an overviewof the market position and technologies used,the modular design and the application-specific solutions made possible by it.

Chapters 2 through 4 deal with the coretechnologies of PROFIBUS (transmissiontechnology, communication and application

profiles) with technical and application-oriented information.

Chapter 5 deals with the topic of device inte-gration and explains the current technologiesused here.

Chapter 6 deals with the topic of certificationand quality assurance of PROFIBUS and ex-plains the process for obtaining a certificate.

Chapter 7 addresses those responsible forproducts and contains information on productimplementation.

Chapter 8 again deals with the most importantfeatures of PROFIBUS and shows how theybenefit users.

Chapter 9 provides information on PROFI-BUS & PROFINET International as the world'slargest interest group for industrial automationwith information on the organization, member-ship, service offerings and global positioning.


5/301PROFIBUS System Description

1. Introduction toPROFIBUS

Automation technology has been characterized byrapidly changing technology for many years. Thedriving force for this was and still is the pressureto lower production costs, the demand for highand consistent product quality, improved operat-ing reliability and the availability and flexibility ofthe systems, especially the consistent flow of datawithin a company. A visible sign of this change isthe development of fieldbus technology with atransition from analog to digital communicationand thus the possibility to exchange detailedinformation on the status of a production systemand its environment very quickly. Digital commu-nication also enables functions of the centralizedcontroller to be relocated to decentralized fielddevices, which simplifies cabling considerably.The world-wide standardization of the interfaces

opens up the path to consistent automation, andleaves previous solutions using a large number ofproprietary systems behind.

PROFIBUS contributed considerably to the de-velopment of fieldbus technology. It links control-lers and control systems with sensors and actua-tors on the field level (field devices) and also ena-bles simultaneous consistent data exchange withsuperordinate systems. PROFIBUS is thefieldbus-based automation standard of PROFI-BUS & PROFINET International (PI). PI has alsodeveloped the PROFINET Ethernet-based auto-mation standard and launched it successfully onthe market. PROFIBUS and PROFINET use iden-tical device profiles, thereby creating investmentsecurity and investment protection for the usersand manufacturers of these technologies. Bothsystems cover the fields of production and pro-cess automation and therefore also enable mixed(hybrid) applications, which are often seen in thepharmaceutical, food andbeverage industries.

PROFIBUS consistency is based on the standard-ized "PROFIBUS DP" communication protocol,which supports a variety of applications in produc-tion automation and process automation as wellas motion control and safety-related tasks. This

integration makes planning, installation and ser-vice easier. Training, documentation and mainte-nance need only be carried out for one technolog-ical aspect.

1.1 Market posi tion

The first fieldbus systems, which were proprietary,were introduced to the market in the 1980s. Withthe objective of far-reaching standardization, 21companies and institutes came together in 1987to create a joint project with the task of developingand testing an open fieldbus standard. This pro-ject was the starting point for the development of

PROFIBUS. After the joint project was complete,the PROFIBUS Nutzerorganisation e.V. (PNO)was founded in 1989 to continue the work. This

organization was comprised of 10 c ompanies,four scientific institutes and ZVEI. Two years later,it grew to over 100 members, and today (2010)there are about 1,400 members who have jointedtogether under the globally positioned PROFIBUS& PROFINET International (PI) fieldbus organiza-tion, which was founded in 1995. Today, there are

27 regional PI associations in countries on everycontinent. The common goal is the continuousdevelopment and global distribution of PROFI-BUS and PROFINET technologies. With well over30 million devices installed in the field, PROFI-BUS is a global market leader in the field of indus-trial communication systems.

The success of PROFIBUS is equally due t o itsadvanced technology and the successful activitiesof the organization, which was founded to repre-sent the interests of manufacturers and users.

In addition to the many measures employed fortechnological development and its propagation,additional global support services for members(users and manufacturers) are available in theform of consulting, information and measures forquality assurance and standardization of thetechnology in international standards.

PI forms the largest user group for industrialcommunication in the world, which offers oppor-tunities for the future and at the same time comeswith certain obligations. The opportunities are inthe creation and propagation of market-leadingtechnologies which are beneficial to the user. Theobligation is for those responsible for this usergroup to fully maintain PROFIBUS's goals of

openness and investment protection in the futureas well. This obligation serves as a guideline foreveryone involved.

1.2 Modular design in systembuilding blocks

PROFIBUS's module concept is what has allowedit to reach its top position in the global market.The communication protocol can be combinedwith a variety of application-specific technologymodules which are compatible with one another(transmission technologies, application profiles,integration technologies). This ensures complete

consistency with a l arge breadth of applications.With such a "system building block" (Figure 1), allthe applications of automation technology cancover tasks in the production and process indus-tries, including safety-related ones.

The core of the system building block is the PRO-FIBUS DP (Decentralized Peripherals) commu-nication protocol, which is the same for all appli-cations and is used for communication betweencentralized automation devices and decentralizedfield devices.

A number of different data transmission alterna-tives are available, depending on the usage case.

RS485 transmission technology is intended foruse in the production industry and in the processindustry in applications without explosion protec-



tion. RS 485-IS (Intrinsically Safe) covers uses inexplosion protected areas. The MBP (Manchestercoded Bus Powered) and MBP-IS transmissiontechnology is specifically oriented toward the pro-

cess industry and also handles power supply todevices on the bus, in addition to data transmis-sion. Several optical transmission technologiesare also available.

PROFIBUS application profiles are specified forstandard data exchange between field devices onthe user level. The use of such profiles guaran-tees interoperability in the data exchange be-tween field devices from different manufacturers.These profiles specify application-typical devicefeatures, and "profile devices" must comply with

them. They might be cross-device-class features(e.g. safety-relevant behavior) or device-class-specific features (e.g. to be exhibited by processdevices or drives). Field devices with differentapplication profiles can be operated in the sameautomation system. S imple devices with univer-sal functionality, e.g. decentralized binary I/O de-vices, do not usually use application profiles.

Additionally to the layers for transmission andcommunication, the system building block alsoprovides the required engineering technologiesfor device description and integration.

1.3 Application-specificsolutions

The system building block makes it possible tocover very different applications using "solutions"specifically arranged for them by combining theappropriate components. Examples includesolutions for the production industry, process au-tomation, drive engineering and s afety-relatedsystems. The structure of these modular"solutions" can be seen in Figure 2. Only thecommunication protocol is the same with allsolutions and ensures the high consistency ofPROFIBUS already mentioned.

Figure 1: PROFIBUS system building blocks

Communication

Technology

Transmission

Technologies

PROFIBUS DP (DP-V0, -V1, -V2)

WiredRS485 / RS485-IS

MBP / MBP-IS

EngineeringTechnologies

GSD

,EDD

,FDT/DTM

,TCI

OpticalGlass, PCF, Plastic

Wireless

PROFIdrive

PADev

ices

Enco

der

Iden

tSys

tems

We

ighing

&

Dosage

HARTon

PROFIBUS

La

bAu

toma

tion

Specific

Appl ication

Profiles

Common

Appl ication

Profiles

XY

. . . .

PROFIsafe, I&M, iPar-Server,

Time Stamp, Redundancy,

Communication

Technology

Transmission

Technologies

PROFIBUS DP (DP-V0, -V1, -V2)

WiredRS485 / RS485-IS

MBP / MBP-IS

EngineeringTechnologies

GSD

,EDD

,FDT/DTM

,TCI

OpticalGlass, PCF, Plastic

Wireless

PROFIdrive

PADev

ices

Enco

der

Iden

tSys

tems

We

ighing

&

Dosage

HARTon

PROFIBUS

La

bAu

toma

tion

Specific

Appl ication

Profiles

Common

Appl ication

Profiles

XY

. . . .

PROFIsafe, I&M, iPar-Server,

Time Stamp, Redundancy,

Blast furnaces are operated without inter-ruption and can only be modernizedat long intervals. This makes especiallyfuture-proof automation technology all themore important. PROFIBUS has provenitself through and through in large-scaleprojects like this.



1.4 Hybrid automation

In the past, production automation and processautomation had to be viewed as two strictly sepa-rate fields and automated using different technol-ogies. The reason for this were the different mar-

ginal conditions of an automation system. Produc-tion automation is based on fast processes andan accordingly shorter system service life. Pro-cess automation, on the other hand, is character-ized by slow procedures and a longer systemservice life. This led to insular solutions within theoverall system. Today, a user can avoid suchinsular solutions by using a PROFIBUS solutionthat is consistent for all the applications of theproduction chain. PROFIBUS is the only fieldbusthat fulfills the requirements of such consistent(hybrid) automation of production-control (inboundand outbound logistics) and process-controlprocess steps (Figure 3).

Examples

In the pharmaceutical industry, the manufactureof medicines is a process-control procedure. Thepackaging of tablets, for example, uses produc-tion-control tasks with complex packagingmachines, however.

In the food industry, at a brewery for example, thetypical process-control procedures in the brew-house and fermenting cellar are followed by theproduction-control procedures of bottle cleaning

and filling and the stacking of crates by robots.

In vehicle production, the paint shop, with its pro-cess-control requirements (explosion protection),is part of a pr oduction chain that otherwise in-volves production-control tasks.

1.5 OSI layer model as a basis

The design of the technology modules with PRO-FIBUS is oriented toward the OSI layer model(Open Systems Interconnection Reference Mod-el). Here, the communication processbetween two nodes is distributed over seven"layers", from layer 1 ("physical layer", trans-mission technology) to layer 7 (application layer,interface to the application). PROFIBUS useslayers 1, 2 and 7 (Figure 4):

Layer 1 defines the physical transmission.With PROFIBUS, there are copper-wireversions (RS485 and MBP) and optical andwireless transmission.

Layer 2 defines the description of the busaccess method, including data security.With PROFIBUS, this is the master-slavemethod in conjunction with the token method.

Layer 7 forms the interface to the applicationand thus represents the link between theapplication and communication.With PROFIBUS, the communication protocolPROFIBUS DP is used here.

The actual application process lies abovelayer 7 and is not part of the OSI model.

Figure 4 shows the definition of the seven

OSI layers on the left and the implementation ofPROFIBUS on the right.

1.6 Standardization

The contents of the OSI layers are specified bystandards so that the openness of the system isensured when the standards are complied with.Together with other fieldbus systems, PROFIBUSis part of IEC 61158 ("Digital data communicationfor measurement and control Fieldbus for use inindustrial control systems") and IEC 61784 ("Pro-file sets for continuous and discrete manufactur-ing relative to fieldbus use in industrial control

systems").

Figure 2: PROFIBUS soluti ons for different marketsegments

Figure 3: Consistent PROFIBUS soluti on in a

single production system

Figure 4: References between OSI model andPROFIBUS

PA Devices

(and others)

Process

Automatio nEx / non-Ex areas

Factory

Auto mation

Safety

Appl icati on

MBP / MBP-IS

RS 485 / 485-IS

Motion

Control

PROFIB US PA PROFIB US DP PROFId ri ve Saf et y

e.g.

Ident SystemsPROFIdr ive PROFIsafe

PROFIBUS

DP

PROFIBUS

DP

PROFIBUS

DP

PROFIBUS

DP

RS 485 RS 485RS 485

MBP-IS

Appl icati on

Profile

Transmission

Technology

Market

Segment

Communication

Technology

PROFIBUS

Solution

(Common term)

PA Devices

(and others)

Process

Automatio nEx / non-Ex areas

Factory

Auto mation

Safety

Appl icati on

MBP / MBP-IS

RS 485 / 485-IS

Motion

Control

PROFIB US PA PROFIB US DP PROFId ri ve Saf et y

e.g.

Ident SystemsPROFIdr ive PROFIsafe

PROFIBUS

DP

PROFIBUS

DP

PROFIBUS

DP

PROFIBUS

DP

RS 485 RS 485RS 485

MBP-IS

Appl icati on

Profile

Transmission

Technology

Market

Segment

Communication

Technology

PROFIBUS

Solution

(Common term)

Identifying

Conveying

Storing

Checking

Filling

Conveying

Storing

Packing

Mixing

Drying

Separating

Heating

InboundLogistics

ProductionProcesses

OutboundLogistics

PROFIBUSPROFIBUS PROFIBUS

Production flow

PROFIBUS

User program

7 Application Layer

6 Presenta tion Layer .

5 Session Layer

4 Transport Layer

3 Network Layer

2 Data link Layer

1 Physical Layer

Application profiles

OSI Layer Model

Not used

PROFIBUS DP Protocol

(DP-V0, DP-V1, DP-V2)

OSI implementation at PROFIBUS

Fieldbus Data Link (FDL):Master Slave principle

Token principle

Transmission technology



IEC 61158

IEC 61158 deals with the technologies used anddescribes the method of functioning of thefieldbus. It is divided according to the OSI model.The individual fieldbuses are differentiated by thedefinition of "fieldbus protocol types" in this stand-ard. Here, PROFIBUS is type 3 and PROFINETtype 10.

IEC 61784

IEC 61784 defines the subsets of the service andprotocol supersets specified in IEC 61158 (andother standards) which are used by a certain

fieldbus system for its communication. They arecollected in "Communication Profile Families(CPF)"; for PROFIBUS, it is "Family 3" with asubdivision into 3/1 (RS485 and fiberoptics) and3/2 (MBP). Part 3/3 is concerned with PROFINET.

2. Transmissiontechnology

2.1 Transmiss ion as per RS485and RS485-IS

The easy-to-use and cost-effective RS485 trans-mission technology is preferred for use with taskswhich require a hi gh transmission speed, butwhich do not require explosion protection (intrinsicsafety). It is widely used in the production industryand is also found in parts of the process industry.A twisted, shielded copper cable with a pa ir ofwires is used. The bus structure enables non-reactive coupling and decoupling of stations andincremental commissioning of the system. Subse-quent system expansions do not affect stationsalready in operation within certain specified limits.Details can be found in Table 1 and Table 2.

In compliance with certain values, the use of theRS485 interface with its high transmission rates isalso possible in intrinsically-safe areas (RS485-IS). When the interface was specified, the levelsfor the current and voltage, which must becomplied with by each individual node to ensuresafe functioning when connected together, weredefined. Within a circuit, certain maximumcurrents are permissible with a set voltage. Whenconnecting active sources together, the totalcurrent of all the nodes may not exceed the max-imum permissible current. The difference betweenthis concept and the FISCO model (see 2.5) withonly one intrinsically-safe source is that all nodes

represent active sources here.

Table 1: Overview of transmissio n values

RS485 RS485-IS MBP MBP-IS Fiber Optic

Data transmission

Digital; differential

signals acc. to RS485,

NRZ (no return to zero)

Digital; differential

signals acc. to

RS485, NRZ

Digital, bit-

synchronous,

Manchester coding

Digital, bit-

synchronous,

Manchester coding

Optical, digital, NRZ

Transmission rate 9.6 to 12000 Kbit/s 9.6 to 1500 Kbit/s 31.25 Kbit/s 31.25 Kbit/s 9.6 to 12000 Kbit/s

Data security

HD=4; parity bit;

start/end delimiter

HD=4; parity bit;

start/end delimiter

Preamble; fail-safe

start/end delimiter

Preamble; fail-safe

start/end delimiter

HD=4; parity bit;

start/end delimiter

Cable

Twisted, shielded two-

wire cable,

cable type A

Twisted, shielded

two-wire cable,

cable type A


wire cable,

cable type A


wire cable,

cable type A

Multi- and single

mode glass fiber;

PCF; plastic fiber

Remote power

supply

Possible using

additional cores

Possible using

additional cores

Optional using signal

cores

Optional using signal

cores

Possible using hybrid

cable

Ignition protection

types

None Intrinsic safety

Ex ib

None Intrinsic safety

Ex ia/ib

None

Topology

Line topology with

termination

Line topology with

termination

Line topology with

termination

Line and tree topology

with termination; also

combined

Star and ring topology

typical; l ine topology

possible

Number of nodes

Up to 32 nodes per

segment. Max. total

126 per network

Up to 32 nodes per

segment. Max. total

126 per network

Up to 32 nodes per

segment. Max. total

126 per network

Up to 32 nodes per

segment. Max. total

126 per network

Up to 126 nodes per

network

Number ofrepeaters

Max. 9 with s ignal

refreshing

Max. 9 with s ignal

refreshing

Max. 4 with signal

refreshing

Max. 4 with signal

refreshing

Unlimited with signal

refreshing; note signal

propagation delay

The supply of clean water requires majorinvestment in existing and new wastewater treatment plants. Maximum availabil-ity and optimum utilization of processtechnology are required. PROFIBUS is thepreferred solution of many planners andoperators in th is area.



2.2 Transmiss ion as per MBPand MBP-IS

MBP (Manchester Coded, Bus Powered) trans-mission technology implements the simultaneoussupply of power to the connected field devicesand communication of the data over a single ca-ble, i.e. directly via the bus medium. This enableswiring overhead to be significantly reduced, meetsrequirements for much simpler and safer installa-

tion and boasts all the benefits of digital transmis-sion down to the field device. MBP was specifical-ly developed to meet the demands of processautomation and is standardized in IEC 61158-2.Details can be found in Table 1 and Table 3.

In the MBP-IS version, this transmission technol-ogy is especially suitable for use in hazardousareas and is therefore widely used in applications

of the chemical, oil and gas industries. Explosionprotection is implemented via limiting power in the

incoming bus supply or more frequently in theinstallation components in the field. Working onfield devices during active operation is made pos-sible, for example, by means of intrinsically safeignition protection. The easiest way to be verifiedfor intrinsic safety is to go through models such asFISCO or Entity. If all the components used con-

form with the standards, no further calculationsare necessary.

2.3 Optical transmission

There are fieldbus usage conditions under whichwired transmission technology reaches its limits,for example in an environment with heavy inter-ference or when bridging long distances. In thesecases, optical transmission via fiberoptic cables isavailable. The corresponding PROFIBUS guide-line specifies the technology available for this.When the specifications were being made, it wasensured that existing PROFIBUS devices could

be integrated into a fiberoptic cable network with-out adverse affects. This ensures compatibilitywith existing PROFIBUS installations.

The supported fiberoptic cable fiber types areshown in Table 4. Due to the transmission charac-teristics, typical topology structures are the starand the ring; linear structures are also possible.The implementation of a fiberoptic cable networkin the simplest case involves the use of electro-optical converters which are connected to the fielddevice with the RS 485 interface and the fiberop-tic cable on the other side. This also makes itpossible to switch between RS 485 and fiberopticcable transmission within an automation system,

depending on the prevalent conditions.

2.4 Wireless transmission

PROFIBUS is also used in wireless communica-tion. Even if PI has not made any provisions in theform of specifications or guidelines, interoperabil-ity with wired systems is still ensured. This is sup-ported by the many applications in use.

In PROFIBUS systems, solutions for the wirelessconnection of sensors and actuators are alsopossible. Corresponding guidelines which specifythe integration of WirelessHART (used in processautomation) and Wireless Sensor/Actuator Net-work (WSAN, used in production automation) arein process.

2.5 Transmission technology in

hazardous areasWhen operating fieldbuses in hazardous areas,the interface PROFIBUS MBP is the typical

Table 2: Transmiss ion values of RS485 and MBP

Table 3: Characteristics of MBP and MBP-IS

Table 4: Supported fiberoptic cable types

Transmission rate

[Kbit/s]

Transmission

range per

segment [m]

Appl ies to

9,6 19,2

45,45 93,751200 RS485

187,5 1000 RS485

500 400 RS485

1500 200 RS485

3000 6000 12000 100 RS485

31,25 1900 MBP

Wave resistance

Capacitance per unit

Loop resistance

Core diameter

Core cross-section > 0,34 mm2

135 ... 165

30 pf/m

110 /km

> 0.64 mm

The values above apply to cable type A with the following

properties

Fieldbus standard IEC 61158-2 for

MBP transmission t echnology

Up to 32 nodes in one segment

Data transmission rate 31.25 Kbit/s

Per field device: Min. working voltage 9 V DC

Min. current consumption 10 mA

Transmission of digital communication signal in zero-mean

Manchester II coding (MBP) through 9 mA amplitude

Signal transmission and remote power supply using twisted-pair

cable

Fieldbus cable type A

Connection of field devices via stubs (spur) to a main cable

(trunk) for trouble-free disconnection of devices without affecting

other nodes

Max. total length of main cable, including all stubs, is 1900 m

Fiber type Core diameter [m] Transmission range

Multi-mode glass fiber 62,5 / 125 2 - 3 km

Single-mode glass fiber 9 / 125 > 15 km

Plastic fiber 980 / 1000 Up to 100 m

HCS fiber 200 / 230 Approx. 500 m



choice. Besides the IEC 61158-2 (fieldbus stand-ard, Table 3), the more stringent explosion protec-tion standard IEC 60079-11 (electrical equipmentfor hazardous areas) must be observed. H eretwo concepts are principally used

The FISCO model (IEC 60079-27) enables the

implementation of explosion protection, includ-ing regulatory approval without individualcalculations. It is characterized, however, by aconsiderable low input power into a segmentand thus by short cable length and low num-ber of field devices.

The High-Power Trunk concept, whereby thelimitations in power of FISCO are removed byusing the ignition protection type increasedsafety. Intrinsic safety is applied where work-ing on field devices is permitted also withouthot work permit.

In certain cases, the RS485 interface in compli-

ance with Ex e ignition protection type can also beused in the hazardous area.

The FISCO model (IEC 60079-27)

The FISCO model (Fieldbus Intrinsically SafeConcept) makes it easy to plan, install andexpand PROFIBUS networks in hazardous zonesof type 1. This model is based on the specificationthat a communication network is intrinsically safeand does not require calculations for validatingintrinsic safety if the relevant components, suchas the field devices, cables, segment couplersand bus termination values conform to a set oflimit values (for voltage, current, output, inductivity

and capacity). Intrinsic safety is considered veri-fied if all the components operated in the segmentin question are certified as per FISCO. The follow-ing constraints have also be met:

Each segment only has one power supplysource

The total cable length is up to 1000 m

FISCO ensures that

The field devices always act as passive sinks

the permissible input values of each field de-vice are greater than the possible and permis-sible output values of the associated supply

unit if a fault were to occur.

The ignition protection type intrinsic safety Ex i(IEC 60079) is the most often used protectiontype in measurement and control technology. It isbased on the parameter of limiting current andvoltage in intrinsically safe circuits to levels whereneither thermal effects nor sparking could lead tothe ignition of explosive mixtures. This is associ-ated with a limitation of the supply current of a PAsegment to 100 mA with corresponding limitationsin cable length and the number of bus nodes.

The High-PowerTrunk Concept

The "intrinsically safe" ignition protection type isonly really required in a pr ocess control systemwhere access is required for maintenance or

device replacement during operation. In otherareas, e.g. at the trunk cable, this requirementgenerally does not apply, which is why ignitionprotection type Ex e (increased safety) is appliedthere with the ability to transport more power. Thisenables longer cable length and i ncreasednumber of field devices without obstructing opera-

tion. It is therefore possible to use a mixedconcept comprised of protection types increasedsafety (Ex e) for the trunk and intrinsic safety (Exi) at the spur, which can be implemented withdevices called fieldbus barriers. The outputs ofthe field barriers are conventionally intrinsicallysafe for the connection of field devices. An over-view on this can be found in Figure 5.

Likewise, in automation systems with hazardard-ous zone 2, the trunk is designed in the "non-sparking (Ex nA)" protection type and t hus

enables the introduction of high currents into zone2. Due to the less stringent explosion protectionrequirements simple field distributors can be usedhere instead of field barriers. Field devices of pro-tection type "energy limited" (Ex nL) can beconnected to their short circuit-proof outputs of 40mA output current each.

2.6 Topology

If RS485 transmission technology is used , allfield devices are typically connected in a l inestructure (see Figure 6) with up to 32 nodes (mas-ter and slaves) in one segment. The beginningand end of each segment are provided with activebus termination, which must be supplied withpower continuously. The bus terminations areusually implemented as optionally activatable inthe devices or plugs. If there are more than 32nodes or the network span is being extended,repeaters must be used to l ink the networks.

Figure 5: Utilization of different ignition protectiontypes

T

Field devices

Terminator

Segment coupling

and power supply

PROFIBUS DP

PROFIBUS PA

Spur: EEex i

Trunk: EEx e

Zone 1 (EEx e)

Zone 1 (EExi )

General Purpos e (safe) area

Field barriers

Zone 0

T

Field devices

Terminator

Segment coupling

and power supply

PROFIBUS DP

PROFIBUS PA

Spur: EEex i

Trunk: EEx e

Zone 1 (EEx e)

Zone 1 (EExi )

General Purpos e (safe) area

Field barriers

Zone 0



If MBP transmission technology is used (inprocess automation), basically any topology ispermissible. Linear and tree structures and com-binations of both are thus possible. In practice,

the "trunk & spur topology" (see Figure 6) hasestablished itself as the de-facto standard, as it isespecially clear and well-laid-out. Thanks to thetechnically-mature installation technologies avail-able on the market, it also exhibits a high degreeof robustness. The overall length of a segmentmay not exceed 1,900 meters, and the length ofthe stubs in intrinsically-safe applications is max. 660 m and must be taken into account when calcu-lating the overall length.

Coupling RS485 and MBP transmission tech-nology. The MBP transmission technology istypically limited to certain subsegments of a sys-tem, e.g. a group of field devices in a hazardous

area. The connection of such subsegments (des-ignated as MBP or PA segment or PA spur) to theRS485 segment (also designated as DP segmentor DP spur) is carried out using segment couplersor links. They handle the following tasks:

Implementation of the asynchronous signalencoding with RS485 into synchronous signalencoding with MBP

Provision of incoming supply voltage for thePA segment and limiting of incoming currentsupply

Decoupling of transmission speed

Isolation and power limiting for hazardous ar-

eas (optional)

Segment couplers are transparent from thestandpoint of the bus protocol, the devices of theMBP segment are directly visible on the DP sideand the segment coupler itself does not requireconfiguration.

Links, on the other hand, are intelligent and mapall devices connected in the MBP segment as asingle slave in the RS485 segment. The linkneeds to be configured and restricts the totalamount of data which can be transferred to andfrom the connected devices to 244 by tes. Thecyclical data from the PA devices is compressed

into a single DP telegram on the DP side andmust be reselected by the DP master. The fasterDP segment enables a number of PA segments

to be integrated into a single DP network viasegment couplers or links.

2.7 Redundancy

For applications which demand high systemavailability, such as with continuous processes,redundant systems are generally used, wherebythe redundancy can extend to all system compo-nents. A differentiation is made between differentconcepts which can be combined with one anoth-er as desired and, in special cases, also containcomplete spatial separations:

Master redundancy:The control system or the controller is de-signed redundantly (system redundancy,Figure 7, right)

Media redundancy:The cable paths are designed redundantly

Coupler/link/gateway redundancy:The segment couplers are designed redun-dantly (Figure 7) If a coupler fails, the otherones seamlessly take over its function. Themaster does not notice the switchover and nomessages are lost.

Figure 6: The connecti on of DP and PA segments

Figure 7: Various redundancy concepts

T

T

Field devices

Field distributors (barriers) Terminator

Segment coupling

and power supply

PROFIBUS DP

PROFIBUS PA

Trunk

Spur

Field devices

(Slaves)

T

Controller

(Master)

T

T

Field devices

Field distributors (barriers) Terminator

Segment coupling

and power supply

PROFIBUS DP

PROFIBUS PA

Trunk

Spur

Field devices

(Slaves)

T

Controller

(Master)

Host Host

DP-MasterDP-Master

Flying Redundancy combined withSegment Coupler Redundancy

Segment coupler

Segment coupler

Host

DP-Master

Segment Coupler Redundancywith single host

Segment coupler

Segment coupler

PROFIBUS PA

PROFIBUS

DP

PROFIBUS PA

PROFIBUS

DP

Host Host

DP-MasterDP-Master

Flying Redundancy combined withSegment Coupler Redundancy

Segment coupler

Segment coupler

Host

DP-Master

Segment Coupler Redundancywith single host

Segment coupler

Segment coupler

PROFIBUS PA

PROFIBUS

DP

PROFIBUS PA

PROFIBUS

DP

Drive technology is required for every au-tomation task: Whether it's moving, adjust-ing, positioning, conveying or storing, it alldemands perfect communication betweendrives and the automation system. Notechnology in the world is used more thanPROFIBUS here.



Ring redundancyThe combination of redundant couplers andfield devices with active field distributorsimplements ring redundancy and creates ex-panded media redundancy. Subsegmentswhich have become defective due to a shortcircuit or wire break are automatically and

seamlessly operated further via a couplereach in a line structure (Figure 8).

Slave redundancy:The field devices or the PROFIBUS connec-tion in the field device are designed redun-dantly. Concepts for slave redundancy aredescribed in the PROFIBUS specification titledSlave Redundancy. Field devices designedwith redundancy need to be on an equal foot-ing and determine between themselves whichis to act as the primary node and which as thesecondary node. Manufacturer-specific solu-tions are available for transmission media andmasterredundancy.

2.8 Installation informationfor RS 485

A number of different cable types (type designa-tion A through D) for different usage cases areavailable for the connection of devices to oneanother and to network elements (e.g. segmentcouplers, links and repeaters). If the RS485transmission technology is used, cable type A(data in Table 2) is strongly recommended.

When connecting the nodes, ensure that the datacables are not mixed up. To achieve high interfer-ence resistance of the system against electro-magnetic radiation, a shielded data cable (type Ais shielded) should definitely be used. The shield-ing is to be connected to the protective ground onboth sides ensuring good conductivity via large-area shield clamps. Equipotential bonding of allconnected field devices is also recommended.Also ensure that the data cable is laid as far awayfrom all high-current cables as possible. Stubsmust absolutely be av oided with transmissionrates greater than or equal to 1.5 MBit/s. Thenumber of nodes which can be connected to asegment is limited to 32.

The plugs offered on the market enable incomingand outgoing data cables to be connected directlyin the plug. This avoids stubs, and the bus plugcan be connected to and disconnected from thebus at any time without interrupting the data traf-fic. The plug connectors suitable for RS485transmission technology differ by protection type.

In protection type IP 20, a 9-pin D-Sub plug con-nector is preferable for use. In protection type IP65/67, different solutions are recommended asper the guideline:

M12 round plug connector as perIEC 60947-5-2

Han-Brid plug as per DESINA recommendation and

Hybrid plug connector

7/8" plug

The hybrid plug systems also include a variant fortransmitting data over fiber-optic cable fibers and

24 V operating voltage for the peripheral devicesvia copper cables in a single hybrid cable.

Experience shows that difficulties with the trans-mission technology in PROFIBUS networks canmost often be traced back to improper cablingand installation. Bus test devices, which can ferretout many typical cabling errors before commis-sioning, can remedy this situation.

The reference addresses of the many differentplugs, cables, repeaters and bus test devices canbe obtained from the PROFIBUS product catalog(www.profibus.com).

2.9 Installation informationfor MBP

The intrinsically safe MBP transmission technolo-gy is normally limited to certain subsegments(field devices in the hazardous area) of a systemwhich are then linked to the RS485 segment (con-trol system and engineering devices in themeasuring station) via segment couplers or links.

As already mentioned, segment couplers aresignal converters which adapt the RS485 signalsto the MBP signal level and vice versa. They aretransparent from the viewpoint of the bus proto-

col.

Links, on the other hand, are intelligent. Theymap all field devices connected in the MBP seg-ment upwardly as a single slave in the RS485segment; downwardly, it functions as a master. Iflinks are used, the transmission rate in the RS485segment is not influenced by the connected PAsegments. This also allows fast networks to beimplemented using field devices with an M BPconnection for control tasks, for example.

A two-wire shielded cable (type A) is used as thetransmission medium. The bus' main cable isprovided with passive line termination at both

ends. The bus termination is already permanentlyintegrated at the segment coupler or link. A fielddevice using MBP technology which is connected

Figure 8: Ring redundancy with PROFIBUS PA

PROFIBUS PA

DP/PA Link (redundant)

PROFIBUS

DP

Acti ve field dis tri buto rs

PROFIBUS PA

DP/PA Link (redundant)

PROFIBUS

DP

Acti ve field dis tri buto rs



with wrong polarity in most cases does not nega-tively affect the functionality of the bus, as thesedevices are normally equipped with automaticpolarity detection.

A typically free of charge planning softwareshould be used for segment design.

(www.segmentchecker.com) Hereby the electricalfunction of a segment can be checked before in-stallation work starts. Planning and checkingsteps comprise cable length and number ofdevices possible. This planning procedureprotects the user from possible costly subsequentmodifications of the installation.

The operation of bus-supplied and ex ternally-supplied devices together is permissible. Notethat externally-supplied devices draw a bas ecurrent via the bus connection, which must betaken into account accordingly when calculatingthe maximum available supply current.

2.10 Bus diagnostics

Bus diagnostics enables the physical layer to bemeasured on a segment- and field device-specificbasis and simplifies commissioning. Once installa-tion is complete, the loop check is carried out atthe push of a bu tton using corresponding toolsavailable on the market. Extensive expert knowledge about waveforms and possible causes areno longer required for commissioning.

Although simulated aging tests of installations didnot show any relevant risks, there are other,substantive reasons for continuous monitoring of

the physical layer itself. The most common causeof changes on a fieldbus installation areauthorized interventions during maintenance orassembly operations, more so than unwantedchanges due to environmental conditions. Allimportant parameters affecting transmissionquality are monitored using diagnostics tools toensure that they remain within permissible limits.

By integrating bus diagnostics into the powersupply technology, it becomes possible to monitorsystems permanently rather than just sporadically,thereby facilitating the identification of errorswhich might otherwise slip through unnoticedduring operation. This also makes it possible to

detect changes on t he physical layer and r ectifyerrors which might cause the bus to fail. Busdiagnostics also make troubleshooting mucheasier, as maintenance personnel are providedwith detailed information, often with information inplain text, about possible errors.

Notice: Explanations of field device diagnosticsare found in Chapter 4 under "PA profile".

3. Communication withPROFIBUS

PROFIBUS devices communicate using thePROFIBUS DP (Decentralized Periphery) com-munication protocol, which is the same for all ap-plications and which allows cyclical and acyclicalcommunication and s pecifies rules for this. Thecore of the communication process is the master-slave method, where a master (active communi-cation nodes: PLC, PC or control system) cyclical-ly prompt the connected slaves (passivecommunication nodes: field devices, I/Os, drives)to exchange data. The polled slave answers theprompting master with a r esponse message. Arequest message contains the output data, e.g.setpoint speed of a drive, and the associated re-sponse message contains the input data, e.g. thelatest measured value from a sensor. A bus cyclecomes to an end once all connected slaves have

been polled in order.

In addition to this cyclical communication for thefast exchange of input and output data betweenthe master and slaves at regular intervals, need-based data can also be transmitted using PRO-FIBUS, e.g. device setting data. A master has theinitiative, accessing the data of a slave in read orwrite mode acyclically. There can be more thanone master in a PROFIBUS system. In such acase, the access authorization passes from theactive master to the next master (token-passingprinciple).

3.1 PROFIBUS DP communica-tion protocol

For optimum fulfillment of the requirements ofdifferent areas of use, the functions of the PRO-FIBUS DP communication protocol aredistributed over three performance levels: DP-V0,DP-V1 and DP-V2 (Figure 10).

Version DP-V0 provides the basic function of thecommunication protocol. This includes, in particu-lar, cyclical communication and device-, module-and channel-specific diagnostics for quick faultlocalization. Examples of this include "excesstemperature" and "short circuit on output".

Figure 9: Cyclical and acyclical communicationwith DP-V1

DP Slave 1

PROFIBUS DP

Master Class 1

PROFIBUS DP

Master Class 2

DP Slave 2 DP Slave 3

Token

Slave 1 Slave 3Slave 2 Slave 3

Cyclic Access

( Master 1)

Acyclic Access

(Master 2)

.....

Cycle

DP Slave 1

PROFIBUS DP

Master Class 1

PROFIBUS DP

Master Class 2

DP Slave 2 DP Slave 3

Token

Slave 1 Slave 3Slave 2 Slave 3

Cyclic Access

( Master 1)

Acyclic Access

(Master 2)

.....

Cycle



Version DP-V1 supplements DP-V0 with functionsfor acyclical communication, i.e. for functions suchas parameterization, operation, monitoring andalarm handling. DP-V1 enables online access tobus nodes via engineering tools for this purpose(Figure 9).

Version DP-V2 contains additional functions asextensions of DP-V1, in particular functions whichare required for drive control. These includefunctions for communication between slaves, cy-cle synchronization and time stamping.

Field devices for process automation are typicallyslaves of performance level DP-V1 and can there-fore communicate acyclically to set device pa-rameters.

3.2 Device classes

PROFIBUS devices are divided into three classesbased on their functions:

PROFIBUS DP master (class 1)

A PROFIBUS DP master of class 1 (DPM1) is amaster which uses cyclical communication toexchange process data with its associated slaves.Devices of this type are often integrated in amemory-programmable controller or an aut oma-tion station of the process control system.

PROFIBUS DP master (class 2)

A PROFIBUS DP master of class (DPM2) was

originally defined as a master used as a tool inthe context of PROFIBUS system commissioning.In the course of the DP-V1 and DP-V2 functionalexpansions, a DPM2 has been more specificallydefined as a master which can be used to setdevice parameters via acyclical communication.Devices of this type are usually part of an engi-neering station used for device configuration. ADPM2 need not be permanently connected to thebus system.

Figure 10: PROFIBUS DP protocol, performance levels

Time

Functional Levels

DP-V2 Data Exchange Broadcast (Publisher / Subscriber)

Isochronous Mode (Equidistance

plus extensions:

Clock Synchronization & Time Stamps HART on PROFIBUS

Up/Download (Segmentation)

Redundancy

DP-V1

Acycl ic Data Exchange between PC or PLC and Slave Devices

plus extensions:

Integration within Engineering: EDD and FDT

Portable PLC Software Function Blocks (IEC 61131-3) Fail-Safe Communication (PROFIsafe)

Alarms

DP-V0

Cyclic Data Exchange between PLC and Slave Devices

plus extensions:

GSD Configuration Diagnosis

DeviceFeatures

Time

Functional Levels

DP-V2 Data Exchange Broadcast (Publisher / Subscriber)

Isochronous Mode (Equidistance

plus extensions:

Clock Synchronization & Time Stamps HART on PROFIBUS

Up/Download (Segmentation)

Redundancy

DP-V1

Acycl ic Data Exchange between PC or PLC and Slave Devices

plus extensions:

Integration within Engineering: EDD and FDT

Portable PLC Software Function Blocks (IEC 61131-3) Fail-Safe Communication (PROFIsafe)

Alarms

DP-V0

Cyclic Data Exchange between PLC and Slave Devices

plus extensions:

GSD Configuration Diagnosis

DeviceFeatures

DeviceFeatures

Manufacturers of fine chemicals must re-spond flexibly and quickly to customerorders and frequently adapt their systemsaccordingly. Thanks to its enormous flexi-bility, PROFIBUS offers the best prerequi-site for this.



PROFIBUS slave

A PROFIBUS slave is a passive communicationnode which reacts to prompts from the master bysending a response message. Devices in thisclass are usually field devices (remote I/O, drive,valve, transducer, analyzer) which acquire pro-

cess variables or play a part in the process bymeans of manipulated variables. A differentiationis made between compact and modular slavedevices. A modular device comprises a h eadstation containing the fieldbus interface and anumber of slots into which various modules canbe inserted. By combining different modules,modular slaves can be a dapted flexibly torespond to prevailing requirements with regard toinput and output data. Compact devices have afixed set of input and output data comparable toa modular device with precisely one permanentlyinstalled module.

The majority of slave devices in process automa-

tion are modular devices on which, rather thanbeing physically present, the individual modulessimply exist in the device software (virtual mod-ules). These virtual modules (and, therefore,access to the associated input and output data)are activated or deactivated when cyclic commu-nication is established. The virtual modules ofwhich a s lave device in process automation isable to make use are specified in the deviceprofile for PA devices.

Frequently, PROFIBUS master devices supportthe functions of both a DPM1 and a DPM2. Simi-larly, there are also automation devices which are

able to operate as both masters and slaves. Inpractice, it is rarely possible to unequivocallycategorize physical devices into the function clas-ses outlined above.

3.3 Cyclical communication andPROFIBUS diagnostics

Once the configuration has been loaded on theclass 1 master with the help of the configurationtool, the master establishes cyclical communica-tion with the associated slave devices (MS0channel). During this power-up phase, the slaveadopts a two-stage approach to checking the con-

figuration data received from the master.First, the parameters set in the configuration (e.g.master address, watchdog time and ID number)are transferred to the slave (parameterization)and checked (configuration). The ID number isunique for each device type and is assigned byPI. Cyclical communication can only take place ifthe ID number from the configuration tallies withthe ID number saved in the slave. Next, the infor-mation about the configured modules in otherwords, the configuration bytes is transferred tothe slave and checked. Cyclical communicationcan only be established if the modules which arephysically present tally with those set in the

configuration or if the device can adapt to theconfiguration received.

Successful establishment of communication isthen verified via the requested diagnostics data.The slave reports invalid parameter or configura-tion data to the master through correspondingerrors in the PROFIBUS standard diagnostics. Ifthe parameter and configuration data is valid, themaster will initiate cyclical communication with the

slave device.

PROFIBUS diagnostics comprise both PROFI-BUS-specific standard diagnostics and advanceddiagnostics. The latter contains device-specificdiagnostics data relating, for example, to measur-ing or setting procedures. Any changes to device-specific diagnostics data are reported by a slavein the response message during cyclical commu-nication; the master will respond accordingly inthe next bus cycle by polling the diagnostics data,rather than the process data, of the slave con-cerned. Each PROFIBUS slave can only engagein cyclical data exchange with one D PM1. This

ensures that a slave can only receive output datafrom one master, thereby avoiding data incon-sistency.

3.4 Acyclical communication andparameter addressing

A key part of the acyclical data exchange processis the writing or reading of device parameters atthe behest of the master. These device parame-ters can be used by a centralized operator tool toconfigure a field device, thereby adapting it to thespecific task it has been charged with performingin the technical process.

There are two different channels for acyclicalcommunication, MS1 and MS2. In this context, alink between a master and a slave (MS1 link) viathe MS1 channel can only ever be established ifcyclical data exchange is taking place betweenthe master and slave concerned.

As a slave is only able to exchange data cyclicallywith one master at once, a slave can only have upto one MS1 link. Subject to corresponding param-eterization data, the MS1 link is establishedimplicitly when cyclical communication is initiatedand monitored by the watchdog time.

A slave can have an M S2 link with one or anumber of masters simultaneously as long as it isnot engaged in cyclic communication. The MS2connection has to be established explicitly by themaster. It has a separate time monitoring mecha-nism by means of which an MS2 link will beclosed if it is not used for a set period of time.Unlike for cyclical communication, a complexconfiguration based on the device master file isnot required for acyclical communication; usually,knowledge of the address of the deviceconcerned is all that is needed to establish anMS2 link on the master side.

Device parameters are addressed in a slave

device by means of the specification of the slotand index. The "slot" (values from 0 to 254) is aslot on a m odular device; on PA devices, a s lot



addresses a function block (see Chapter 4). The"index" (0 to 254) is the address of a parameterwithin the slot concerned.

Devices with PA profile 3.0 and higher must havean MS2 channel, although the MS1 channel isoptional. Since, in practice, very few PA profile

devices implement an M S1 channel, the MS2channel is used universally for acyclical datatransmission in process automation.

3.5 Standardized functionblocks (FB)

When developing and using cross-manufacturerapplication profiles, the technology of the stand-ardized function blocks (FB) plays an i mportantrole, because the growing functional scope ofmodern field devices allows different controllers tobe integrated without specific communicationknowledge and without manufacturer-specific

adaptations to the application program. Functionblocks, which contain the sometimes complexfunctions of field devices (e.g. calibration, motorpower-up, speed change etc.) in encapsulatedform, are used for this. They therefore function asa "representative" (Proxy FB) of the correspond-ing field devices placed in the control program.The function blocks are generally created in thestandardized programming language of "Struc-tured Text" (ST) as per IEC 61131-3. A Proxy FBpresents access to its functions in encapsulatedgraphic form and can therefore also be called bythe "simpler" programming languages of IEC61131-3, such as LD/COP (Ladder Diagram/ Con-tact Plan), FBD/FUP (Function Block Diagram/

Function Plan) or IL/APL (Instruction List/ Applica-tion List).

Proxy FBs are generally specified by device pro-file working groups and provided to the user indifferent ways, depending on the business modelThe advantage here is that they can be used incontrollers from different manufacturers. Individualdevice manufacturers can also make use of thisto give their "slaves" competitive advantages by

encapsulating certain functions.

For the practical use of FBs by application pro-grammers, an i nterface that is system-neutralfrom the viewpoint of the many controller manu-facturers (Application Programmer's Interface orAPI) must be defined in addition to the knownPROFIBUS communication interface (communi-cation platform, MS0, MS1, MS2, Figure 11) spec-ified in IEC 61158. This makes it easy to port usersoftware and the proxy FBs used from the pro-grammable logic controller (PLC) of manufacturerA to the PLC of manufacturer B using standard-ized communication blocks ("Comm FBs") if the

controller manufacturer offers Comm FBs in theirprogramming library.

3.6 Comm FBs as a system-neutral interface withPROFIBUS

The PNO has defined function blocks (shown inyellow in Figure 11) for the system-neutral inter-faces in the "Communication and Proxy FunctionBlocks according to IEC 61138-3" guideline. The-se function blocks are supported by the lan-guages of IEC 61131-3 and the communicationservices of IEC 61158 defined for PROFIBUS.

The guideline defines communication blocks formaster classes 1 and 2 and slaves and severaladditional help functions as well. The technologi-cal functions of a f ield device can be addresseduniformly using these Comm FBs. All FBs share acommon concept for displaying errors with codingas per IEC 61158-6.

PLC manufacturers offer such standard commu-

nication blocks in PLC-specific "IEC libraries".

Figure 11: The use of functi on blocks (Proxy FB andComm FB)

PROFIBUS DP

MS0 (Cy cl ic ) MS1 (A cy cl ic )

PROFIBUS DP

MS2 (Acyclic) Communications

Platform

(IEC 61158)

Process

ImageComm-FB

IEC 61131-3Field-Device-

Technology (FDT)

Appl icati on

Programmer's

Interface (API)

User-

Program

Device Type

Manager (DTM)

PROFIBUS DP

MS2MS1MS0Communications

Platform (IEC 61158)

Proxy-FB

IEC 61131-3

Device technology

PLC (SPS) Engineering tool

Field device

Master Class 1 Master Class 2

Slave

PROFIBUS DP

MS0 (Cy cl ic ) MS1 (A cy cl ic )

PROFIBUS DP

MS2 (Acyclic) Communications

Platform

(IEC 61158)

Process

ImageComm-FB

IEC 61131-3Field-Device-

Technology (FDT)

Appl icati on

Programmer's

Interface (API)

User-

Program

Device Type

Manager (DTM)

PROFIBUS DP

MS2MS1MS0Communications

Platform (IEC 61158)

Proxy-FB

IEC 61131-3

Device technology

PLC (SPS) Engineering tool

Field device

Master Class 1 Master Class 2

Slave

Foods are bound by especially stringentspecifications for quality and traceability ofthe manufacturing process, including thecommunication technology. With PROFI-BUS, these features are of the highest pri-ority, which is evidenced by its wide distri-bution in the food industry.



In addition to the previously mentioned "neutral-ized" access to acyclical communication functionsvia MS1, the FDT interface (see page 17) com-pletes the Application Programmer's Interface (viaMS2) for the access of engineering and configura-tion tools.

4. Application profiles

To ensure smooth interaction between the busnodes of an automation solution, the basicfunctions and services of the nodes must match.They have to "speak the same language" and usethe same concepts and data formats. This appliesboth for communication and for device functionsand industry sector solutions. This uniformity isachieved through the use of "profiles" relating todevice families or special industry sectorsolutions. These profiles specify features which

"profile devices" must exhibit as a m andatoryrequirement.

These can be cross-device-class features, suchas safety-relevant behavior (Common ApplicationProfiles) or device-class-specific features (Specif-ic Application Profiles). Here, a differentiation ismade between

Device profiles

for robots, drives, process devices, encoders,pumps etc., for example

Industry profilesfor laboratory technology and rail vehicles, forexample

Integration profilesfor the integration of subsystems such asHART or IO-link systems

Figure 1 shows the classification of profiles in thePROFIBUS system building blocks, and Table 5provides an overview of currently available PRO-FIBUS profiles. The following contains furtherinformation on several of them.

Table 5: PROFIBUS application profiles

Profile Name Profile Content PNO Guideline

Specific application profiles

Dosing / Weighing Profile describes the use of dosing and weighing systems on PROFIBUS 3.182a; 3.182 b

EncoderProfile describes the connection of rotary, angular, and linear encoders

with single-turn and multi-turn resolution3.062

Fluid PowerProfile describes the control of hydraulic drives via PROFIBUS

(cooperation with VDMA)3.112

HART on PROFIBUS Prof ile def ines the integrat ion of HART devices in PROFIBUS systems 3.102

Ident SystemsProfile describes the communication between identification devices

(barcode reader, transponder)3.142

LabDevicesProfile specifies the properties of laboratory automation devices on

PROFIBUS2.412

Liquid PumpsProfile defines the use of liquid pumps on PROFIBUS (cooperation with

VDMA)2.422

Low Voltage SwitchgearProfile defines data exchange for low-voltage switchgear (switch

disconnector, motor starter, etc.) on PROFIBUS3.122

PA DevicesProfile specifies the properties of process automation devices on

PROFIBUS3.042

PROFIdriveProfile describes the device behavior and access behavior to data for

variable speed electric drives on PROFIBUS 3.172; 3.272

Remote I/OProfile defines the interchangeability of remote I/O devices in process

automation3.132

SEMIProfile describes properties of semiconductor manufacturing devices on

PROFIBUS (SEMI standard)3.152

General application profiles

Identification & MaintenanceProfile specifies a concept for identification of PROFIBUS devices and

Internet access to device-specific information3.502

iPar-ServerProfile defines the saving of additional i-parameters in the controller and

the read-back of i-parameters after a device replacement3.532

PROFIsafeProfile defines safe communication of safety-related devices (emergency

OFF switch, light array, etc.) with safety controllers via PROFIBUS3.092

Redundancy Profile specifies the mechanism for field devices with redundantcommunication behavior 2.212

Time StampProfile defines the precisely timed assignment of certain events and

actions by time stamping3.522



4.1 PROFIdrive

The PROFIdrive profile is used in production au-tomation. It defines the device behavior, the ac-cess method and the data formats for the drivedata of electrical drives on PROFIBUS, from sim-ple frequency converters to highly dynamic servocontrollers. All the details on this can be found inthe relevant system description (Order No. 4.322).

4.2 PROFIBUS PA (PA devices,"PA profile")

The PROFIBUS PA profile is the basis for usingPROFIBUS in process automation. In addition tothis profile, this application is characterized by

frequently intrinsically-safe operation and devicepower supply via the bus cable. The PA profiledefines the functions and parameters for process-control devices, such as transmitters, actuators,valves and analyzers. These functions and pa-rameters are used to adapt the devices to therespective application and process conditions.The specifications are based on function blocks,and the parameters are classified as input, outputand internal parameters. The profile also specifieshow the various services of the PROFIBUS com-munication protocol are used. Accordingly, forexample, process data exchanged cyclically isbased on a standard format for all devices. In

addition to the measured value and/or manipulat-ed measurement value, this format alsofeatures a status providing information about the

quality of the value and possible limit violations. Itthereby provides the foundation for harmonizedapplications, simplified engineering, deviceexchangeability and increased reliability bymeans of standardized diagnostic information.PA profile version 3.02 has been expanded with ahost of application-oriented functions since the

previous version of 3.01. These functions takeinto account the years of operating experience inPROFIBUS PA systems and implements theresulting user demands.

4.3 Improvements in PA-Prof ileV3.02

The improvements made to PA profile 3.02concentrate on the optimization of lifecyclemanagement of the devices with the goal of link-ing the simplicity of traditional 4 - 20 mA technol-ogy with the performance potential of fieldbustechnology.

Version f lexibility when replacing devices

Up until now, it was necessary to fall back ondevices of the same generation as the installeddevices when devices had to be replaced, eventhough a more state-of-the-art version with addi-tional innovative features was available on themarket. Version 3.02 of the profile does away withthis limitation by enabling (new) devices to auto-matically adjust themselves to the version andfunctions of its predecessor device (Automatic IDNumber Adaption, Figure 12). Here, the (new)device is notified of the version of the predeces-sor device from the controller or control system

and automatically adapts itself to that device'sfunctions without interrupting the process. Thisdevice feature is part of the certification testing ofdevices with profile version 3.02. The next timethe system is planned to stop, the new device canbe integrated into the control system and the newfunctions can be used.

Simplified device integration

In contrast to the trusted configuration of 4 - 20mA devices in the field, the integration of fieldbusdevices puts greater demands on the operator

Figure 12: Device replacement with transfer o f thepredecessors' functions

Humidity measurement plays an importantrole in the processes of almost all indus-tries, but it's integration into fieldbus tech-nology remained disregarded for a longtime. PROFIBUS provided the solution.One example is the humidity measurementcarried out when producing pasta.



due to the larger function scope. Working with thedevice descriptions required for this must be pos-sible for the user without special knowledge,however.

The simplification implemented in profile 3.02 isbased on c ross-manufacturer rules for ensuring

unambiguous compatibility between the descrip-tion files (GSD, EDD, DTM) and the field devices.Among other things, the rules stipulate thestorage of standardized parameters in the deviceand device description, which enables the integra-tion tools to automatically assign devices anddescription files (Figure 13). This meansconsiderable simplification during the initialinstallation or device replacement. In addition,simple and clean labeling on the device housingmakes unambiguous assignment of devices todescription files easier, e.g. when removingdevices from storage. These device features arepart of the certification testing.

Accelerating data uploads and downloads

Depending on the phaseof the life cycle of a sys-tem, considerable amounts of data must betransmitted when adapting parameters, duringcommissioning and during maintenance or device

replacement. Depending on the function scope ofthe devices, this could be several hundredparameters, which makes the time required fortransmission more important. Profile 3.02 optimiz-es transmission through optimum grouping of theparameters and simplified access. Depending onthe amount of data being transmitted, the timerequired could be reduced by a factor of 10.

Continuously standardized device diagnostics

Consistency in device replacement is alsoensured with regard to the output of diagnosticinformation. Devices with profile 3.02 are requiredto output diagnostic information as per the cate-

gories of NAMUR recommendation 107 (Figure14), whereby the mapping is already carried outby the manufacturer. When replacing devices, the

owner therefore need not spend time or effort onany adaptations or changes. All devices provideidentically-structured diagnostic information bydefault, thereby ensuring a quick and easy over-view of the system. Additional detailed informationenables device replacement and repair to beplanned, system downtimes to be avoided, which

saves money, and the service life of the system tobe increased.

4.4 HART on PROFIBUS

In view of the very large number of HART devicesinstalled in the field, their integration into existingor new PROFIBUS systems is a pressing task formost users. The PROFIBUS Profile HART doc-ument (Order No. 3.102) offers an open solutionfor this. It defines the use of the PROFIBUScommunication mechanism without changes tothe protocol and services of PROFIBUS.The document defines a pr ofile of PROFIBUS,which is implemented in the master and slaveabove level 7 and therefore enables the mappingof the client-master server model of HART onPROFIBUS. Full compatibility with HART specifi-cations has been assured by collaborating withthe HART Foundation in drafting the specification.

The HART client application is integrated in aPROFIBUS master and the HART master in a

PROFIBUS slave (Figure 15), whereby the latterserves as a multiplexer and takes over communi-cation with the HART devices.

Figure 13: Unambiguous assignment of devices anddescription files

Figure 14: Diagnostic mapping as per NAMUR recommendation 107

Figure 15: Operating HART devices on PROFIBUS

HART clientapplication

HARTmaster

HART

server

PROFIBUS DP

PROFIBUS Master PROFIBUS Slave HART Device

HART

communication

HART profile

7

1

2

HART profile

7

1

2

HART

comm

HART

comm


HARTmaster

HART

server

PROFIBUS DP


HART

communication

HART profile

7

1

2

HART profile

7

1

2

HART

comm

HART

comm


HARTmaster

HART

server

PROFIBUS DP


HART

communication

HART profile

7

1

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HART profile

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comm

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comm



A communication channel which works inde-pendently of the MS1 and MS2 connections hasbeen defined for the transmission of HART mes-sages. One HMD (HART Master Device) cansupport a number of clients. The number dependson the implementation.

Version 2.0 of the profile extends the existing in-tegration to include standardized PROFIBUSmodules for hard-wired HART devices as well asfor the new WirelessHART device generation.As a r esult, there is no ne ed to implement aprofile layer in the DP master for cyclic dataexchange with DP and channel-specific diagnos-tics.

HART devices can be connected to the HMD viavarious components or to PROFIBUS via mod-ules. These originate from a GSD of the compo-nent or are created with a device-specific moduleconfigurator. This is typically implemented as aclass 2 DP master and as an HMD; furthermore, itcan offer the detailed configuration of complexHART devices using an E DD or the FDT/DTMconcept.

4.5 PROFIsafe

The risk of human injury, damage to productionsystems and environmental harm is inherent inmany industrial processes. This realizationresulted in "safety-related automation technology"becoming of great importance, as its safetyrequirements are far above and beyond those ofstandard automation technology. This demandmust also be satisfied by the fieldbus technology,and the PROFIsafe communication profile servesthis purpose for PROFIBUS.

All the details on this can be found in the relevantsystem description (Order No. 4.341).

4.6 Identification & Maintenance(I&M)

The definitions collected in the Identification &Maintenance (I&M) application profile are bindingspecifications for the storage of specific data ineach PROFIBUS device. This gives the ownerstandard access to all device data through alldevices during configuration and c ommissioningas well during parameterization and updateprocedures. The database for this are XML filesstored on t he www.profibus.com server. Thesefiles are managed online by the device manufacturers and are therefore kept up-to-date overthe entire device life cycle (Figure 16). Using anengineering tool, this data can be read out at anytime, whereby the "device-local" data is comparedto the centralized, daily-updated information fromthe manufacturer for the device in question. Thisis very helpful for system documentation, orderprocesses and maintenance processes, for

example.

5. Device integration

A particular advantage of PROFIBUS is open-ness, which in turn brings with it compatibility witha large number of device and system manufac-turers. However, this does mean that the benefit

of numerous different device and systems suppli-ers is countered by a correspondingly highnumber of different possible HMIs. Standards forthe centralized and uniform integration offieldbuses into automation systems have beendeveloped in order to ensure that a disproportion-ate amount of time and effort is not required withregard to installation, version management anddevice operation. Devices are usually integratedby means of mapping their functionality to opera-tor software. The process is optimized by con-sistent data management throughout the life cycleof the system, with identical data structures for alldevices. All standards cited in the following canbe used in conjunction with PROFIBUS.

Figure 16: The principle of I&M functi ons

EngineeringTool (MS2)

MANUFACTURER_ID=42

PROFILE_ID=F600

ORDER_ID=6ES7 141-1BF00-0XB0

PROFIBUSWeb Server

PROFIBUSDevice

PROFIBUS

ManufacturerWeb Server

I

D

Company Cust.

42 Siemens 0911-8...

Web

www.siem...

42Service

http://.../

EngineeringTool (MS2)

MANUFACTURER_ID=42

PROFILE_ID=F600

ORDER_ID=6ES7 141-1BF00-0XB0

PROFIBUSWeb Server

PROFIBUSDevice

PROFIBUS

ManufacturerWeb Server

I

D

Company Cust.

42 Siemens 0911-8...

Web

www.siem...

42Service

http://.../

The use o f PROFIBUS with the PROFIdriveprofile is widespread in the control ofpackaging machines. All functions are ex-ecuted on a single bus, which considerablyreduces the expenditure for engineering,hardware and t raining.
http://www.profibus.com/http://www.profibus.com/



A summarized representation of device inte-gration can be found in Figure 17.

General Station Descript ion (GSD)

The GSD is provided by the device manufacturerand is the electronic data sheet for the communi-cation properties of each and every PROFIBUSdevice. It supplies all information necessary forcyclical communication with the PROFIBUS mas-ter and f or the configuration of the PROFIBUSnetwork in the form of a text-based description. It

contains the key data of the device, informationabout its communication capabilities and infor-mation about, e.g. diagnostic values. The GSDalone is sufficient for the cyclic exchange ofmeasured values and manipulated variables be-tween field device and automation system.

Electronic Device Description (EDD)

The GSD alone is not sufficient to describe theapplication-specific functions and parameters ofcomplex field devices. A powerful language isrequired for the parameterization, service,

maintenance and diagnostics of devices from theengineering system. The Electronic DeviceDescription Language (EDDL) standardized inIEC 61804-2 is available for this purpose. Furtherdevelopment is promoted jointly by PI, the HARTCommunication Foundation, the Fieldbus Foun-dation and the OPC Foundation.

An EDD is a text-based device description whichis independent of the engineering system's OS. Itprovides a description of the device functionscommunicated acyclically, including graphicsbased options, and also provides device infor-mation such as order data, materials, mainte-nance instructions etc.

The EDD provides the basis for processing anddisplaying device data on the EDD Interpreter.

The EDD Interpreter is the open interfacebetween the EDDs and the operator program. Itprovides the operator program with data forvisualization with a standard look & feel, regard-less of the device and manufacturer.

Device Type Manager (DTM) and Field Device

Tool (FDT) interface

In comparison to the GSD and EDD technologiesbased on descriptions, the FDT/DTM technologyuses a software-based method of device integra-tion. The DTM is a s oftware component andcommunicates with the engineering system viathe FDT interface. The FDT/DTM technology isbeing developed further by the FDT Group.

A DTM is a device operator program by means ofwhich device functionality (device DTM) or com-munication capabilities (communication DTM) aremade operational; it features the standardizedFDT (Field Device Tool) interface with a f rame

application in the engineering system. The DTM isprogrammed on a dev ice-specific basis by themanufacturer and contains a separate user inter-face for each device. DTM technology is veryflexible in terms of how it is configured.

The FDT interface is a cross-manufacturer openinterface specification which supports the integra-tion of field devices into operator programs usingDTMs. It defines how DTMs interact with an FDTframe application in the operator tool or engineer-ing system. The interface itself is independent ofthe communication protocol and i s available atpresent for more than 13 protocols includingPROFIBUS, PROFINET and IO-Link.

Tool Calling Interface (TCI)

The requirement for centralized operability ofcommunication-capable sensors and actuators ofa production system from the engineering stationof the automation system led to the developmentof TCI. TCI is an open i nterface between theengineering tool of the overall system and thedevice tools of complex devices, e.g. with drivesor laser scanners, which enable centralized pa-rameterization and diagnostics from theengineering station during operation. TCI isnon-manufacturer-specific and allows dynamicparameters to be l oaded to devices withouthaving to exit the automation-system engineeringtool. For users, this means a considerable simpli-fication and time savings when calling up devicetools and when carrying out configuration andonline diagnostics of the systems and machines.In additional to directly-integrated device tools,technologies such as EDDL and FDT can be usedvia corresponding application software.

Figure 17: Technologies for device integration

GSD DTMEDD

Description of device functionalities

Interpreter

GSD / EDD

Frame Applic.

DTM

Control / Engineering system

Text Text Software

Device Tool

Software

Interface

TCI

Integration of device functionalities

Field device

User

Manufacturer

GSD DTMEDD

Description of device functionalities

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Frame Applic.

DTM

Control / Engineering system

Text Text Software

Device Tool

Software

Interface

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Integration of device functionalities

Field device

User

Manufacturer



6. Quality assurance andcertification

For PROFIBUS devices of different types andmanufacturers to be abl e to perform differenttasks in the automation process correctly, theymust exchange information over the bus withouterrors. A prerequisite for this is a standard-compliant implementation of the communicationprotocols and application profiles by the devicemanufacturer. To ensure that this demand is met,the PI established a quality-assurance procedurewhere certificates are granted for test-passingdevices using test reports as a basis (Figure 18).

The aim of certification is to provide users with theassurance that PROFIBUS field devices fromdifferent manufacturers are capable of error-freeoperation when used together. For this purpose,the field devices are tested in practical applica-tions in accredited independent test laboratorieswith the required testing accuracy as per thequality guidelines of PI. This makes it possible toidentify any misinterpretation of the standards atan early stage so that manufacturers can take thenecessary remedial action before devices areimplemented in the field. The test also examinesthe field devices compatibility with other certifiedfield devices. Once the tests have been passedsuccessfully, a device certificate is issued by PI'scertification center upon application by the manu-facturer.

The test procedures and certification process aredescribed in the respective guidelines.

The test procedure

The prerequisites for testing are an i ssued ID

number and a GSD file. An EDD for the field de-vice or the field device itself may also be required.

The test procedure, which is the same for all testlaboratories, is comprised of several steps:

A GSD/EDD check ensures that the devicedescription files comply with the specifications.

During the hardware test, the electricalproperties of the PROFIBUS interface on the

test subject are tested for compliance with thespecifications. This includes, for example, theterminating resistors, the suitability of drivermodules and other modules used and thequality of t

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