Practical industrial data networks

Practical Industrial Data Networks: Design,

Installation and Troubleshooting

Titles in the series

Practical Cleanrooms: Technologies and Facilities (David Conway)

Practical Data Acquisition for Instrumentation and Control Systems (John Park,

Steve Mackay)

Practical Data Communications for Instrumentation and Control (Steve Mackay,

Edwin Wright, John Park)

Practical Digital Signal Processing for Engineers and Technicians (Edmund Lai)

Practical Electrical Network Automation and Communication Systems (Cobus

Strauss)

Practical Embedded Controllers (John Park)

Practical Fiber Optics (David Bailey, Edwin Wright)

Practical Industrial Data Networks: Design, Installation and Troubleshooting (Steve

Mackay, Edwin Wright, John Park, Deon Reynders)

Practical Industrial Safety, Risk Assessment and Shutdown Systems for

Instrumentation and Control (Dave Macdonald)

Practical Modern SCADA Protocols: DNP3, 60870.5 and Related Systems (Gordon

Clarke, Deon Reynders)

Practical Radio Engineering and Telemetry for Industry (David Bailey)

Practical SCADA for Industry (David Bailey, Edwin Wright)

Practical TCP/IP and Ethernet Networking (Deon Reynders, Edwin Wright)

Practical Variable Speed Drives and Power Electronics (Malcolm Barnes)

Practical Industrial Data Networks:

Design, Installation and

Troubleshooting

Steve Mackay CPEng, BSc(ElecEng), BSc(Hons), MBA

Edwin Wright MIPENZ, BSc(Hons), BSc(Elec Eng)

Deon Reynders Pr.Eng, BSc(ElecEng)(Hons), MBA

John Park ASD

All with IDC Technologies, Perth, Australia

Newnes

An imprint of Elsevier

Linacre House, Jordan Hill, Oxford OX2 8DP

200 Wheeler Road, Burlington, MA 01803

First published 2004

Copyright  2004, IDC Technologies. All rights reserved

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London, England W1T 4LP. Applications for the copyright holder’s written

permission to reproduce any part of this publication should be addressed

to the publisher

British Library Cataloguing in Publication Data

A catalogue record for this book is available from the British Library

ISBN 07506 5807X

Typeset and Edited by Vivek Mehra, Mumbai, India

([email protected])

Printed and bound in Great Britain

For information on all Newnes publications, visit

our website at www.newnespress.com

Contents

Preface xiii

1 Introduction 1

1.1 Introduction 1

1.2 Modern instrumentation and control systems 2

1.3 Open systems interconnection (OSI) model 6

1.4 Protocols 7

1.5 Standards 8

2 Overall methodology 17

2.1 Introduction 17

2.2 Common problems and solutions 17

2.3 General comments on troubleshooting 18

2.4 A specific methodology 19

2.5 Grounding/shielding and noise 20

2.5.1 Sources of electrical noise 20

2.5.2 Electrical coupling of noise 20

2.5.3 Shielding 25

2.5.4 Cable ducting or raceways 27

2.5.5 Cable spacing 27

2.5.6 Earthing and grounding requirements 28

2.5.7 Suppression techniques 29

2.5.8 Filtering 30

3 EIA-232 overview 32

3.1 EIA-232 interface standard (CCITT V.24 interface standard) 32

3.1.1 The major elements of EIA-232 33

3.2 Half-duplex operation of the EIA-232 interface 40

3.3 Summary of EIA/TIA-232 revisions 41

3.4 Limitations 42

3.5 Troubleshooting 42

3.5.1 Introduction 42

3.5.2 Typical approach 43

3.5.3 Test equipment 44

3.5.4 Typical EIA-232 problems 47

3.5.5 Summary of troubleshooting 51

vi Contents

4 EIA-485 overview 53

4.1 The EIA-485 interface standard 53

4.2 Troubleshooting 58

4.2.1 Introduction 58

4.2.2 EIA-485 vs EIA-422 59

4.2.3 EIA-485 installation 60

4.2.4 Noise problems 61

4.2.5 Test equipment 65

4.2.6 Summary 68

5 Current loop and EIA-485 converters overview 69

5.1 The 20 mA current loop 69

5.2 Serial interface converters 70

5.3 Troubleshooting 72

5.3.1 Troubleshooting converters 72

6 Fiber optics overview 74

6.1 Introduction 74

6.1.1 Applications for fiber optic cables 75

6.2 Fiber optic cable components 75

6.3 Fiber optic cable parameters 77

6.4 Types of optical fiber 78

6.5 Basic cable types 80

6.5.1 Aerial cable 80

6.5.2 Underground cable 81

6.5.3 Sub-aqueous cables 81

6.5.4 Indoor cables 81

6.6 Connecting fibers 82

6.6.1 Connection losses 82

6.6.2 Splicing fibers 82

6.6.3 Connectors 83

6.6.4 Connector handling 84

6.6.5 Optical couplers 84

6.7 Splicing trays/organizers and termination cabinets 84

6.7.1 Splicing trays 85

6.7.2 Splicing enclosures 85

6.7.3 Termination in patch panels and distribution frames 86

6.8 Troubleshooting 88

6.8.1 Introduction 88

6.8.2 Standard troubleshooting approach 88

6.8.3 Tools required 89

Contents vii

6.8.4 Fiber installation rules 89

6.8.5 Clean optical connectors 91

6.8.6 Locating broken fibers 91

7 Modbus overview 96

7.1 General overview 96

7.2 Modbus protocol structure 97

7.3 Function codes 98

7.3.1 Read coil or digital output status (function code 01) 99

7.3.2 Read digital input status (function code 02) 99

7.3.3 Read holding registers (function code 03) 100

7.3.4 Reading input registers (function code 04) 101

7.3.5 Force single coil (function code 05) 102

7.3.6 Preset single register (function code 06) 103

7.3.7 Read exception status (function code 07) 104

7.3.8 Loopback test (function code 08) 105

7.3.9 Force multiple coils or digital outputs (function code 0F) 106

7.3.10 Force multiple registers (function code 10) 107

7.4 Troubleshooting 109

7.4.1 Common problems and faults 109

7.4.2 Description of tools used 109

7.4.3 Detailed troubleshooting 110

7.4.4 Conclusion 114

8 Modbus Plus protocol overview 115

8.1 General overview 115

8.2 Troubleshooting 118

8.2.1 Common problems and faults 118

8.2.2 Description of tools used 119

8.2.3 Detailed troubleshooting 119

8.2.4 Conclusion 123

9 Data Highway Plus/DH485 overview 125

9.1 Allen Bradley Data Highway (Plus) protocol 125

9.1.1 Overview of Allen Bradley protocol 125

9.1.2 Physical layer (hardware layer) 126

9.1.3 Full-duplex data link layer 126

9.2 Troubleshooting 134

9.2.1 Introduction 134

9.2.2 Data Highway Plus wiring troubleshooting 134

9.2.3 Data Highway Plus network diagnostics 136

viii Contents

10 HART overview 137

10.1 Introduction to HART and smart instrumentation 137

10.2 HART protocol 138

10.3 Physical layer 139

10.4 Data link layer 141

10.5 Application layer 142

10.6 Troubleshooting 144

11 AS-interface (AS-i) overview 145

11.1 Introduction 145

11.2 Layer 1 – the physical layer 146

11.3 Layer 2 – the data link layer 149

11.4 Operating characteristics 152

11.5 Troubleshooting 152

11.5.1 Introduction 152

11.5.2 Tools of the trade 153

12 DeviceNet overview 155

12.1 Introduction 155

12.2 Physical layer 156

12.2.1 Topology 156

12.3 Connectors 157

12.3.1 Pluggable (unsealed) connector 158

12.3.2 Hardwired (unsealed) connection 158

12.3.3 Mini (sealed) connector 159

12.3.4 Micro (sealed) connector 160

12.4 Cable budgets 160

12.5 Device taps 161

12.5.1 Sealed taps 161

12.5.2 IDC taps 162

12.5.3 Open style taps 162

12.5.4 Multiport open taps 163

12.5.5 Power taps 164

12.6 Cable description 165

12.6.1 Thick cable 165

12.6.2 Thin cable specification 165

12.6.3 Flat cable 166

12.7 Network power 167

12.7.1 General approach 167

12.7.2 Single supply – end connected 168

Contents ix

12.7.3 Single supply – center connected 168

12.7.4 Suggestions for avoiding errors and power supply options 170

12.8 System grounding 170

12.9 Signaling 170

12.10 Data link layer 171

12.10.1 Frame format 171

12.10.2 Medium access 172

12.10.3 Fragmentation 173

12.11 The application layer 174

12.12 Troubleshooting 174

12.12.1 Introduction 174

12.12.2 Tools of the trade 174

12.12.3 Fault finding procedures 177

13 ProfiBus PA/DP/FMS overview 181

13.1 Introduction 181

13.2 ProfiBus protocol stack 183

13.2.1 Physical layer (layer 1) 183

13.2.2 Data link layer (layer 2) 184

13.2.3 Application layer 187

13.2.4 Fieldbus message specification (FMS) 187

13.2.5 Lower layer interface (LLI) 188

13.2.6 Fieldbus management layer (FMA 7) 189

13.3 The ProfiBus communication model 190

13.4 Relationship between application process and communication 190

13.5 Communication objects 191

13.6 Performance 192

13.7 System operation 192

13.7.1 Configuration 192

13.7.2 Data transfer between DPM1 and the DP-slaves 194

13.7.3 Synchronization and freeze modes 194

13.7.4 Safety and protection of stations 195

13.7.5 Mixed operation of FMS and DP stations 195

13.8 Troubleshooting 195

13.8.1 Introduction 195

13.8.2 Troubleshooting tools 195

13.8.3 Tips 198

14 Foundation Fieldbus overview 200

14.1 Introduction to Foundation Fieldbus 200

x Contents

14.2 The physical layer and wiring rules 201

14.3 The data link layer 204

14.4 The application layer 205

14.5 The user layer 206

14.6 Error detection and diagnostics 207

14.7 High-speed Ethernet (HSE) 207

14.8 Good wiring and installation practice with Fieldbus 208

14.8.1 Termination preparation 208

14.8.2 Installation of the complete system 208

14.9 Troubleshooting 210

14.9.1 Introduction 210

14.9.2 Power problems 211

14.9.3 Communication problems 212

14.9.4 Foundation Fieldbus test equipment 215

15 Industrial Ethernet overview 216

15.1 Introduction 216

15.2 10 Mbps Ethernet 217

15.2.1 Media systems 217

15.2.2 Signaling methods 223

15.2.3 Medium access control 223

15.2.4 Frame transmission 223

15.2.5 Frame reception 224

15.2.6 MAC frame format 224

15.2.7 IEEE 802.2 LLC 226

15.2.8 Reducing collisions 227

15.2.9 Design rules 227

15.3 100 Mbps Ethernet 230

15.3.1 Introduction 230

15.3.2 Media access: full-duplex 231

15.3.3 Auto-negotiation 231

15.4 Gigabit Ethernet 233

15.4.1 Introduction 233

15.4.2 Gigabit Ethernet full-duplex repeaters 234

15.4.3 Gigabit Ethernet design considerations 234

15.5 Industrial Ethernet 236

15.5.1 Introduction 236

15.5.2 Connectors and cabling 236

15.5.3 Deterministic versus stochastic operation 237

15.5.4 Size and overhead of Ethernet frame 237

15.5.5 Noise and interference 237

15.5.6 Partitioning of the network 238

Contents xi

15.5.7 Switching technology 238

15.5.8 Active electronics 239

15.5.9 Fast and gigabit Ethernet 239

15.5.10 TCP/IP and industrial systems 240

15.5.11 Industrial Ethernet architectures for high availability 240

15.6 Troubleshooting 241

15.6.1 Introduction 241

15.6.2 Common problems and faults 241

15.6.3 Tools of the trade 241

15.6.4 Problems and solutions 243

15.6.5 Troubleshooting switched networks 255

15.6.6 Troubleshooting fast Ethernet 256

15.6.7 Troubleshooting gigabit Ethernet 256

16 TCP/IP overview 257

16.1 Introduction 257

16.1.1 The Internet layer 259

16.1.2 The host-to-host layer 259

16.1.3 The process/application layer 259

16.2 Internet layer protocols (packet transport) 259

16.2.1 IP version 4 (IPv4) 259

16.2.2 Address resolution protocol (ARP) 262

16.2.3 ICMP 265

16.2.4 ICMP datagrams 265

16.2.5 Routing 267

16.3 Host-to-host layer: End to end reliability 270

16.3.1 TCP 270

16.3.2 UDP 271

16.4 Troubleshooting 272

16.4.1 Introduction 272

16.4.2 Common problems 272

16.4.3 Tools of the trade 272

16.4.4 Typical network layer problems 273

16.4.5 Transport layer problems 275

17 Radio and wireless communications overview 277

17.1 Introduction 277

17.2 Components of a radio link 278

17.3 The radio spectrum and frequency allocation 279

17.4 Summary of radio characteristics of VHF/UHF 281

17.5 Radio modems 282

17.5.1 Modes of radio modems 285

17.5.2 Features of a radio modem 286

xii Contents

17.5.3 Spread spectrum radio modems 287

17.6 Intermodulation and how to prevent it 287

17.6.1 Introduction 287

17.6.2 Intermodulation 288

17.7 Implementing a radio link 289

17.7.1 Path profile 289

17.7.2 RF path loss calculations 292

17.7.3 Transmitter power/receiver sensitivity 293

17.7.4 Signal to noise ratio and SINAD 294

17.7.5 Fade margin 295

17.7.6 Summary of calculations 296

17.7.7 Miscellaneous considerations 296

17.8 Troubleshooting 297

Appendix A Glossary 298

Appendix B Basic terminology 316

Appendix C Practicals 343

Appendix D Miscellaneous industrial protocols overview 402

Appendix E Local services, regulations and standards 406

Index 415

Preface

This is a comprehensive book covering the essentials of troubleshooting and problem solving of

industrial data communications systems including areas such as RS-232, RS-485, industrial protocols

such as Modbus, fiber optics, industrial Ethernet, TCP/IP, DeviceNet and Fieldbus protocols such as

Profibus and Foundation Fieldbus. It can be used very beneficially in conjunction with the IDC

Technologies two-day workshop on the topic.

We have taken all the key troubleshooting and problem-solving skills from experienced engineers

and distilled these into one hard-hitting course to enable the user to solve real industrial

communications problems.

The overall objective of the book is to help identify, prevent and fix common industrial

communications problems. The focus is ‘outside the box’. The emphasis is practical and on material

that goes beyond typical communications issues. Also, on theory and focuses on providing with the

necessary toolkit of skills in solving industrial communications problems whether it be RS-232/RS￾485, Modbus, Fieldbus and DeviceNet or a local area network such as Ethernet. Industrial

communications systems are being installed throughout the plant today from connecting simple

instruments to programmable logic controllers to PCs throughout the business part of the enterprise.

Communications problems range from simple wiring problems to intermittent transfer of protocol

messages.

The communications system on the plant underpins the entire operation. It is critical that there

should be the knowledge and tools to quickly identify and fix problems as they occur, to ensure that

there is a secure and reliable system. No compromise is possible here. This book distills all the tips

and tricks learnt with the benefit of many years of experience. It offers a common approach covering

all of the sections listed below with each standard/protocol having the following structure:

• Quick overview of the standard

• Common problems and faults that can occur

• Description of tools used

• Each of the faults and ways of fixing them are then discussed in detail

The aim is to provide enough knowledge to troubleshoot and fix problems, as quickly as possible.

At the conclusion of this book, you will be able to:

• Identify, prevent and troubleshoot industrial communications problems

• Fix over 60 of the most common problems that occur in RS-232/RS-485,

industrial protocols (incl. Modbus/ Data Highway Plus), industrial Ethernet,

TCP/IP, DeviceNet and Fieldbus (such as Profibus and Foundation Fieldbus)

• Gain a practical toolkit of skills to troubleshoot industrial communications

systems from RS-232, RS-485, fiber optics, Fieldbus to Ethernet

• Analyze most industrial communications problems and fix them

• Fault find your Ethernet and TCP/IP network problems

This book is intended for engineers and technicians who are:

• Instrumentation and control engineers/technicians

• Process control engineers

• Electrical engineers

• System integrators

xiv Preface

• Designers

• Design engineers

• Systems engineers

• Network planners

• Test engineers

• Electronic technicians

• Consulting engineers

• Plant managers

• Shift electricians

A basic knowledge of data communications is useful but not essential.

The structure of the book is listed below. Each chapter is broken down into:

• Fundamentals of the standard or protocol

• Troubleshooting

Chapter 1: Introduction. An introduction to industrial data communications and the various

standards and protocols in use as discussed in this book.

Chapter 2: Overall methodology. A review of the typical symptoms and problems that

occur in industrial data communications. Typical approaches to follow in isolating and correcting

problems that occur.

Chapter 3: EIA-232 overview. A review of the fundamentals of EIA-232 and ways of

fixing problems here.

Chapter 4: EIA-485 overview. A discussion on RS-485 as far as cabling, common mode

voltage, converters, isolation, idle state terminations and control.

Chapter 5: Current loop and EIA-485 converters overview. Problems with

cabling and isolation and how to fix them.

Chapter 6: Fiber optics overview. A review of splicing, interface to cable, connectors,

multimode, monomode, laser versus LED transmitters, driver incompatibility, bending radius and

shock and installation issues.

Chapter 7: Modbus overview. A discussion on the problems with Modbus such as no

response, exception reports, noise and radio interfaces and the lack of physical and application layers

in the definition.

Chapter 8: Modbus Plus protocol overview. Review of typical problems such as

cabling, grounding, shielding, terminators and token passing.