Programmable Logic Controllers - Dogwood Valley …

1 Programmable LogicControllers:An Emphasis on Design and ApplicationKelvin T. EricksonUniversity of Missouri-RollaDogwoodValleyPress,LLCD edicated to Fran, Esther, and DavidCopyright 2005 Dogwood Valley Press, LLC. All rights portion of this book may be reproduced, stored in a retrieval system, or transmitted inany form or by any means, including electronic, mechanical, photocopying, scanning,recording or otherwise, except as permitted under the 1976 United States Copyright Act,without explicit, prior written permission of the publisher except for brief passagesexcerpted for review and critical book was set in Times New Roman and printed on acid-free in the United States of AmericaISBN 0-9766259-0-3 Dogwood Valley Press, LLC1604 Lincoln LaneRolla.

2 MO 654011-573-426-3507 1 Introduction to Control in System of the Versus Other PLC Summary20 References20 chapter 2 Basic Ladder Logic Ladder Ladder Logic Logic Processor with NC Relay Logic to Ladder Summary64 References65 Problems67 chapter 3 Memory Organization and 61131-3 Memory Quantum/Momentum ControlLogix PLC-5 and SLC-500 S7 Fanuc Summary140 References140 Problems141 chapter 4 Input/Output Modules and Summary192 References192 Problems195 chapter 5 Timers and Timers and Timers and ControlLogix Timers and PLC-5/SLC-500 Timers and S7 Timers and Fanuc Timers and Timers and Counter Summary274 References274 Problems276 chapter 6 Sequential Function Chart in Ladder Reset Questions in the Sequential Design and Single-Step Sequential When PLC Has No Summary360 References365 Problems366 chapter 7 Comparison and of Physical Comparison and Comparison and ControlLogix Comparison and PLC-5/SLC-500 Comparison and S7 Comparison and Fanuc Comparison and Summary512 References513 Problems514 chapter 8 Other Ladder Logic IEC Function Modicon Function ControlLogix Function PLC-5/SLC-500 Function Siemens S7 Function GE Fanuc Function Summary669 References669 Problems672 chapter 9

3 Other Function Chart Register-Based Function Summary759 References759 Problems761 chapter 10 PID Control controller Control PID Function Summary853 References854 Problems856 chapter 11 Function Block 61131-3 Function Block Function Block Function Block S7 Function Block Summary910 ContentsiiiReferences911 Problems913 chapter 12 Structured 61131-3 Structured Structured Structured Structured S7 Structured Control Summary948 References948 Problems950 chapter 13 Instruction 61131-3 Instruction Instruction S7 Instruction Fanuc Instruction Summary971 References971 Problems972 chapter 14 Sequential Function 61131-3 Sequential Function Sequential Function Sequential Function Sequential Function S7 Sequential Function Summary1064 References1064 Problems1065 chapter Troubleshooting I/O Status for Fault Summary1091 References1091ivContentsChapter 16 Sensors and Summary1166 References1166 Problems1168 Appendix - Thermocouple Conversion Polynomial Coefficients1174 chapter 17 Communication (DP, PA, PROFInet)

4 Proprietary Fanuc Proprietary Logic Communication Summary1249 References1249 chapter 18 Human-Machine Panel HMI HMI Summary1277 References1277 chapter 19 Control System Automation Network Processor Summary1297 References1297 ContentsvChapter 20 Selecting a Summary1308 References1309 chapter 21 Control Control Design Control Requirements Summary1400 References1401 Problems1402 chapter 22 Example Handling Chemical Summary1416 References1416 Appendix ANumber Systems and Conversions1417 Appendix BElectrical Diagram Symbols1423 Appendix CPiping and Instrumentation Diagram (P&ID) Symbols1426 Glossary1429 Index1445viContentsPREFACEThe field of automatic control has been undergoing a transformation over the pasttwenty years.

5 Twenty years ago, the engineering undergraduate had a course in feedbackcontrol theory and those interested in control engineering secured a position in theaerospace or chemical industries. Due to various factors, the number of control engineeringpositions in the aerospace industry has been declining, but the number of controlengineering positions in manufacturing has been dramatically increasing to the point thatthe majority of control engineering positions is now in manufacturing and involves book presents the subject of programming industrial Controllers , calledprogrammable Logic Controllers (PLCs) with an emphasis on the design of the texts teach one how to program the PLC in its languages, but little, if any, attention ispaid to how does one attack the problem.

6 Given a set of operational specifications, howdoes one develop the PLC program? This book develops the design process: the tasksinvolved, breaking the program into manageable pieces, standard code for the various parts,and handling the sequential parts of the problem. The emphasis is toward those who will beprogramming of its popularity (now and in the future), ladder Logic is the language that isused for the majority of the text. The industry trend is toward using the IEC 61131-3(formerly IEC 1131-3) standard, and so it is the primary language. However, IEC 61131-3is only a voluntary standard and individual manufacturers have some freedom in theimplementation.

7 Therefore, the Allen-Bradley ControlLogix, Modicon, and Siemens S7implementations of the 61131-3 standard are covered. Because of their large installed base,Allen-Bradley PLC-5/SLC-500 and GE Fanuc PLC languages are also to the limitations of ladder Logic , the IEC 61131-3 standard defines four otherlanguages: function block diagram, structured text, instruction list, and sequential functionchart. These four languages will become more popular in the future. Therefore, this text alsocovers these a typical manufacturing plant may contain discrete, continuous, and batchprocesses, all of these applications are treated in this text, although the emphasis is ondiscrete and continuous processes.

8 The emphasis is on a methodology that can be applied toany automation project, regardless of the , the book contains example problems demonstrating good design addition, these problems are solved with each PLC covered in the book. The textculminates in two full-length case studies where the application of the design techniques toa large problem is book takes a practical approach to the design of PLC control systems. Somemathematical theory is used to backup the presentation on PID Controllers . However, thetheory is not detailed and can be for Chapters 1 and 13, every chapter begins with a scenario that reflects theexperience of the author and his colleagues in the challenging world of factory scenarios present a small problem and the solution and are intended to illustratetroubleshooting main objectives of this text are to teach.

9 PLC programming languages (with emphasis on IEC 61131-3) Approach to sequential problems Good program design practice Simple PID control tuning Introduction to sensors and actuators Factory communications Human-machine interface (HMI) conceptsContent OverviewThe book starts by introducing Programmable Logic Controllers (PLCs) and theirdistinguishing characteristics. Chapters2 5cover basic ladder Logic programming:contact, timer, and counter instructions. As part of the basics, the memory structure of thefive particular PLCs and installation topics are treated. chapter 6 covers ladder logicprogram design for sequential applications, probably the most significant contribution ofthe text.

10 Chapters 7 and 8 treat computation, comparison, and advanced ladder logicinstructions. Alternate sequential implementations in ladder Logic are covered in chapter 9and PID controller tuning is covered in chapter 10. Chapters 11 14 cover the other fourIEC programming languages: function block diagram, statement list, instruction list, andsequential function chart. PLC troubleshooting is covered in chapter 15. Sensors andactuators appear in chapter 16. chapter 17 introduces factory communication interface, often called human-machine interface (HMI), issues are treated inChapter 18. Control system security is addressed in chapter 19 and PLC selection isintroduced in chapter 20.