1、ProgrammableControllers4th EditionHughes05.book Page i Tuesday, October 26, 2004 9:00 AMHughes05.book Page ii Tuesday, October 26, 2004 9:00 AMProgrammableControllers4th EditionThomas A. HughesHughes05-front.fm Page iii Thursday, March 22, 2007 10:02 AMNoticeThe information presented in this publica
2、tion is for the general education of the reader. Because neither the author nor the publisher have any control over the use of the information by the reader, both the author and the publisher disclaim any and all liability of any kind arising out of such use. The reader is expected to exercise sound
3、 professional judgment in using any of the information presented in a particular application.Additionally, neither the author nor the publisher have investigated or considered the affect of any patents on the ability of the reader to use any of the information in a particular application. The reader
4、 is responsible for reviewing any possible patents that may affect any particular use of the information presented.Any references to commercial products in the work are cited as examples only. Neither the author nor the publisher endorse any referenced commercial product. Any trademarks or tradename
5、s referenced belong to the respective owner of the mark or name. Neither the author nor the publisher make any representation regarding the availability of any referenced commercial product at any time. The manufacturers instructions on use of any commercial product must be followed at all times, ev
6、en if in conflict with the information in this publication.Copyright 2005 ISA - The Instrumentation, Systems and Automation SocietyAll rights reserved. Printed in the United States of America. 10 9 8 7 6 5 4 3 ISBN 1-55617-899-9No part of this work may be reproduced, stored in a retrieval system, or
7、 transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior writ-ten permission of the publisher.ISA67 Alexander DriveP.O. Box 12277Research Triangle Park, NC 27709Library of Congress Cataloging-in-Publication DataHughes, Thomas A.Program
8、mable controllers / Thomas A. Hughes.- 4th ed.p. cm.ISBN 1-55617-899-9 (hardcover)1. Programmable controllers. I. Title. TJ223.P76H84 2004629.89-dc222004024467Hughes05-front.fm Page iv Tuesday, November 16, 2004 3:21 PMISA Resources for Measurement and Control Series (RMC) Measurement and Control Ba
9、sics, 3rdEdition (2002) Industrial Pressure, Level, and Density Measurement (1995) Industrial Flow Measurement, 3rd Edition (2005) Programmable Controllers, 4thEdition (2005) Control Systems Documentation: Applying Symbols and Identification, 2ndEdition (2005) Industrial Data Communications, 3rdEdit
10、ion (2002) Automation Systems for Control and Data Acquisition (1992) Control System Safety Evaluation and Reliability, 2ndEdition (1998)Hughes05.book Page v Tuesday, October 26, 2004 9:00 AMHughes05.book Page vi Tuesday, October 26, 2004 9:00 AMDEDICATIONThis book is dedicated to my grandson, Ian L
11、ovell Rager.Hughes05.book Page vii Tuesday, October 26, 2004 9:00 AMHughes05.book Page viii Tuesday, October 26, 2004 9:00 AMixContentsPREFACE xiiiABOUT THE AUTHOR xvChapter 1 INTRODUCTION TO PROGRAMMABLE CONTROLLERS 1Introduction, 1Basic Components of Programmable Controllers, 4Chapter 2 BINARY LOG
12、IC FUNDAMENTALS 27Introduction, 27Binary Signals and Codes, 27Numbering Systems, 28Binary Data Codes, 34Binary Logic Functions, 40Logic Function Symbols, 45Electrical Ladder Diagrams, 45Chapter 3 ELECTRICAL AND ELECTRONIC FUNDAMENTALS 53Introduction, 53Fundamentals of Electricity, 53Conductivity, Re
13、sistivity, and Ohms Law, 55Wire Resistance, 56Wire Gauge Sizes, 58Direct and Alternating Current, 59Series Resistance Circuits, 61Parallel Resistance Circuits, 63Wheatstone Bridge Circuit, 65Instrumentation Current Loop, 67Fundamentals of Magnetism, 69Other Control Devices, 79Hughes05.book Page ix T
14、uesday, October 26, 2004 9:00 AMxContentsChapter 4 INPUT/OUTPUT SYSTEMS 83Introduction, 83I/O Circuit Mounting Configurations, 83Discrete Inputs, 84Discrete Outputs, 85I/O Signal Types, 85Sinking and Sourcing Operations, 86Discrete AC Voltage Input Electronic Circuits, 86Discrete AC Input Modules, 8
15、8Direct Current (DC) Input Modules, 88Transistor-Transistor Logic (TTL) Input Modules, 89Discrete AC Output Electronic Circuit, 90Discrete AC Output Module, 91TTL Output Module, 93Isolated AC Output Module, 93Analog I/O Modules, 94Analog Input Modules, 95Analog Output Modules, 96Pulse Counter Input
16、Modules, 98Intelligent I/O Modules, 98Universal Remote I/O Link, 102Designing I/O Systems, 103Chapter 5 MEMORY AND ADDRESSING 109Memory Components and Structure, 109Memory Types, 112Hardware-to-Software Interface, 122Allen-Bradley PLC5 Discrete I/O Addressing, 124Siemens Simatic S7-300 Discrete I/O
17、Addressing, 125Chapter 6 LADDER DIAGRAM PROGRAMMING 129Introduction, 129Basic LD Instruction Set, 130Output Coil Instruction, 132Timer Memory Word Structure, 137Move and Masked Move, 144Arithmetic Operations, 145Chapter 7 ADVANCED LD PROGRAMMING 157Introduction, 157Advanced LD Instructions, 157Chapt
18、er 8 STANDARD PLC PROGRAMMING LANGUAGES 177Introduction, 177International Standard for PLC Languages, 177Hughes05.book Page x Tuesday, October 26, 2004 9:00 AMContents xiSequential Function Chart Language, 179Structured Text Language, 183Instruction List Programming, 185Chapter 9 FUNCTION BLOCK DIAG
19、RAM PROGRAMMING 211Introduction, 211Elements and Box Structure, 211Bit Logic Instructions, 212Timer Instructions, 221Counter Instructions, 230Chapter 10 DATA COMMUNICATION SYSTEMS 245Introduction, 245Basic Communications, 245Transmission Methods, 248Signal Multiplexing, 251Error Control and Checking
20、, 253Communication Protocols, 257Serial Synchronous Transmission, 259ISO/OSI Communications Standard, 267Serial Communications Standards, 269Industrial Control Networks, 272Chapter 11 SYSTEM DESIGN AND APPLICATIONS 277Introduction, 277Process and Mechanical Control Diagrams, 277Process and Machine C
21、ontrol Descriptions, 280Sizing and Selection of a PLC System, 281Control System Diagram, 286I/O Wiring Diagrams, 286Control System Programming, 287Natural Gas Dehydration Application, 288Two-Stage Alternating Pump Application, 299Chapter 12 DESIGN, INSTALLATION, AND MAINTENANCE 305Introduction, 305C
22、ontrol Panel Design, 305Equipment Layout Design, 316System Start-Up and Testing, 317Maintenance Practices, 319Troubleshooting PLC Systems, 321Control System Documentation, 329Appendix A ANSWERS TO EXERCISES 333INDEX 365Hughes05.book Page xi Tuesday, October 26, 2004 9:00 AMHughes05.book Page xii Tue
23、sday, October 26, 2004 9:00 AMxiiiPrefaceSince 1989, this book has been used both as a textbook for programmable logic controller (PLC) courses and for self-study by thousands of professionals. This applications-based book provides a clear and concise presentation of the fundamental principles of pr
24、ogrammable controllers for process and machine control. This fourth edition covers all phases of programmable controller applications from design and programming to installation, maintenance, and start-up. Coverage of all five standard PLC programming languages: Ladder Diagram, Function Block Diagra
25、m, Sequential Function Chart, Instruction List, and Structured Text has been increased in this fourth edition and numerous programming applications and examples have been added to more clearly explain each programming language.The text provides a complete and comprehensive presentation on the design
26、 and programming of programmable controllerbased control systems. The material also includes chapters on binary logic fundamentals, electrical and electronic principles, input and output systems, memory and addressing, programming languages, and data communication. Chapter 11 provides complete cover
27、age of several typical PLC control applications. The final chapter covers design, installation, and maintenance of programmable controllers in detail.All the chapters have been supplemented with new or improved example problems and exercises. Most of the illustrations in the book have been revised a
28、nd improved. Answers to all the exercises have been added at the end of the book to assist students and instructors.I would like to express my appreciation to my wife Ellen for the long hours spent reviewing all four editions. I would also like to thank the technical reviewers for making numerous co
29、nstructive comments that improved the overall presentation of this fourth edition.Hughes05.book Page xiii Tuesday, October 26, 2004 9:00 AMHughes05.book Page xiv Tuesday, October 26, 2004 9:00 AMxvAbout the AuthorThomas A. Hughes, a Senior Member of ISA has 34 years of experience in the design and i
30、nstallation of instrumentation and control systems, including 20 years in the management of instrumentation and control projects for the process and nuclear industries. He is the author of two books: Measurement and Control Basics, 3rd Edition, (2002) and Programmable Controllers, 4th Edition, (2005
31、), both published by ISA. Mr. Hughes received a B. S. in engineering physics from the University of Colorado, and a M.S. in control systems engineering from Colorado State University. He holds professional engineering licenses in the states of Colorado and Alaska, and has held engineering and manage
32、ment positions with Dow Chemical, Rockwell International, EG it is usually located in the same housing as the CPU. The information stored in memory determines how the input and output data will be processed.Memory stores individual pieces of data called bits. A bit has two states: 1 or 0. Memory uni
33、ts are mounted on circuit boards and are usually specified in thousands or “K” increments where 1K is 1024 words (i.e., 210= 1024) of storage space. Programmable controller memory capacity may vary from less than one thousand words to over 64,000 words (64K words) depending on the programmable contr
34、oller manufacturer. The complexity of the control plan will determine the amount of memory required.Although there are several different types of computer memory, they can always be classified as volatile or nonvolatile. Volatile memory will lose its programmed contents if all operating power is los
35、t or removed. Volatile memory is easily altered and quite suitable for most programming applications when supported by battery backup and/or a recorded copy of the program. Nonvolatile memory will retain its data and program even if there is a complete loss of operating power. It does not require a
36、backup system.The most common form of volatile memory is Random Access Memory, or RAM. RAM is relatively fast and provides an easy means to create and store application programs. If normal power is disrupted, PLCs with RAM use battery or capacitor backups to prevent program loss.The Electrically Era
37、sable Programmable Read Only Memory (EEPROM) is a nonvolatile memory that is programmed through application software, which runs on a PC or through a micro PLC hand-held programmer.Hughes05.book Page 12 Tuesday, October 26, 2004 9:00 AMIntroduction to Programmable Controllers 13There are two areas o
38、f memory in the PLC system that the user can access: program files and data files. Program files store the control application program, subroutine files, and the error file. Data files store data associated with the control program, such as input/output status bits, counter and timer preset and accu
39、mulated values, and other stored constants or variables. Together, these two general memory areas are called user or application memory. The processor also has an executive or system memory that directs and performs operational activities such as executing the control program and coordinating input
40、scans and output updates. This process system memory, which is programmed by the PLC manufacturer, cannot be accessed or changed by the user.Power SupplyThe power supply converts AC line voltages to DC voltages to power the electronic circuits in a programmable controller system. These power supplie
41、s rectify, filter, and regulate voltages and currents to supply the correct amounts of voltage and current to the system. The power supply normally converts 120-VAC or 240-VAC line voltage into DC voltages such as +5 VDC, 15 VDC, or +15 VDC.The power supply for a programmable controller system may b
42、e integrated with the processor, memory, and I/O modules into a single housing, or it might be a separate unit connected to the system through a cable. As a system expands to include more I/O modules or special function modules, most programmable controllers require an additional or auxiliary power
43、supply to meet the increased power demand. Programmable controller power supplies are usually designed to eliminate electrical noise present on the AC power and signal lines of industrial plants so that this electrical noise does not introduce errors in the control system. They are also designed to
44、operate properly in the higher temperature, vibration and humidity environments present in most industrial applications.Communication DevicesThe main function communication device or port is to communicate with the programming to enter, modify, and monitor the PLC control plan. In a small stand-alon
45、e PLC, there may be a single serial port to connect with the programming device. However, most PLC systems have more than one communication port or device. In a typical PLC system, there is the standard serial RS-232C port for programming and a vendor proprietary communication network that is used t
46、o transfer information between the remote I/O equipment racks and the other PLCs in the system. In larger PLC systems, there is normally an Ethernet link to communicate with PCs and other networks connected to the system. Hughes05.book Page 13 Tuesday, October 26, 2004 9:00 AM14 Introduction to Prog
47、rammable ControllersEthernet network has started to move onto the factory floor due in part to the confluence of the MIS systems and factory floor machine and process control systems. The widespread use of this type of network in general computer, PCs, telecomm systems, and the Internet has caused r
48、apid advances in PLC Control System applications. One general difference between Ethernet hardware in PCs and in PLCs is the equipment cost. While dropping for factory floor equipment, PC Ethernet hardware is very inexpensive, because most of the computing resource is being supplied by the PC. The P
49、C Ethernet card generally supplies little more than the physical interface to the cable. The typical PLC Ethernet card supplies much of the computing power for the network and therefore is more complex.Programming LanguagesThe programming language lets the user communicate with the programmable controller via a programming device. Programmable controller manufacturers use several different programming languages, but they all convey to the system, by means of instructions, a basic control plan.A control plan or program is defined as a set of instructions that are a
