page 0 A C + B C * B B T1 ST2 A⋅= T1 T2 T3 T4 ST1 ST2 ST3 FS = first scan ST1 ST1 T1+()T2⋅ FS+= ST2 ST2 T2 T3++()T1 T4⋅⋅= ST3 ST3 T4 T1⋅+()T3⋅= T2 ST1 B⋅= T3 ST3 CB⋅()⋅= T4 ST2 CB+()⋅= ST2 A ST1 B ST3 C B T1 T2 T3 T4 ST2 C B ST1 T2 ST1 T1 first scan ST2 T1 ST2 T2 T3 ST3 T3 ST3 T4 T4 T1 Automating Manufacturing Systems with PLCs (Version 4.2, April 3, 2003) Hugh Jack page i Copyright (c) 1993-2003 Hugh Jack (jackh@gvsu.edu). Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License". This document is provided as-is with no warranty, implied or otherwise. There have been attempts to eliminate errors from this document, but there is no doubt that errors remain. As a result, the author does not assume any responsibility for errors and omissions, or damages resulting from the use of the information pro- vided. Additional materials and updates for this work will be available at http://clay- more.engineer.gvsu.edu/~jackh/books.html page ii 1.1 TODO LIST 1.4 2. PROGRAMMABLE LOGIC CONTROLLERS . . . . . . . . . . . . . 2.1 2.1 INTRODUCTION 2.1 2.1.1 Ladder Logic 2.1 2.1.2 Programming 2.6 2.1.3 PLC Connections 2.10 2.1.4 Ladder Logic Inputs 2.11 2.1.5 Ladder Logic Outputs 2.12 2.2 A CASE STUDY 2.13 2.3 SUMMARY 2.14 2.4 PRACTICE PROBLEMS 2.15 2.5 PRACTICE PROBLEM SOLUTIONS 2.15 2.6 ASSIGNMENT PROBLEMS 2.16 3. PLC HARDWARE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 3.1 INTRODUCTION 3.1 3.2 INPUTS AND OUTPUTS 3.2 3.2.1 Inputs 3.3 3.2.2 Output Modules 3.7 3.3 RELAYS 3.13 3.4 A CASE STUDY 3.14 3.5 ELECTRICAL WIRING DIAGRAMS 3.15 3.5.1 JIC Wiring Symbols 3.17 3.6 SUMMARY 3.21 3.7 PRACTICE PROBLEMS 3.21 3.8 PRACTICE PROBLEM SOLUTIONS 3.24 3.9 ASSIGNMENT PROBLEMS 3.27 4. LOGICAL SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 4.1 INTRODUCTION 4.1 4.2 SENSOR WIRING 4.1 4.2.1 Switches 4.2 4.2.2 Transistor Transistor Logic (TTL) 4.3 4.2.3 Sinking/Sourcing 4.3 4.2.4 Solid State Relays 4.10 4.3 PRESENCE DETECTION 4.11 4.3.1 Contact Switches 4.11 4.3.2 Reed Switches 4.11 4.3.3 Optical (Photoelectric) Sensors 4.12 4.3.4 Capacitive Sensors 4.19 4.3.5 Inductive Sensors 4.23 4.3.6 Ultrasonic 4.25 4.3.7 Hall Effect 4.25 page iii 4.3.8 Fluid Flow 4.26 4.4 SUMMARY 4.26 4.5 PRACTICE PROBLEMS 4.27 4.6 PRACTICE PROBLEM SOLUTIONS 4.30 4.7 ASSIGNMENT PROBLEMS 4.36 5. LOGICAL ACTUATORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 5.1 INTRODUCTION 5.1 5.2 SOLENOIDS 5.1 5.3 VALVES 5.2 5.4 CYLINDERS 5.4 5.5 HYDRAULICS 5.6 5.6 PNEUMATICS 5.8 5.7 MOTORS 5.9 5.8 OTHERS 5.10 5.9 SUMMARY 5.10 5.10 PRACTICE PROBLEMS 5.10 5.11 PRACTICE PROBLEM SOLUTIONS 5.10 5.12 ASSIGNMENT PROBLEMS 5.11 6. BOOLEAN LOGIC DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 6.1 INTRODUCTION 6.1 6.2 BOOLEAN ALGEBRA 6.1 6.3 LOGIC DESIGN 6.6 6.3.1 Boolean Algebra Techniques 6.13 6.4 COMMON LOGIC FORMS 6.14 6.4.1 Complex Gate Forms 6.14 6.4.2 Multiplexers 6.15 6.5 SIMPLE DESIGN CASES 6.17 6.5.1 Basic Logic Functions 6.17 6.5.2 Car Safety System 6.18 6.5.3 Motor Forward/Reverse 6.18 6.5.4 A Burglar Alarm 6.19 6.6 SUMMARY 6.23 6.7 PRACTICE PROBLEMS 6.24 6.8 PRACTICE PROBLEM SOLUTIONS 6.27 6.9 ASSIGNMENT PROBLEMS 6.37 7. KARNAUGH MAPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 7.1 INTRODUCTION 7.1 7.2 SUMMARY 7.4 7.3 PRACTICE PROBLEMS 7.4 7.4 PRACTICE PROBLEM SOLUTIONS 7.10 page iv 7.5 ASSIGNMENT PROBLEMS 7.16 8. PLC OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 8.1 INTRODUCTION 8.1 8.2 OPERATION SEQUENCE 8.3 8.2.1 The Input and Output Scans 8.4 8.2.2 The Logic Scan 8.4 8.3 PLC STATUS 8.6 8.4 MEMORY TYPES 8.6 8.5 SOFTWARE BASED PLCS 8.7 8.6 SUMMARY 8.7 8.7 PRACTICE PROBLEMS 8.8 8.8 PRACTICE PROBLEM SOLUTIONS 8.8 8.9 ASSIGNMENT PROBLEMS 8.9 9. LATCHES, TIMERS, COUNTERS AND MORE . . . . . . . . . . . . 9.1 9.1 INTRODUCTION 9.1 9.2 LATCHES 9.2 9.3 TIMERS 9.6 9.4 COUNTERS 9.14 9.5 MASTER CONTROL RELAYS (MCRs) 9.17 9.6 INTERNAL RELAYS 9.19 9.7 DESIGN CASES 9.20 9.7.1 Basic Counters And Timers 9.20 9.7.2 More Timers And Counters 9.21 9.7.3 Deadman Switch 9.22 9.7.4 Conveyor 9.23 9.7.5 Accept/Reject Sorting 9.24 9.7.6 Shear Press 9.26 9.8 SUMMARY 9.27 9.9 PRACTICE PROBLEMS 9.28 9.10 PRACTICE PROBLEM SOLUTIONS 9.32 9.11 ASSIGNMENT PROBLEMS 9.44 10. STRUCTURED LOGIC DESIGN . . . . . . . . . . . . . . . . . . . . . . . 10.1 10.1 INTRODUCTION 10.1 10.2 PROCESS SEQUENCE BITS 10.2 10.3 TIMING DIAGRAMS 10.6 10.4 DESIGN CASES 10.9 10.5 SUMMARY 10.9 10.6 PRACTICE PROBLEMS 10.9 10.7 PRACTICE PROBLEM SOLUTIONS 10.10 10.8 ASSIGNMENT PROBLEMS 10.14 page v 11. FLOWCHART BASED DESIGN . . . . . . . . . . . . . . . . . . . . . . . 11.1 11.1 INTRODUCTION 11.1 11.2 BLOCK LOGIC 11.4 11.3 SEQUENCE BITS 11.11 11.4 SUMMARY 11.15 11.5 PRACTICE PROBLEMS 11.15 11.6 PRACTICE PROBLEM SOLUTIONS 11.16 11.7 ASSIGNMENT PROBLEMS 11.26 12. STATE BASED DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1 12.1 INTRODUCTION 12.1 12.1.1 State Diagram Example 12.4 12.1.2 Conversion to Ladder Logic 12.7 Block Logic Conversion 12.7 State Equations 12.16 State-Transition Equations 12.24 12.2 SUMMARY 12.29 12.3 PRACTICE PROBLEMS 12.29 12.4 PRACTICE PROBLEM SOLUTIONS 12.34 12.5 ASSIGNMENT PROBLEMS 12.49 13. NUMBERS AND DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1 13.1 INTRODUCTION 13.1 13.2 NUMERICAL VALUES 13.2 13.2.1 Binary 13.2 Boolean Operations 13.5 Binary Mathematics 13.6 13.2.2 Other Base Number Systems 13.10 13.2.3 BCD (Binary Coded Decimal) 13.11 13.3 DATA CHARACTERIZATION 13.11 13.3.1 ASCII (American Standard Code for Information Interchange) 13.11 13.3.2 Parity 13.14 13.3.3 Checksums 13.15 13.3.4 Gray Code 13.16 13.4 SUMMARY 13.17 13.5 PRACTICE PROBLEMS 13.17 13.6 PRACTICE PROBLEM SOLUTIONS 13.20 13.7 ASSIGNMENT PROBLEMS 13.23 14. PLC MEMORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.1 14.1 INTRODUCTION 14.1 14.2 MEMORY ADDRESSES 14.1 page vi 14.3 PROGRAM FILES 14.2 14.4 DATA FILES 14.3 14.4.1 User Bit Memory 14.9 14.4.2 Timer Counter Memory 14.10 14.4.3 PLC Status Bits (for PLC-5s and Micrologix) 14.12 14.4.4 User Function Control Memory 14.13 14.4.5 Integer Memory 14.14 14.4.6 Floating Point Memory 14.14 14.5 SUMMARY 14.14 14.6 PRACTICE PROBLEMS 14.15 14.7 PRACTICE PROBLEM SOLUTIONS 14.15 14.8 ASSIGNMENT PROBLEMS 14.18 15. LADDER LOGIC FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . 15.1 15.1 INTRODUCTION 15.1 15.2 DATA HANDLING 15.3 15.2.1 Move Functions 15.3 15.2.2 Mathematical Functions 15.5 15.2.3 Conversions 15.10 15.2.4 Array Data Functions 15.11 Statistics 15.12 Block Operations 15.13 15.3 LOGICAL FUNCTIONS 15.15 15.3.1 Comparison of Values 15.15 15.3.2 Boolean Functions 15.21 15.4 DESIGN CASES 15.22 15.4.1 Simple Calculation 15.22 15.4.2 For-Next 15.23 15.4.3 Series Calculation 15.24 15.4.4 Flashing Lights 15.25 15.5 SUMMARY 15.25 15.6 PRACTICE PROBLEMS 15.26 15.7 PRACTICE PROBLEM SOLUTIONS 15.28 15.8 ASSIGNMENT PROBLEMS 15.34 16. ADVANCED LADDER LOGIC FUNCTIONS . . . . . . . . . . . . . 16.1 16.1 INTRODUCTION 16.1 16.2 LIST FUNCTIONS 16.1 16.2.1 Shift Registers 16.1 16.2.2 Stacks 16.3 16.2.3 Sequencers 16.6 16.3 PROGRAM CONTROL 16.9 16.3.1 Branching and Looping 16.9 16.3.2 Fault Detection and Interrupts 16.14 page vii 16.4 INPUT AND OUTPUT FUNCTIONS 16.18 16.4.1 Immediate I/O Instructions 16.18 16.4.2 Block Transfer Functions 16.20 16.5 DESIGN TECHNIQUES 16.22 16.5.1 State Diagrams 16.22 16.6 DESIGN CASES 16.26 16.6.1 If-Then 16.26 16.6.2 Traffic Light 16.27 16.7 SUMMARY 16.28 16.8 PRACTICE PROBLEMS 16.29 16.9 PRACTICE PROBLEM SOLUTIONS 16.31 16.10 ASSIGNMENT PROBLEMS 16.40 17. OPEN CONTROLLERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.1 17.1 INTRODUCTION 17.1 17.2 IEC 61131 17.2 17.3 OPEN ARCHITECTURE CONTROLLERS 17.3 17.4 SUMMARY 17.4 17.5 PRACTICE PROBLEMS 17.4 17.6 PRACTICE PROBLEM SOLUTIONS 17.4 17.7 ASSIGNMENT PROBLEMS 17.4 18. INSTRUCTION LIST PROGRAMMING . . . . . . . . . . . . . . . . . 18.1 18.1 INTRODUCTION 18.1 18.2 THE IEC 61131 VERSION 18.1 18.3 THE ALLEN-BRADLEY VERSION 18.4 18.4 SUMMARY 18.9 18.5 PRACTICE PROBLEMS 18.10 18.6 PRACTICE PROBLEM SOLUTIONS 18.10 18.7 ASSIGNMENT PROBLEMS 18.10 19. STRUCTURED TEXT PROGRAMMING . . . . . . . . . . . . . . . . 19.1 19.1 INTRODUCTION 19.1 19.2 THE LANGUAGE 19.2 19.3 SUMMARY 19.19 19.4 PRACTICE PROBLEMS 19.20 19.5 PRACTICE PROBLEM SOLUTIONS 19.20 19.6 ASSIGNMENT PROBLEMS 19.20 20. SEQUENTIAL FUNCTION CHARTS . . . . . . . . . . . . . . . . . . . 20.1 20.1 INTRODUCTION 20.1 20.2 A COMPARISON OF METHODS 20.16 20.3 SUMMARY 20.16 page viii 20.4 PRACTICE PROBLEMS 20.17 20.5 PRACTICE PROBLEM SOLUTIONS 20.18 20.6 ASSIGNMENT PROBLEMS 20.25 21. FUNCTION BLOCK PROGRAMMING . . . . . . . . . . . . . . . . . . 21.1 21.1 INTRODUCTION 21.1 21.2 CREATING FUNCTION BLOCKS 21.3 21.3 DESIGN CASE 21.4 21.4 SUMMARY 21.4 21.5 PRACTICE PROBLEMS 21.5 21.6 PRACTICE PROBLEM SOLUTIONS 21.5 21.7 ASSIGNMENT PROBLEMS 21.5 22. ANALOG INPUTS AND OUTPUTS . . . . . . . . . . . . . . . . . . . . 22.1 22.1 INTRODUCTION 22.1 22.2 ANALOG INPUTS 22.2 22.2.1 Analog Inputs With a PLC 22.9 22.3 ANALOG OUTPUTS 22.13 22.3.1 Analog Outputs With A PLC 22.16 22.3.2 Pulse Width Modulation (PWM) Outputs 22.18 22.3.3 Shielding 22.20 22.4 DESIGN CASES 22.22 22.4.1 Process Monitor 22.22 22.5 SUMMARY 22.22 22.6 PRACTICE PROBLEMS 22.23 22.7 PRACTICE PROBLEM SOLUTIONS 22.24 22.8 ASSIGNMENT PROBLEMS 22.29 23. CONTINUOUS SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.1 23.1 INTRODUCTION 23.1 23.2 INDUSTRIAL SENSORS 23.2 23.2.1 Angular Displacement 23.3 Potentiometers 23.3 23.2.2 Encoders 23.4 Tachometers 23.8 23.2.3 Linear Position 23.8 Potentiometers 23.8 Linear Variable Differential Transformers (LVDT)23.9 Moire Fringes 23.11 Accelerometers 23.12 23.2.4 Forces and Moments 23.15 Strain Gages 23.15 Piezoelectric 23.18 23.2.5 Liquids and Gases 23.20 page ix Pressure 23.21 Venturi Valves 23.22 Coriolis Flow Meter 23.23 Magnetic Flow Meter 23.24 Ultrasonic Flow Meter 23.24 Vortex Flow Meter 23.24 Positive Displacement Meters 23.25 Pitot Tubes 23.25 23.2.6 Temperature 23.25 Resistive Temperature Detectors (RTDs) 23.26 Thermocouples 23.26 Thermistors 23.28 Other Sensors 23.30 23.2.7 Light 23.30 Light Dependant Resistors (LDR) 23.30 23.2.8 Chemical 23.31 pH 23.31 Conductivity 23.31 23.2.9 Others 23.32 23.3 INPUT ISSUES 23.32 23.4 SENSOR GLOSSARY 23.37 23.5 SUMMARY 23.38 23.6 REFERENCES 23.39 23.7 PRACTICE PROBLEMS 23.39 23.8 PRACTICE PROBLEM SOLUTIONS 23.40 23.9 ASSIGNMENT PROBLEMS 23.42 24. CONTINUOUS ACTUATORS . . . . . . . . . . . . . . . . . . . . . . . . . 24.1 24.1 INTRODUCTION 24.1 24.2 ELECTRIC MOTORS 24.1 24.2.1 Basic Brushed DC Motors 24.2 24.2.2 AC Motors 24.7 24.2.3 Brushless DC Motors 24.12 24.2.4 Stepper Motors 24.14 24.2.5 Wound Field Motors 24.16 24.3 HYDRAULICS 24.19 24.4 OTHER SYSTEMS 24.20 24.5 SUMMARY 24.21 24.6 PRACTICE PROBLEMS 24.21 24.7 PRACTICE PROBLEM SOLUTIONS 24.22 24.8 ASSIGNMENT PROBLEMS 24.22 25. CONTINUOUS CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 25.1 INTRODUCTION 25.1 [...]... 25.26 FUZZY LOGIC 26.1 26.1 26.2 26.3 26.4 26.5 26.6 26.7 27 CONTROL OF LOGICAL ACTUATOR SYSTEMS CONTROL OF CONTINUOUS ACTUATOR SYSTEMS 25.3.1 Block Diagrams 25.3.2 Feedback Control Systems 25.3.3 Proportional Controllers 25.3.4 PID Control Systems DESIGN CASES 25.4.1 Oven Temperature Control 25.4.2 Water Tank Level Control SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM... These systems are more stable, and often lower cost Most continuous systems can be controlled logically But, some times we will encounter a system that must be controlled continuously When this occurs the control system design becomes more demanding When improperly controlled, continuous systems may be unstable and become dangerous When a system is well behaved we say it is self regulating These systems. .. the perfect car with no friction, with no drag, and can predict how it will work perfectly • Non-Linear - Not Linear This is how the world works and the mathematics become much more complex e.g As rocket approaches sun, gravity increases, so control must change • Sequential - A logical controller that will keep track of time and previous events The difference between these control systems can be emphasized... control Early control systems relied upon mechanisms and electronics to build controlled Most modern controllers use a com- plc wiring - 1.3 puter to achieve control The most flexible of these controllers is the PLC (Programmable Logic Controller) Purpose • Most education focuses on continuous control systems • In practice most contemporary control systems make use of computers... continuous control systems • In practice most contemporary control systems make use of computers • Computer based control is inherently different than continuous systems • The purpose of this book is to address discrete control systems using common control systems • The objective is to prepare the reader to implement a control system from beginning to end, including planning and design of hardware and software... relays allow power to be switched on and off without a mechanical switch It is common to use relays to make simple logical control decisions The development of low cost computer has brought the most recent revolution, the Programmable Logic Controller (PLC) The advent of the PLC began in the 1970s, and has become the most common choice for manufacturing controls PLCs have been gaining popularity on the... for controlling complex systems • Flexible and can be reapplied to control other systems quickly and easily • Computational abilities allow more sophisticated control • Trouble shooting aids make programming easier and reduce downtime • Reliable components make these likely to operate for years before failure 2.1.1 Ladder Logic Ladder logic is the main programming method used for PLCs As mentioned before,... are normally drawn in schematic form using a circle to represent the input coil The output contacts are shown with two parallel lines Normally open contacts are shown as two lines, and will be open (non-conducting) when the input is not energized Normally closed contacts are shown with two lines with a diagonal line through them When the input coil is not energized the normally closed contacts will be... diagrams Figure 2.4 A Seal-in Circuit 2.1.2 Programming The first PLCs were programmed with a technique that was based on relay logic wiring schematics This eliminated the need to teach the electricians, technicians and engineers how to program a computer - but, this method has stuck and it is the most common technique for programming PLCs today An example of ladder logic can be seen in Figure 2.5 To... e.g PID BOOLEAN SEQUENTIAL EVENT BASED TEMPORAL e.g COUNTERS e.g FUZZY LOGIC EXPERT SYSTEMS e.g TIMERS Figure 1.1 Control Dichotomy • Continuous - The values to be controlled change smoothly e.g the speed of a car • Logical - The value to be controlled are easily described as on-off e.g the car motor is on-off NOTE: all systems are continuous but they can be treated as logical for simplicity e.g “When . T2 ST1 T1 first scan ST2 T1 ST2 T2 T3 ST3 T3 ST3 T4 T4 T1 Automating Manufacturing Systems with PLCs (Version 4.2, April 3, 2003) Hugh Jack page i Copyright. OF LOGICAL ACTUATOR SYSTEMS 25.4 25.3 CONTROL OF CONTINUOUS ACTUATOR SYSTEMS 25.5 25.3.1 Block Diagrams 25.5 25.3.2 Feedback Control Systems 25.6 25.3.3