Endress+Hauser Profibus Planing Guide

BA 034S/04/en/06.04 Nr. 56004242

PROFIBUS DP/PA

Field Communication

Table of Contents

Revision History . . . 3

Registered Trademarks . . . 3

1

Safety

5

1.1 General . . . 5

1.2 Conventions and icons . . . 6

1.3 Documentation . . . 7

2

Introduction to PROFIBUS

8

2.2.2 PROFIBUS DP communication protocol . . . 16

2.2.3 Application profiles . . . 19 2.2.4 PROFIsafe . . . 19 2.2.5 PROFIdrive . . . 20 2.2.6 Integration technologies . . . 21 2.2.7 Quality assurance . . . 21 2.3 PROFIBUS PA . . . 22 2.3.1 Operating principle . . . 24

2.3.2 Applications in hazardous areas . . . 25

2.4 Field Device Tool (FDT) . . . 26

3

PROFIBUS DP basics

29

3.1 Synopsis . . . 29

3.2 Topology . . . 31

3.3 Bus access method . . . 34

3.4 Network configuration . . . 35

3.5 Applications in hazardous areas . . . 36

4

PROFIBUS PA Basics

38

4.1 Synopsis . . . 38

4.2 Segment coupler and links . . . 39

4.2.1 Segment coupler . . . 40

4.2.2 Link . . . 40

4.3 Topology . . . 41

4.4 Bus access method . . . 44

4.4.1 Segment coupler . . . 44

4.4.2 Gateway-type segment coupler . . . 45

4.4.3 Links . . . 46

4.5 Network Configuration . . . 47

4.6 FISCO . . . 48

4.7 Fieldbus multi-drop barriers . . . 49

5

PROFIBUS PA Planning

50

5.1 Selection of the segment coupler . . . 50

5.2 Cable type and length . . . 51

5.3 Current consumption . . . 52

5.4 Voltage at last device . . . 54

5.4.1 Worst case calculation . . . 54

5.4.2 Accurate calculation . . . 55

5.5 Calculation examples for bus design . . . 56

5.5.1 Example 1: Non-hazardous application . . . 56

5.5.2 Example 2: EEx ia application . . . 58

5.5.3 Example 3: EEx ib application . . . 60

5.5.4 Example: fieldbus barrier application . . . 63

5.6 Data quantity . . . 64

5.7 Addressing and cycle times . . . 68

5.7.1 Addressing . . . 68

5.7.2 Cycle times . . . 68

5.7.3 Example 1: Siemens segment coupler . . . 69

5.7.4 Example 2: Pepperl+Fuchs SK1 coupler . . . 70

5.7.5 Example 3: Pepperl+Fuchs SK2 coupler . . . 71

5.7.6 Example 4: Siemens PA link . . . 73

6

Installation PROFIBUS PA

74

6.1 Cabling . . . 74

6.2 Grounding and shielding . . . 75

6.3 Termination . . . 79

6.4 Overvoltage protection . . . 79

6.5 Installation of the devices . . . 80

6.6 Setting addresses . . . 82

6.6.1 Using DIP switches . . . 82

6.6.2 Software addressing with FieldCare . . . 83

6.6.3 Software addressing with Commuwin II . . . 84

7

System Integration

85

7.1 Network configuration . . . 85

7.1.1 Tested systems . . . 86

7.2 Device database files (GSDs) . . . 87

7.2.1 GSD file example . . . 89

7.2.2 Full configuration with manufacturer-specific GSDs . . . 90

7.2.3 Partial configuration with manufacturer-specific GSDs . . . 92

7.2.4 Profile GSD . . . 93

7.3 Cyclic data exchange . . . 94

7.3.1 Status codes: Device status BAD . . . 95

7.3.2 Status code: Device status UNCERTAIN . . . 96

7.3.3 Status codes: Device status GOOD . . . 97

7.4 Bus parameters . . . 99

7.4.1 Aligning FieldCare . . . 100

7.4.2 Aligning Commuwin II . . . 100

7.4.3 Commissioning the Pepperl+Fuchs SK2 . . 101

8

Device Parametrization

104

8.1 PROFIBUS PA block model . . . 105

8.2 PROFIBUS PA profile . . . 106

8.2.1 Block structure . . . 108

8.2.2 Device management . . . 109

8.2.3 Transmitter and actuator blocks . . . 110

8.2.4 Analysis devices . . . 113

8.2.5 Function overview . . . 114

8.3 FieldCare Asset Management . . . 116

8.3.1 Using FieldCare . . . 117

8.3.2 Generation of a live list . . . 118

8.3.3 Device parametrization . . . 118

8.3.4 On-line parametrization . . . 119

8.3.5 Plant View . . . 119

8.4 Commuwin II Operating Program . . . 120

8.4.1 Operation . . . 120 8.4.2 Device menu . . . 121

9

Trouble-Shooting

122

10

Technical Data

125

11

PROFIBUS Components

127

11.1 Endress+Hauser field devices PROFIBUS PA . . . . 127

11.2 Endress+Hauser field devices PROFIBUS DP . . . . 153

11.3 Network components . . . 160

11.4 Asset management and operating software . . . 162

11.5 Supplementary documentation . . . 163

12

Terms and Definitions

164

12.1 Bus architecture . . . 164

12.2 Components . . . 165

12.3 Data exchange . . . 166

12.4 Miscellaneous terms . . . 167

13

Appendix: Calculation Sheets

168

13.1 Explosion hazardous areas EEx ia . . . 168

13.2 Explosion hazardous areas EEx ib . . . 170

Revision History

Registered Trademarks

• PROFIBUS®

is a registered trademark of PROFIBUS User-Organisation e.V., Karlsruhe, Germany • Microsoft®, Windows®, Windows NT®, Windows 2000®,Windows XP®

are registered trademarks of Microsoft Corporation, Redmond, Washington, USA

Issue Changes BA198F/00/en/11.99 Original Version

BA034S/04/en/07.04 Revision of manual to include latest information on PROFIBUS standard Additional descriptions of new components

1

Safety

1.1

General

Approved usage These guidelines have been written with the view of giving the potential PROFIBUS user an introduction to the planning and commissioning of a PROFIBUS PA network. They are based on the experience of Endress+Hauser employees who have been actively involved in PROFIBUS projects and who, in the meantime, have successfully commissioned a large number of plants.

The approved usage of the individual devices that are used in a network can be taken from the corresponding device operating instructions.

Installation,

commissioning, operation

The field devices, segment coupler, cables and other components must be designed to operate safely in accordance with current technical safety and EU standards. If installed incorrectly or used for applications for which they are not intended, it is possible that dangers may arise. For this reason, the system must be installed, connected, operated and maintained according to the instructions in this and other relevant manuals: personnel must be authorised and suitably qualified.

Explosion hazardous area If the system is to be installed in an explosion hazardous area: • Ensure that all personnel are suitably qualified

• Observe the specifications in the certificate • Observe any national and local regulations.

For PROFIBUS PA, it is recommended components should be designed in accordance with the FISCO model. This greatly simplifies the acceptance testing of the PROFIBUS PA segment. Where another scheme is used, e.g. Exe/Exi multibarriers, proof of intrinsic safety must be furnished.

1.2

Conventions and icons

In order to highlight safety relevant or alternative operating procedures in the manual, the following conventions have been used, each indicated by a corresponding icon in the margin.

Safety conventions .

Explosion protection .

Electrical symbols .

Icon Meaning

A note highlights actions or procedures which, if not performed correctly, may indirectly affect operation or may lead to an instrument response which is not planned

Caution!

Caution highlights actions or procedures which, if not performed correctly, may lead to personal injury or incorrect functioning of the instrument

Warning!

A warning highlights actions or procedures which, if not performed correctly, will lead to personal injury, a safety hazard or destruction of the instrument

Icon Meaning

Device certified for use in explosion hazardous area

If the device has this symbol embossed on its name plate it can be installed in an explosion hazardous area in accordance with the specifications in the certificate or in a safe area

Explosion hazardous area

Symbol used in drawings to indicate explosion hazardous areas. Devices located in and wiring entering areas with the designation “explosion hazardous areas” must conform with the stated type of protection

Safe area (non-explosion hazardous area)

Symbol used in drawings to indicate, if necessary, non-explosion hazardous areas. Devices located in safe areas stiill require a certificate if their outputs run into explosion hazardous areas.

Icon Meaning Direct voltage

A terminal to which or from which a direct current or voltage may be applied or supplied

Alternating voltage

A terminal to which or from which an alternating (sine-wave) current or voltage may be applied or supplied

Grounded terminal

A grounded terminal, which as far as the operator is concerned, is already grounded by means of an earth grounding system

Protective grounding (earth) terminal

A terminal which must be connected to earth ground prior to making any other connection to the equipment

Equipotential connection (earth bonding)

A connection made to the plant grounding system which may be of type e.g. neutral star or equipotential line according to national or company practice

1.3

Documentation

The guidelines are structured as follows:

Chapter Title Content

Chapter 1 Introduction Advantages of a bus as well as general information about the PROFIBUS standard

Chapter 2 Introduction PROFIBUS An overview of PROFIBUS standards for factory and process automation

Chapter 3 PROFIBUS DP Basics Information about PROFIBUS DP

Chapter 4 PROFIBUS PA Basics Information about PROFIBUS PA, couplers, links and use in explosion hazardous areas (FISCO-Model)

Chapter 5 PROFIBUS PA Planning What must be observed when planning PROFIBUS DP/PA systems, with examples

Chapter 6 PROFIBUS PA Installation Notes on the installation of devices in a PROFIBUS DP/PA system

Chapter 7 System Integration Notes on mapping PROFIBUS PA devices in a PLC Chapter 8 Device Configuration General information on setting the parameters in

Endress+Hauser devices PROFIBUS applications

Chapter 9 Trouble-Shooting Causes and remedies for general faults that may occur during the commissioning of a system

Chapter 10 Technical Data Principle technical data of PROFIBUS PA and PROFIBUS DP Chapter 11 PROFIBUS Components Profiles of the Endress+Hauser PROFIBUS DP and PROFIBUS

PA devices

Chapter 12 Terms and Definitions Explanation of the terminology used to describe bussystems Chapter 13 Appendix Calculation sheets for your applications

2

Introduction to PROFIBUS

PROFIBUS is a standardized, open communications system for all areas of application in factory and process automation. The technology was introduced in the early 1990s and has been developed continuously ever since. The PROFIBUS DP and PROFIBUS PA technologies are specified in the international standards EN 50170 and IEC 61158 and are suitable for replacement of discrete and analog signals in control systems.

PROFIBUS DP The original specification was aimed primarily at the requirements of Factory Automation, but this was quickly extended to include the requirements of process automation, in particular the need for intrinisically safe bus powering of devices. This is mirrored in the PROFIBUS PA specifications. As its popularity increased, the PROFIBUS DP specifications were extended to include a number of common but optional application profiles for e.g. safety, time stamping etc.. Similarly several application profiles were developed to meet the needs of specific device types, e.g. measuring devices, drives, remote I/O etc..

By the turn of the century, the PROFIBUS DP/PROFIBUS PA standard had covered many of the requirements of both Factory and Process Automation from field to control level - as shown by Fig. 2-1. It was rewarded by a large degree of support from both equipment manufactures and users, and today has an installed base of over 10,000,000 I/0 points.

Fig. 2-1: Overview of PROFIBUS technologies

PROFINET At this point in time, however, Ethernet had already begun to work its way down from the office environment on to the factory floor, and was being seen as the future standard for control system backbones. Office Ethernet is in itself not suitable for control systems, since media access is stochchastic (CSMA/CD), not deterministic, so there was a need to develop a further standard for the operations level. The result is the PROFINET specification, which not only addresses the problems of deterministic control for real time and isochronic real time applications, but also those of network engineering, operation and I/O integration of control and fieldbus networks. PROFINET is only just at the beginning of its development, but promises many exciting solutions for the future. PROFIBUS User

Organisations

PROFIBUS is supported by PROFIBUS International, which is a world-wide association of PROFIBUS user organisations. It is responsible for the development of the standard, its maintenance, the conformance testing of PROFIBUS devices as well as the issuing of device certificates. It has a number of independent accredited PROFIBUS Competence Centers thoughout the world (one is located Endress+Hauser Process Solutions AG) which maintain test facilities that

MBP (IEC 61158-2) PLC IPC 12:0014:0016:0018:00 20:0022:00 Internet OS ES RS-485/FO Ethernet TCP/IP HART, ASi OPERATIONS: PROFINET

2.1

PROFINET

As can be seen from Fig. 2-1, PROFINET is the Ethernet-based automation standard of PROFIBUS International. It intended for use in a wide range of industrial applications, for example in:

• Production systems • Assembly systems

• Systems in the automotive industries • Systems in the food and beverage industries • Packaging systems

PROFINET allows the implementation of distributed automation structures, integration of simple decentralized field devices as well as the operation of motion control applications. As can be seen in Fig. 2-2, each of these applications places different demands on the system with regard to response times and real time operation.

Fig. 2-2: PROFINET allows the parallel operation of several "Control Islands" via Ethernet TCP/IP

PROFINET recognises this fact and provides a modular solution which treats each application as a separate "Control Island". Such islands might be for example, a SCADA system for monitoring and operating the plant, a control network for flow, ratio and level control of a reactor, a complete filling machine or an industrial robot. PROFINET specifies those functions that allow implementation of an integrated automation solution from network installation to web-based diagnosis. The modular structure of PROFINET permits extremely easy expansion. PROFINET operates over a high speed (100 Mbit/s) switched Ethernet TCP/IP backbone. This ensures:

• Full duplex communication • Isochronous communication

• Priorization of Real-Time Frames (Quality of Service)

A specially developed PROFINET chip enables switch integration into a device and controller. The specification itself has two facets:

• PROFINET CbA (Component-based Automation)

• PROFINET I/O (Integration of PROFIBUS devices in PROFINET) These are discussed in more detail in the following sections

Internet

Controller and HMI Field Devices Motion Control

TCP/IP Real Time Isochronic Real Time

100ms 10ms <1ms

2.1.1

Component-based Automation

Component-based Automation is best explained by taking the practical example that PROFIBUS International uses in its own presentations, that of bottling in brewing or soft drinks production. The bottling is done by a number of machines that wash, fill, close and pack the bottles. Prior to this the product must be manufactured, a classical process control application. Fig. 2-3 illustrates the task in question.

Fig. 2-3: Schematic diagram of automation tasks in a brewery or soft drinks plant

Network architecture The network architecture depends on the nature of the processes involved and the demands they make on control. Typically, however, the closing and packing of bottles are purely factory automation tasks requiring isochronous real time communication, washing and filling are hybrid tasks and the production of the beer or soft drink is a process automation task. Fig. 2-4 illustrates the type of architecture to be expected, the production process being a PROFIBUS DP/PA task and the washing and filling a typical PROFIBUS DP task today.

Fig. 2-4: Possible plant architecture for brewery or soft drinks plant

Technological module PROFINET considers machines and systems to be divided into technological modules, each of which comprises of mechanical, electrical and software components. The functionality of the technological modules is encapsulated in the form of PROFINET components. These have standard interfaces for use in a PROFINET engineering tool. They can be used as building blocks, combined as required and are easily reused. The PROFINET components for all technological modules in a machine or component assembly are supplied by the manufacturer. on e.g. a CD-ROM.

Production

Pack Close

Wash Fill

Machine 1 Machine 2 Machine 3

Horizontal integration along the production line

Data exchange between intelligent devices within the machine

Pack Close Wash Fill Machine 1 Machine 2 Machine 3 PROXY Mash Ferment Production PROXY Filter ES Engineering

PROFIBUS DP/PA PROFIBUS DP

CbA engineering The technological modules are basically Global Function Blocks for the machine or component assemblies in the plant and can be used within a PROFINET Engineering Tool to build up a logical view of the plant. The standard interfaces allow the logical sequences to be programmed in a graphical environment. Thus for instance, a connection between the "Finished" output of one machine to the "Start" input of another, will cause the appropriate message to be sent over Ethernet and the downstream machine will start up when the upstream machine has finished its task.

Fig. 2-5: Machine and component assembly manufacturer’s deliver standardised function blocks for their equipment

The Engineering Tool is also used to build up a view of the the PROFINET and PROFIBUS network, the technical modules forming the link between the two views. When the tool goes on-line, i.e. the various components are connected physically to the network, the logical project is downloaded to the connected machines and devices. The system can then be started up with preconfigured links.

Fig. 2-6: The links are downloaded to the machines and the system is ready for start-up

Manfacturer A Component

Editor Interface Manufacturer's programming

and configuration tools

Manfacturer B Component Editor Interface Manfacturer C Component Editor Interface PROFInet Configuration Editor Pack Close Wash Fill Machine 1 Machine 2 Machine 3 PROXY Mash Ferment Production PROXY Filter Download

2.1.2

I/O integration

PROFINET I/O devices PROFINET allows direct interfacing of decentralized field devices on Ethernet. This supports flat communication hierarchies in automation. All the devices used are connected in a consistent network structure and therefore provide open communication throughout the entire production system. PROFINET defines three types of I/O device:

• I/O controller, the device containing the control program and managing data exchange to assigned field devices

• I/O device, the field device connected to the I/O controller • I/O supervisor, the HMI and diagnostic station

Fig. 2-7 shows the types of data that are exchanged between the three components.

Fig. 2-7: Data exchange between PROFINET I/O devices

PROFINET communication In order to achieve the very short response times required in motion control a special ASIC chip is available. The communication stack is shown in Fig. 2-8.

I/O Device Field Device I/O Controller e.g. PLC Ethernet I/O Supervisor

e.g. SCADA or Configuration

Diagnostic Status control Parametrization Configuration Production Data Alarms Diagnosis Up/Download

Real Time Switch ASIC

Ethernet _{Real Time}

IRT RT IP TCP UDP IT applications HTPP SMNP DHCP... PROFIBUS applications Standard data Real-time data Real-time

It can be seen that PROFINET uses Ethernet at three performance levels for communcation between I/O devices:

• Engineering and time-uncritical data are transferred via TCP/IP and DCOM. • For time-critical process data, e.g. alarms, a real-time channel is available(RT). It is

implemented as software based on available controllers.

• For motion control isochronous real-time communication (IRT) is available which allows jitter accuracy of 1 µs at a clock rate of 1 ms.

The integration of existing field bus applications is accomplished with the proxy concept. The proxy is the representative of the field bus devices on the PROFINET, see Fig. 2.4.

The network management covers all the functions for the administration of PROFINET devices in Ethernet networks:

• Device and network configuration, e.g. issue of IP parameters based on standards like DHCP; Network diagnosis based on standards like SNMP

• Integration of Web functions, e.g. access to components by means of standard technologies from the Internet field such as HTTP, XML, HTML and addressing with scripting.

Field device integration The signals from the (PROFIBUS DP/PA) field devices (decentralized peripherals) are processed directly in the assigned controller. The controller communicates with other PROFINET I/O devices via a proxy. Devices are integrated in the controller by means of standard GSD files.

Integration of the decentralized field devices is an in the PROFINET system is optional add-on to distributed automation. Here a special GSD file, GSDML written in XML is used for integration. A combination of the standard and top-level integration can be implemented in a PROFINET network at any time.

Installation The specific requirements for Ethernet networks in an industrial environment are: • System-specific cable routing

• Specific degree of networking for each machine/system • Linear network structures

• Rough industry-compatible cables and connectors with special requirements fulfilled in terms of EMC and temperature.

PROFINET installations are based on these principles and provide the device manufacturer with clear specifications for device interfaces and the wiring for them. The PROFINET Installation Guide provides the system manufacturer/operator with simple rules for the installation of Ethernet networks.

2.2

PROFIBUS DP

Fig. 2-9: Overview of PROFIBUS standards

Fig. 2-9 gives an overview of PROFIBUS DP system standards: DP stands for Decentralised Periphery. The standards comprise the following groups:

• Transmission Technology

PROFIBUS signal transmission is based on the RS-485, fibre optics or IEC 61158-2 standards. In the latest literature the latter is also referred to as MBP or MBP-IS (Manchester Bit Protocol). • Communication Technology

The PROFIBUS DP communication protocol is at the core of the standard. It is available in three variants, DP-V0, DP-V1 and DP-V2.

• Common Application Protocols

A set of optional protocols for network management. • Device Application Protocols

A set of protocols for particular device types or applications, e.g. measuring devices or motion control.

• Integration Technology

These standards determines how field devices can be integrated into PROFIBUS systems. • System Profiles

Contain specifications regarding conformance classes, interfaces and constraints.

The standards of interest to process automation are described in the following sections. Table 2.1 gives an overview of where these are used.

Target Application Factory Automation Motion Control Process Automation

Safety

Typical designation PROFIBUS DP PROFIdrive PROFIBUS PA PROFIsafe Application profile None or specific PROFIdrive PA device PROFIsafe Communication PROFIBUS DP protocol PROFIBUS DP protocol PROFIBUS DP protocol PROFIBUS DP protocol Transmission RS-485 RS-485 RS-485 MBP-IS RS-485 MBP-IS

PROFIBUS DP

PROFISAFE, Time Stamp, Redundancy, etc.

RS485: RS485-IS: NRZ Intrinsic Safety Fiber: Optics: MBP *): MBP-LP: MBP-IS: Glass Multi Mode

Glass Single Mode

Manchester Bus Powered Low Power Intrinsic Safety PCF / Plastic Fiber Application Application Communication Transmission Profiles II Profiles I Technologies Technologies PA Devices R IO for P A SEM I PR OFIdri ve In den t Sys tems W eigh ing & Do sin g Encod er In te gr atio n Sy ste m - Descrip ti on ( G S D , EDD) - M ast er C onf or m anc e Cl as se s - T ools (DTM, Co figu rator s) - In terf aces (C omm-FB , F D T, etc.) - Co ns tr ai nt s Te ch no lo gi es Profi les 1.. .x

2.2.1

Transmission standards

PROFIBUS provides for three different transmission technologies, RS-485, Fibre Optics and MBP (Manchester Coding/Bus Powered). Both RS-485 and IEC 61158-2 make provision for intrinsically safe transmission in hazardous areas.

RS-485 RS-485 is used for tasks that require high transmission rates. The transmission technology is simple and cost-effective: no expert knowledge is required for installation of the cable. STP copper cable (shielded, twisted pairs) with one conductor pair is used. RS-485 allows a bus structure to be built that allows addition or removal of stations or the step-by-step commissioning of the system without influencing other stations. Subsequent expansions (within defined limits) have no effect on stations already in operation. The transmission rate can be set between 9.6 Kbit/s and 12 Mbit/s, however, all PROFIBUS DP within a system must operate at the same rate.

Up to 32 stations (master or slaves) can be connected to a single segment. If more than 32 stations are required, repeaters may be used. The maximum permissible line length depends on the transmission rate. Four RS-485 cable types (Types A - D) for designed for different applications are available on the market. PI recommends the use of cable type A.

More details on designing networks are to be found in Chapter 3.

RS-485 IS RS-485 IS is a recent innovation in response to an increasing market demand for the use of RS-485 in explosion-hazardous areas. A corresponding PROFIBUS guideline is now available that specifies the configuration of intrinsically safe RS-485 solutions with simple device interchangeability. It details the current and voltage levels that must be adhered to by all stations in order to ensure safe functioning during interconnection. When active sources are connected, the sum of the currents of all stations must not exceed the maximum permissible current allowed by the circuitry. In contrast to the FISCO model (see below), all stations represent active sources. Up to 32 stations can be connected to the intrinsically safe bus circuit.

MBP IEC-61158-2 physical layer describes several connection technologies. PROFIBUS uses only one: MBP ("Manchester Coding" and "Bus Powered"). To avoid confusion, PROFIBUS International has decided to use MBP in all its literature in future.

MBP is synchronous transmission at a defined transmission rate of 31.25 Kbit/s using Manchester coding. It is used in process automation as it also satisfies the key demands for intrinsic safety and two-wire bus power. MBP transmission technology is usually limited to specific segments within a plant, which are then linked to a RS485 segment via a segment coupler or link, see Chapter 4. Tree or line structures (and any combination of the two) are network topologies supported by PROFIBUS with MBP transmission with up to 32 stations per segment and max. 126 per network.

FISCO Model The FISCO model (Fieldbus Intrinsically Safe Concept) considerably simplifies the planning, installation and expansion of PROFIBUS networks in explosion-hazardous areas. It stipulates that a network is intrinsically safe and requires no individual intrinsic safety calculations provided the four relevant bus components (field devices, cables, segment couplers and bus terminators) fall within predefined voltage, current, output, inductance and capacity limits. The corresponding proof is provided by certification of the components through authorized accreditation agencies, such as PTB and BVS (Germany) or UL and FM(USA). When FISCO-approved devices are used, not only is it possible to operate more devices on a single line, but the devices can also be replaced or the line can be expanded during operation without the need for time-consuming calculations or system certification. MBP with FISCO model is sometimes referred to as MBP-IS.

Fiber optics Fiber optic transmission is used for fieldbus applications that preclude the use of copper wires, e.g. for environments with very high electromagnetic interference or when particularly large distances need to be covered. PROFIBUS guideline (2.021) for fiber optic transmission specifies the technology available for this purpose, including multimode and single mode glass fiber, plastic fiber, and HCS® fiber. When determining these specifications, great care was naturally taken to allow problem-free integration of existing PROFIBUS devices in a fiber optic network without the need to change the protocol behavior of PROFIBUS. This ensures backward compatibility with existing PROFIBUS installations.

2.2.2

PROFIBUS DP communication protocol

PROFIBUS DP is designed for fast data exchange at control and field level. The exchange of data with distributed devices is primarily cyclic and the associated communication functions are specified by the basic PROFIBUS DP protocol (version DP-V0). The special demands of particular applications have meant that the basic functionality has been gradually expanded, so that now three versions are available: DP-V0, DP-V1 and DP-V2. All versions are specified in IEC 61158.

System configuration and device types

DP supports implementation of both mono-master and multi-master systems. This affords a high degree of flexibility during system configuration. A maximum of 126 devices (masters or slaves) can be connected to a bus. In mono-master systems, only one master is active on the bus during operation of the bus system. The device types are as follows:

• DP master class 1 (DPM1) is a central controller that cyclically exchanges information with the distributed stations (slaves) at a specified message cycle. Typical DPM1 devices are

programmable logic controllers (PLCs) or PCs. A DPM1 has active bus access with which it can read measurement data (inputs) of the field devices and write the setpoint values (outputs) of the actuators at fixed times. This continuously repeating cycle is the basis of the automation function.

• DP master class 2 (DPM2) are engineering, configuration or operating devices. They are implemented during commissioning and for maintenance and diagnostics in order to configure connected devices, evaluate measured values and parameters and request the device status. A DPM2 does not have to be permanently connected to the bus system. The DPM2 also has active bus access .

Slaves are peripherals (I/O devices, drives, HMIs, valves, transducers, analyzers) that read in process information and/or use output information to intervene in the process. There are also devices that solely process input information or output information. As far as communication is concerned, slaves are passive devices, they only respond to direct queries. This behavior is simple and cost-effective to implement (in the case of DP-V0 it is already completely included in the hardware).

Figure 2-10 shows the system configuration of a mono-master system. The PLC is the central control component. The slaves are decentrally coupled to the PLC over the transmission medium. This system configuration enables the shortest bus cycle times. In multi-master systems several masters are connected to one bus. They represent either independent subsystems, comprising one DPM1 and its assigned slaves, or additional configuration and diagnostic devices.

Fig. 2-10: Basic principle of Version DP-V0 in mono-master system

Version DP-V0 Version DP-V0 provides the basic functionality for a mono-master architecture with high-speed, deterministic master-slave communication, see Fig. 2-10, including:

• cyclic data exchange

• station, module and channel-specific diagnostics

• four different interrupt types for diagnostics and process interrupts • pulling and plugging of stations.

Controller

Cyclic communication in master-slave relationship

Version DP-V1 Fig. 2-11 shows the standard architecture for PROFIBUS DP, Version DP-V1. This contains enhancements for process automation, in particular acyclic data communication for parameter assignment, operation, visualization and interrupt control of intelligent field devices from a so-called Class 2 master. In addition, it offer three additional interrupt types: status interrupt, update interrupt and a manufacturer-specific interrupt.

Fig. 2-11: Standard architecture for Version DP-V1

Cyclic and acyclic communication

Cyclic data communication between the DPM1 and its assigned slaves is automatically handled by the DPM1 in a defined, recurring sequence. The user defines the assignment of the slave(s) to the DPM1 when configuring the bus system. The user also defines which slaves are to be included/ excluded in the cyclic user data communication. Data communication between the DPM1 and the slaves is divided into parameterization, configuration and data transfer. Before the master includes a DP slave in the data transfer phase, a check is run during the parameterization and configuration phase to ensure the correct configuration.

In addition to the station-related user data communication, which is automatically handled by the DPM1, the master can also send control commands to all slaves or a group of slaves simultaneously. These control commands are transmitted as multicast commands and enable sync and freeze modes for event-controlled synchronization of the slaves.

For safety reasons, it is necessary to ensure that DP has effective protective functions against incorrect parameterization or failure of transmission equipment. For this purpose the DP master and the slaves are fitted with monitoring mechanisms in the form of time monitors. The monitoring interval is defined during configuration.

Acyclic data communication is the key feature of version DP-V1. This forms the requirement for parameterization and calibration of the field devices over the bus during runtime and for the introduction of confirmed alarm messages. Transmission of acyclic data is executed parallel to cyclic data communication, but with lower priority.

Addressing with slot and index is used both for cyclic and acyclic communication services. When addressing data, PROFIBUS assumes that the physical structure of the slaves is modular or can be structured internally in logical functional units, so-called modules. The slot number addresses the module and the index addresses the data blocks assigned to a module. Compact devices are regarded as a unit of virtual modules. These can also be addressed with slot number and index.

Class 1 master Controller Cyclic communication in master-slave relationship PROFIBUS DP Order Code XXXXXXXXXXXXXXXXXX Ser.-No. XX X XXXX Mat. 1.4571 / Al3 O2 / FPM IP 65 P -1 ... 2 bar U 10,5 ... 45 V DC P 20 bar4...20 mA Int ensor P Span 100 mbarminmax Patented Acyclic communication in master-slave relationship Class 2 master e.g. Parametrization Medium access by token passing PROFIBUS PA Coupler

Version DP-V2 Version DP-V2 contains further enhancements to DP-V1 and is geared towards the demands of drive technology. Due to additional functionalities, such as isochronous slave mode and lateral slave communication (DXB) etc., DP-V2 can also be implemented as a drive bus for controlling fast movement sequences in drive axes.

Fig. 2-12: Slave-to-slave communication with Version DP-V2

The enhancements are as follows:

• Slave-to-Slave Communication enables direct, time-saving, communication between slaves without the detour over a master. Figure 2-12 shows the mechanism. On the command of the master, one slave acts as "publisher" and broadcasts its information to other slaves embedded in the sequence, the so-called "subscribers". This enables slaves to sense data from other slaves and use them as their own input. This not only opens up a new range of applications, it also reduces response times on the bus by up to 90 %.

• Isochronous mode enables clock synchronous control in masters and slaves, irrespective of the bus load. The function enables highly precise positioning processes with clock deviations of less than a microsecond. All participating device cycles are synchronized to the bus master cycle through a "global control" broadcast message. A special sign of life (consecutive number) allows monitoring of the synchronization.

• Clock control synchronizes all stations to a system time with a deviation of less than one millisecond. This allows the precise tracking of events. This is particularly useful for the acquisition of timing functions in networks with numerous masters. It facilitates the diagnostics of faults as well as the chronological planning of events.

• Upload and download allows the loading of any data area in a field device, irrespective of size, with a single command. This enables, for example, programs to be updated or devices replaced without the need for manual loading processes.

Input data via broadcast Output data Slave-to-slave communcation PROFIBUS DP Master Class 1 Publisher e.g. light array

Slave Subscriber e.g. drive Slave Subscriber e.g. drive Slave

2.2.3

Application profiles

PROFIBUS offers a range of application profiles that simplify its use in specific industries or applications. Profiles are manufacturer and user specifications that determine properties,

performance features and behavior for a particular set of devices or system. They take into account application, field device type characteristics, control features and the means of integration (engineering). Conformance with the profile facilitates device interoperability and

interchangeability. A profile may encompass only a few specifications for a specific device class or extend to a set of comprehensive application specifications for a specific industry.

PROFIBUS makes a distinction between common application profiles with implementation options for different applications, application profiles and system and master profiles. The common profiles include, for example, PROFIsafe, Redundancy and Time Stamp. PROFIdrive, SEMI or PA Devices are examples of application profiles. The system and master profiles describe the system

performance that is available to field devices.

A short description of PROFIsafe and PROFIdrive follows this section. More information on the other profiles can be found on the PROFIBUS web site www.profibus.org.

2.2.4

PROFIsafe

PROFIsafe is an optional, common application profile that allows safety-relevant devices to be connected to the same single transmission line as standard devices. These then communicate with an additional safety programmable logic controller or a combined standard/safety-controller. For applications such as presses, saws, robots, chemical processes, burners etc., special precautions are necessary to avoid risk to operators, environment or investment. Traditionally, safety systems are hard-wired, i.e. based on relays or a similar trusted and tangible technology. In recent years, however, safety automation has seen an influx of microcontrollers, software and communication networks, which have now been proven in use in millions of applications. The basis for their use is laid down in international safety standard IEC 61508. This details the measures required for the detection and management of errors and failures, together with the description of systematic software development processes.

PROFIsafe merges standard automation and safety automation in one technology, thus providing higher efficiency to the user. It is available in products such as programmable and numerical controllers, remote I/Os, laser scanners, light curtains, motor starters, frequency converters, drives, gas and fire sensors etc.. Its safety measures are added to the device as a safety layer on top of the existing PROFIBUS layers in the communication stack. This layer is responsible for the transmission of safety relevant process data (safety application) as well as the unchanged existing standard application for non-safety critical functions, like e.g. diagnosis.

PROFIsafe uses single-channel transfer and its error detection mechanisms are totally independent of the underlying PROFIBUS DP (black channel principle). The safety data are packed in the PROFIBUS telegram frame as a supplement to the standard data. This is then passed completely unmodified from a (safety) sender to a (safety) receiver no matter what kind of transmission system is used. Different industry requirements are taken into account. Factory automation deals with short signals processed at very high speed, while process automation involves longer process values that may take more time. PROFIsafe therefore offers two different process data lengths limited to a maximum of 12 bytes and 122 bytes respectively.

2.2.5

PROFIdrive

PROFIdrive is an application profile that addresses the specific requirements of motion control. It utilises the new functions realised in PROFIBUS Version DP-V2: clock cycle synchronisation and slave-to-slave communication. PROFIdrive allows intelligent drives to be used in decentralised automation structures. Digital servo-drives can also be synchronised and position control loops can be closed via PROFIBUS.

Drive application classes The integration of drives into automation solutions depends strongly on the task of the drive. To simplify use, PROFIdrive defines the following generic application classes:

• Standard drive

In the simplest case, the drive is controlled via a main setpoint (e.g. rational speed) by PROFIBUS. The complete closed-loop speed control is carried out in the drive controller. The application case is employed primarily in the area of conventional drive technology, e.g. in conveying systems.

• Standard drive with technological function

This class is a very flexible variant for realising automation applications. This involves breaking down the entire automation process into several small subprocesses. The automation functions are no longer located exclusively in the central automation drive but can be distributed in the drive controllers. In this respect, PROFIBUS serves as the technology interface. Distribution of automation functions assumes that communication is possible in all directions. Thus slave-to-slave communication is required, e.g. between setpoint cascades, winders and applications for rotational speed synchronisation for continuous web processes.

• Positioning drive

In addition to the drive controller, the drive also contains a position controller. Positioning tasks are forwarded to the drive controller and started by PROFIBUS. Position drives have a very wide scope of application, for example, the twisting on and off of lids in a bottling plant, or the positioning of knives in a foil-cutting maschine.

Device model PROFIdrive defines a device model as it can be found - at least partly - in any drive system. The device comprises multiple functional modules which work together and thereby reflect the intelligence of the drive system. Objects are assigned to these functional modules, which then constitute the interface to the automation process. The objects are described and their functions defined in the profile. Parameters are assigned to the objects, which are collectively referred to as the "profile parameters". These include such functions as fault buffers, drive control, device identification, process data configuration and the overall parameter list.

All other parameters, which can number more than 1000 in the case of complex devices, are manufacturer-specific. This provides the producers with the utmost flexibility in realising control functions such as ramp-function generators. The profile does not determine the parameters of the latter, although it does determine its interface to the control program through the control word. This means that the control system remains identical, even if a user changes the drive manufacturer. Since control and parameter creation tools are manufacturer-specific, they can determine and visualise all the parameter information either directly from the drive or from a device description file. Central motion control Robotics and tool maschine applications call for a coordinated motional sequence of muliple drives.

The motion is controlled mostly with the aid of a central numerical control system (CNC). The position control loop is closed via the bus. The clock cycle synchronisation from PROFIBUS Version DP-V2 is employed in order to synchronise the clock pulses of the position controller in the control system and the controllers in the devices. The stiffness and the dynamics of the control loop can be increased significantly by simple means with the aid of the new "dynamic servo control" position control concept that is also decripted in the profile. Thanks to this concept, even highly demanding applications with linear motors can be realised.

2.2.6

Integration technologies

Modern field devices in both Factory and Process Automation provide a wide range of information and execute functions that were previously in the domain of PLCs and control systems. For this reason, tools for commissioning, maintenance, engineering, and parameterization of these devices require an exact and complete description of device data and functions. This includes type of application function, configuration parameters, range of values, units of measurement, default values, limit values, identification, etc. The same applies to the controller/control system, the device-specific parameters and data formats of which must also be made known (integrated) to ensure error-free data exchange with the field devices.

PROFIBUS has developed a number of methods and tools ("integration technologies", GSD, EDD and DTM) which enable standardization of device management. The performance range of these tools is optimized to specific tasks (simplest handling, device-tuning at runtime,etc.), which has given rise to the term scaleable device integration. GSD and EDD are both types of "Electronic device data sheets", developed with different languages, whilst a DTM (Device Type Manager) is a software component containing specific field device functions for parameterization, configuration, diagnostics and maintenance, generated by mapping and to be used together with the universal software interface FDT (Field Device Tool), which is able to implement software components. More information on GSD files are to be found in Chapters 3 and 4. Information on EDD can be found on the PROFIBUS site www-profibus.com. A short overview of FDT technology is to be found in Section 2.4.

2.2.7

Quality assurance

In order for PROFIBUS devices of different types and manufacturers to correctly fulfil their tasks in the automation process, it is essential to ensure error-free exchange of information over the bus. This requires an implementation of communications protocol and application profiles in compliance with the standard. To ensure that this requirement is fulfilled, the PNO has established a quality assurance procedure, whereby on the basis of test reports, certificates are issued to devices that successfully complete the test .

The certification procedure is based on European standard EN 45 000. The PROFIBUS User Organization has approved independent test laboratories in accordance with the specifications of this standard. Only these test laboratories are authorized to carry out device tests that form the basis for certification. The test procedure, which is the same for all test laboratories, is made up of several parts:

• GSD/EDD Check: ensures that the device description files comply to the specification. • Hardware Test: tests the electrical characteristics of the device’s PROFIBUS interface for

compliance to the specifications. This includes terminating resistors, suitability of the implemented drivers and other modules and the quality of line level.

• Function Test: examines the bus access and transmission protocol and the functionality of the test device.

• Conformity Test: forms the main part of the test. The object is to test conformity of the protocol implementation with the standard.

• Interoperability Test: checks the test device for interoperability with PROFIBUS devices of other manufacturers in a multi-vendor plant. This checks that the functionality of the plant is maintained when the test device is added. Operation is also tested with different masters. Once a device has successfully passed all the tests, the manufacturer can apply for a certificate from the PROFIBUS User Organization. Each certified device contains a certification number as a reference. The certificate is valid for 3 years but can be extended after the devices undergoes a further test.

2.3

PROFIBUS PA

PROFIBUS PA (Process Automation) is an extension of PROFIBUS DP tailored to the requirements of process automation. It has two main characteristics:

• Participants can draw (intrinsically safe) power from the bus

• Data transfer is handled according to the international standard IEC 61158-2.

PROFIBUS PA was designed to provide an economic and versatile replacement for convention process control systems, as shown in Fig. 2-13.

Fig. 2-13: Signal transmission: conventional and via PROFIBUS PA

One obvious advantage of PROFIBUS is the substution of point-to-point wiring, marshalling racks, barriers and power supplies by a single bus cable. The technology also leaves a much smaller footprint in the control cabinet.

The other benefits are less tangible, but more important economically. Digital communication allows comfortable commissioning of field devices from the control room. Individual devices can not only be configured from a personal computer but the settings can also be archived centrally. If there are several identical measuring points in an application, the stored parameters can be downloaded to the devices. An individual configuration of each device is no longer necessary. Other benefits lie in operation and maintenance. PROFIBUS PA devices (and their DP equivalents) offer more information. Every parameter in the device can be accessed, provided an appropriate tool is available. By using Endress+Hauser’s FieldCare asset management tool, for instance, the device status can be monitored and reports on device health can be generated as desired. The device serial number can also be read, and linked via Internet to a common equipment record at Endress+Hauser that contains the device history. The same parameter also gives access to spare parts and e-business

Conventional Co ntrol room Fi el d PROFIBUS PA connectors

process-near component PNC process-near component PNC I/O assemblies bus couplerEx [i]

marshalling rack

marshalling rack

junction box

PROFIBUS PA in process engineering

Most manufacturing facilities have a mixture of tasks which are associated with both process and factory automation:

• Process automation: measurement, actuation, control... • Factory automation: filling, storage, conveyance, drives...

For this reason, Endress+Hauser devices installed in a factory will be integrated into PROFIBUS DP, PROFIBUS PA or mixed systems.

Fig. 2-14: Prozess automation with PROFIBUS DP and PROFIBUS PA

Fig. 2-14 shows a typical architecture:

• The process is controlled by a process control system or a programmable logic controller (PLC). The control system or PLC serves as a Class 1 master. It uses the cyclic services to acquire measurements and output control commands. The operating program, e.g. FieldCare, serves as a Class 2 master. It uses the acyclic services and serves to configure the bus participants during installation and normal operation.

• The PROFIBUS DP system is used to handle the communication at the control level. Drives, remote I/Os etc. may all be found upon the bus. It is also possible to connect externally powered field devices to this level, e.g. the flowmeters Promass and Promag. PROFIBUS DP ensures that data are quickly exchanged, whereby in mixed PROFIBUS DP/PA systems the baudrate supported by the segment coupler is often the limiting factor.

• PROFIBUS PA is used at field level. The segment coupler serves both as interface to the PROFIBUS-DP system and as power supply for the PROFIBUS PA field devices. Depending upon the type of segment coupler, the PROFIBUS PA segment can be installed in safe or hazardous areas.

The practical implementation of such an architecture is the subject of this manual.

e.g. FieldCare PLC / PLS

process control system

PROFIBUS DP PROFIBUS PA MBP segment coupler RS 485 up to 12 Mbit/s Non-hazardous area

Explosion-hazardous area MBP_{31,25 kBit/s}

2.3.1

Operating principle

The PROFIBUS PA bus system is powered by a segment coupler. The field devices function as current sinks and draw a direct current of about 10 mA from the bus cable (some participants require more). This current supplies the energy necessary for operation. If a field device transmits data, it does so by modulating the current by ±9 mA. The functional principle is displayed in Fig 3.8. When it is transmitting data, the fieldbus acts as an ohmic resistance. Since the device does not output power, the intrinsic safety of a bus segment is largely determined by the current and voltage limitations placed on the bus power supply (segment coupler).

In order that a field device does not block the bus should it fail, its maximum current consumption is limited by the so-called fault disconnection electronics (FDE). This current must be considered when the segment is planned. See corresponding examples in Chapter 5.6.

Fig. 2-15: Function of a PROFIBUS PA device

Fault disconnection electronics

An important requirement for participants on a PROFIBUS PA segment, is that a defective device may not detrimentally effect the functioning of the system. The fault disconnection electronics ensure that high current consumption is not possible. An electronic circuit detects the rise in the basis current above the specified manufacturer's value and either limits the current consumption or isolates the participant from the bus. The increase in basic current above the normal value in the event of a fault is designated the fault current.

mac. current field device current

basic

fault current

2.3.2

Applications in hazardous areas

The explosion protection concept for the PROFIBUS PA fieldbus is based on the type of protection "intrinsic safety i". In contrast to other types of explosion protection, intrinsic safety is not confined to the individual unit, but extends over the entire electrical circuit. All circuits connected to the PROFIBUS PA fieldbus must be realised with type of protection "intrinsic safety", i.e. all devices and terminators that are installed in hazardous areas as well as all associated electrical apparatus (e.g. PA links or segment couplers) must be approved for the corresponding atmospheres.

FISCO model In order to reduce the proof of intrinsic safety of the fieldbus system, comprising different devices from different vendors, to a justifiable level, the German PTB and various equipment manufacturers developed the FISCO model (Fieldbus Intrinsically Safe COncept). Further information on FISCO is to be found in Chapter 3.8.

The basic idea is that only one device supplies power to a particular fieldbus segment. The model determines the boundary conditions. The field devices are divided into those that draw their power from the bus itself and those that must be powered locally. In addition to the type of protection "intrinsic safety", the latter devices, which require more energy, must also exhibit a further type of protection. The auxiliary energy required by the segment coupler and the locally powered devices is galvanically isolated from the intrinsically safe circuits.

As is the case for all intrinsic circuits, special precautions must be observed when installing the bus. The aim is to maintain the separation between the intrinsically safe and all other circuits.

Grounding The intrinsically safe fieldbus circuit is operated earth-free, which does not preclude that individual sensor circuits can be connected to ground. If a overvoltage protector is installed before the device, it must be bonded to the plant grounding system in accordance with the instructions in the certificate or device manual. Particular attention must be paid to the grounding of the conducting cable screening because if it is to be earthed at several positions, a high integrity plant grounding system must be present.

Category The category of the intrinsically safe field bus is determined by the circuit with the worst rating, i.e. if the fieldbus circuit of one device has the type of protection EEx ib, then the whole fieldbus falls in the category ib. Devices that must be connected to a circuit with type of protection EEx ia (requirements as per certificate) may not be operated on field bus circuits with type of protection ib. Only circuits that are connected directly to the fieldbus must be considered here.

Explosion group Devices that are approved for different explosion groups (IIC, IIB or IIA) can be operated on the same segment. The permissible explosive atmosphere allowed at a particular device is determined by the type of protection of that device as well as the explosion group for which the segment coupler is approved. All devices and terminators that are installed in hazardous areas as well as all associated electrical apparatus (e.g. PA links or segment couplers) must be approved for the corresponding atmospheres, e.g. PTB, BVS, FMRC, CSA etc.).

2.4

Field Device Tool (FDT)

Field Device Tool (FDT) provides a standard interface, open to all communication protocols and software environments that allows any device to be accessed from any host through any protocol. The essential parts of FDT technology are the frame application and the so-called Device Type Managers (DTMs), which are available for field devices and communication equipment, see Fig. 2-16 The two components could be likened to the Print Manager in a Windows Office program and the Print Drivers that must be installed to make printers work and which contain a graphical user interface for their configuration.

Fig. 2-16: Schematic diagram of FDT frame

FDT Frame The FDT frame communicates with the hosting or stand-alone application and the device drivers via a set of standardised interfaces. All data are exchanged through these interfaces, including those generated within the application for engineering, DTM management and device configuration. It is no longer necessary to use proprietary interfaces to operate devices or build up communication paths. Frame applications can be device configuration tools, control system-engineering tools, operator consoles or asset management tools. The frame application is also open to all

communication technologies, e.g. for HART, PROFIBUS and FOUNDATION Fieldbus, see Fig 2-16. Proprietary service bus protocols can also be integrated simply into the frame application because of the standardised interface.

Device DTM The device DTM is a software driver developed by the device manufacturer for each of his devices or group of devices. The DTM encapsulates all the device-specific data, functions and management rules such as the device functions, its communication capabilities, internal data structure and dependencies as well as the user interface elements. It provides functions for accessing device parameters, configuring and operating the devices, calibrating, and diagnosing problems. DTMs can range from a simple user interface for setting device parameters to a highly sophisticated application. They may perform complex calculations for diagnosis and maintenance purposes or display results in the form of curves, trends and other graphical elements.

Communication DTM For communication equipment, such as gateways, multiplexers and other hardware interfaces a CommDTM is required. Like any communication driver, this converts data from one protocol to another, but with the difference that the integration into the system is via a standardised FDT rather than a proprietary interface. This means that users wishing to integrate existing communication equipment into a FDT frame application require only the corresponding CommDTMs. Similarly, vendors need only modify their existing drivers to include a FDT interface and their equipment can

FDT frame program Network configuration Navigation User Management DTM Management Data Management Communication Interfaces HART, PROFIBUS, FF DTM: Device Type Manager

FDT also includes the concept of 'Nested Communication', so that with the aid of CommDTMs, the communication hierarchies found in the plant can be replicated simply in the hosting configuration tool. In this way, the FDT architecture eliminates the integration problems that normally occur when different devices must communicate with each other. It also provides transparent access to data at all system levels.

Fig. 2-17: FDT/DTM Technology - Fieldbus- and device management

The FDT standard uses XML and of is modular construction, each standardised interface reflecting a certain functionality such as configuration or display of measured values. This scalable approach allows DTMs to be developed that exactly match device capabilities and keep up improvements within its life-cycle. There is no reduction of functionality here. FDT is also extendable: new interfaces can be added to cater for functional system enhancements. Not only does this ensure that the standard will keep pace with technical advance, it also ensures that future developments will not affect existing solutions.

DTM Production A Device Type Manager file can written from scratch or be produced from a EDD or HART DD file by running the latter through a special DTM compiler. The Comm DTM is a separate entity that is used to map the communication infrastructure existing in the field. The DTM compilation process is largely automatic and as long as an EDD or HCF DD file exists for the device, a corresponding DTM can be produced. This makes the integration of legacy HART or PROFIBUS devices into an FDT frame application a practical proposition. The FDT tool can then run in parallel to the existing system device configuration tool. For new FDT based installations, the frame application may be stand-alone or integrated into the control system. This has enormous benefits for the user, since he has freedom of choice in the components he uses. Any device or communication component with a device DTM or Comm DTM will operate in any FDT-based configuration tool. Seen for the operators point of view: a single FDT frame can be used to operate a range of devices from a number of different vendor. FDT-Application e.g. FieldCare PLC Segment coupler PROFIBUS PA PROFIBUS DP DTM DTM DTM DTM DTM DTM Communication-Device-DTMs& 4...20 mA HART Engineering tool PROFIBUS PA-Slaves Remote I/O DTM

FDT Joint Interest Group The non profit making FDT Joint Interest Group is an open collaboration of international automation companies for the proliferation of FDT/DTM technology. The group is open to all companies and organizations that wish to participate. The mission of the FDT Joint Interest Group is to promote the acceptance and usage of FDT technology in the factory automation industry, process automation industry and hybrid application industry.

Endress+Hauser is a founding member of the FDT Joint Interest Group and servers on the Marketing and Steering Committees. The PROFIBUS User Organisation (PNO) has granted to the FDT Joint Interest Group ownership rights to use the technology. PNO is the association of users of Profibus technology. FDT technology is available to all companies that wish to utilize it.

The Groups headquarters are in Germany/America. For more information on FDT technology and the FDT Joint Interest Group, see web site http://www.fdt-jig.org

3

PROFIBUS DP basics

As far as PROFIBUS systems in process engineering are concerned, the versions PROFIBUS DP (variant DP-V1) and PROFIBUS PA are of interest. This chapter describes the basics of PROFIBUS DP.

The chapter is structured as follows: • Synopsis

• Topology

• Bus access method • Network configuration

• Applications in hazardous areas

3.1

Synopsis

Fig. 3-1: PROFIBUS DP-System, Version DP-V1

Application PROFIBUS DP is used primarily for factory automation. In PROFIBUS PA systems for process automation, a PROFIBUS DP system is used at the control level for quick transmission of the data. Here, PROFIBUS DP-V1 is normally used. In addition to the cyclic exchange of data with a PLC, DP-V1 allows the field devices to be configured via acyclic services. The principle technical data for PROFIBUS DP are listed in Table 3-1 below.

Table 3-1: Technical data PROFIBUS DP

Class 1 Master PLC Class 2 Master PROFIBUS DP PROFIBUS DP Slaves e.g. FieldCare Standard IEC 61158

Support PROFIBUS User Organisation e.V. (PNO) Physical layer RS-485 and/or fibre optics

Max. length – max. 1200 m without repeater (RS 485), max. 9 repeaters

– or several kilometers (fibre optics) Participants max. 126, including max. 32 as master Transmission rate 9.6 kBit/s up to 12 MBit/s in defined levels Bus access method Token passing with master-slave

Participants Depending upon the application at hand, the participants in a PROFIBUS DP system might be frequency converters, remote I/Os, actuators, sensors, links, gateways etc. as well as the PLC or process control system. The following Endress+Hauser devices can be connected directly to a PROFIBUS DP system:

Table 3-2: Available Endress+Hauser PROFIBUS DP products Type/Name Function and Application

ASP 2000 Stationary precision water sampler for water and wastewater applications

FieldCare Plant Asset Mangement - universal, FDT-based, operating tool for field devices with PROFIBUS PA/DP and other protocols

Liquisys M pH/ORP, conductivity, oxygen, turbidity, chlorine measurement for water and waste water

Memo-Graph RSG 10 16/7 channel (analog/digital) videographic display recorder for where exact recording is required

Promag 53 Magnetic-inductive flow measurement for inductive liquids Promass 83 Coriolis mass flow measurement for liquids, steam and gases Prosonic DP (FMU 86x) Ultrasonic level and flow measurement for solids and liquids Prosonic Flow 93 Ultrasonic flow measurement for liquids

RMS 621 Energy manager for water and steam with up to 10 inputs for 1-3 applications

Smartec S Measurement of conductivity and concentration in highly conductive liquids

3.2

Topology

PROFIBUS DP is based on a linear topology. For lower data transmission rates, a tree structure is also possible.

Cable (Type A) EN 50 170 specifies two types of bus cable. For transmission rates up to 12 Mbit/s, cable type A is recommended. The specification is given in Table 3-3:

Table 3-3: Specifications of Cable Type A

Structure The following points should be noted when the bus structure is being planned:

• The max. permissible cable length depends upon the transmission rate. For PROFIBUS RS-485 cable of type A (see table 2.3) the dependency is as follows:

• A maximum of 32 participants per segment is allowed

• A terminating resistance must be installed at both ends of every segment (ohmic load 220 Ω) • The cable length and/or the number of participants can be increased by using repeaters • If repeaters are used:

– The first and last segment may contain up to 31 particpants, the segments between repeaters may contain up to 30 participants.

– The maximum distance between two participants is: (NO_REP +1) * Segment length

where = NO_REP = max number of repeaters that may be used in series (dependent on type). Example: According to a manufacturer’s specifications, up to 9 repeaters can be connected in series on a standard line. The maximum distance between two bus participants for a transmission speed of 1.5 MBit/s is thus:

(9+1)*200 m = 2000 m

Terminator 135 Ω to165 Ω at a measuring frequency of 3 MHz to 20 MHz Cable capacitance < 30pF per Meter

Core cross-section > 0.34 mm², corresponds to AWG 22 Cable type twisted pairs, 1x 2, 2x 2 or 1x 4 core Loop resistance 110 Ω per km

Signal attenuation max. 9 dB over the entire length of the segment Screening woven copper sheath or woven sheath and foil sheath

Transmission rate (kBit/s) 9.6; 19.2; 45.45; 93.75 187.5 500 1500 3000; 6000; 12000 Cable length (m) 1200 1000 400 200 100

Spurs A spur is the cable connecting the field device to the T-box on the bus.

"

As a rule of thumb:

• For transmission rates up to 1.5 MBit/s, the total length (sum) of the spurs may not exceed 6.6 m

• Spurs should not be used for transmission rates greater than 1.5 MBit/s. Examples Figs 3-2 and 3-3 show examples for a linear and tree bus structure.

• Fig 3-2. shows that three repeaters are necessary if the PROFIBUS DP system is to be developed to the full. The maximum cable length corresponds to 4x the value quoted in the table above. Since three repeaters are used, the maximum number of participants is reduced to 120.

• Fig 3-3 shows how several repeaters can be used to create a tree structure. The number of participants allowable per segment is reduced by one per repeater.

Fig. 3-2: PROFIBUS DP-system with linear structure

(T = terminator, R = repeater, 1...n = max. number of field devices on a segment)

Fig. 3-3: PROFIBUS DP-system with tree structure

Optical network If the PROFIBUS DP system has to be routed over large distances or in plant with heavy electromagnetic interference, then an optical or mixed optical/copper network can be used. Provided that all participants support them, very high transmission rates are possible. Fig. 3-4 shows a possible structure for an optical network, whereby the technical details can be taken from the PROFIBUS standard.

Fig. 3-4: Example for a mixed optical/RS-485-network (T = terminator, 1...n = field devices (slaves)

Master (PLC) RS 485 copper optical interface module optical interface modulel fibre optics