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F S = first scan page 0 T1 = ST2 ⋅ A A ST1 T1 B T3 = ST3 ⋅ ( C ⋅ B ) T3 T4 = ST2 ⋅ ( C + B ) T4 T2 ST2 ST2 T2 = ST1 ⋅ B ST3 C *B C + B ST1 = ( ST1 + T1 ) ⋅ T2 + FS ST2 = ( ST2 + T2 + T3 ) ⋅ T1 ⋅ T4 ST3 = ( ST3 + T4 ⋅ T1 ) ⋅ T3 A T1 ST1 B ST3 C Automating Manufacturing Systems T 2 ST2 B with PLCs T3 C T4 B (Version 4.2, April 3, 2003) T2 ST1 ST 1 T1 first scan T1 T4 ST2 ST 2 Hugh Jack T2 T3 T3 ST3 T4 ST 3 T1 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 provided. Additional materials and updates for this work will be available at http://claymore.engineer.gvsu.edu/~jackh/books.html page ii 1.1 2. 2.2 2.3 2.4 2.5 2.6 INTRODUCTION 2.1.1 Ladder Logic 2.1.2 Programming 2.1.3 PLC Connections 2.1.4 Ladder Logic Inputs 2.1.5 Ladder Logic Outputs A CASE STUDY SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 2.1 2.1 2.6 2.10 2.11 2.12 2.13 2.14 2.15 2.15 2.16 PLC HARDWARE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4. 1.4 PROGRAMMABLE LOGIC CONTROLLERS . . . . . . . . . . . . . 2.1 2.1 3. TODO LIST INTRODUCTION INPUTS AND OUTPUTS 3.2.1 Inputs 3.2.2 Output Modules RELAYS A CASE STUDY ELECTRICAL WIRING DIAGRAMS 3.5.1 JIC Wiring Symbols SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 3.1 3.2 3.3 3.7 3.13 3.14 3.15 3.17 3.21 3.21 3.24 3.27 LOGICAL SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 4.1 4.2 4.3 INTRODUCTION SENSOR WIRING 4.2.1 Switches 4.2.2 Transistor Transistor Logic (TTL) 4.2.3 Sinking/Sourcing 4.2.4 Solid State Relays PRESENCE DETECTION 4.3.1 Contact Switches 4.3.2 Reed Switches 4.3.3 Optical (Photoelectric) Sensors 4.3.4 Capacitive Sensors 4.3.5 Inductive Sensors 4.3.6 Ultrasonic 4.3.7 Hall Effect 4.1 4.1 4.2 4.3 4.3 4.10 4.11 4.11 4.11 4.12 4.19 4.23 4.25 4.25 page iii 4.4 4.5 4.6 4.7 5. INTRODUCTION SOLENOIDS VALVES CYLINDERS HYDRAULICS PNEUMATICS MOTORS OTHERS SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 5.1 5.1 5.2 5.4 5.6 5.8 5.9 5.10 5.10 5.10 5.10 5.11 BOOLEAN LOGIC DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 7. 4.26 4.26 4.27 4.30 4.36 LOGICAL ACTUATORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12 6. 4.3.8 Fluid Flow SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS INTRODUCTION BOOLEAN ALGEBRA LOGIC DESIGN 6.3.1 Boolean Algebra Techniques COMMON LOGIC FORMS 6.4.1 Complex Gate Forms 6.4.2 Multiplexers SIMPLE DESIGN CASES 6.5.1 Basic Logic Functions 6.5.2 Car Safety System 6.5.3 Motor Forward/Reverse 6.5.4 A Burglar Alarm SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 6.1 6.1 6.6 6.13 6.14 6.14 6.15 6.17 6.17 6.18 6.18 6.19 6.23 6.24 6.27 6.37 KARNAUGH MAPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 7.1 7.2 7.3 7.4 INTRODUCTION SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS 7.1 7.4 7.4 7.10 page iv 7.5 8. 8.3 8.4 8.5 8.6 8.7 8.8 8.9 INTRODUCTION OPERATION SEQUENCE 8.2.1 The Input and Output Scans 8.2.2 The Logic Scan PLC STATUS MEMORY TYPES SOFTWARE BASED PLCS SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 8.1 8.3 8.4 8.4 8.6 8.6 8.7 8.7 8.8 8.8 8.9 LATCHES, TIMERS, COUNTERS AND MORE . . . . . . . . . . . . 9.1 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.10 9.11 10. 7.16 PLC OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 8.1 8.2 9. ASSIGNMENT PROBLEMS INTRODUCTION LATCHES TIMERS COUNTERS MASTER CONTROL RELAYS (MCRs) INTERNAL RELAYS DESIGN CASES 9.7.1 Basic Counters And Timers 9.7.2 More Timers And Counters 9.7.3 Deadman Switch 9.7.4 Conveyor 9.7.5 Accept/Reject Sorting 9.7.6 Shear Press SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 9.1 9.2 9.6 9.14 9.17 9.19 9.20 9.20 9.21 9.22 9.23 9.24 9.26 9.27 9.28 9.32 9.44 STRUCTURED LOGIC DESIGN . . . . . . . . . . . . . . . . . . . . . . . 10.1 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 INTRODUCTION PROCESS SEQUENCE BITS TIMING DIAGRAMS DESIGN CASES SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 10.1 10.2 10.6 10.9 10.9 10.9 10.10 10.14 page v 11. FLOWCHART BASED DESIGN . . . . . . . . . . . . . . . . . . . . . . . 11.1 11.1 11.2 11.3 11.4 11.5 11.6 11.7 12. 11.1 11.4 11.11 11.15 11.15 11.16 11.26 STATE BASED DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1 12.1 12.2 12.3 12.4 12.5 13. INTRODUCTION BLOCK LOGIC SEQUENCE BITS SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS INTRODUCTION 12.1.1 State Diagram Example 12.1.2 Conversion to Ladder Logic Block Logic Conversion State Equations State-Transition Equations SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 12.1 12.4 12.7 12.7 12.16 12.24 12.29 12.29 12.34 12.49 NUMBERS AND DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1 13.1 13.2 13.3 INTRODUCTION 13.1 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 DATA CHARACTERIZATION 13.11 13.3.1 ASCII (American Standard Code for Information Interchange) 13.11 13.4 13.5 13.6 13.7 14. 13.3.2 Parity 13.3.3 Checksums 13.3.4 Gray Code SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 13.14 13.15 13.16 13.17 13.17 13.20 13.23 PLC MEMORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.1 14.1 14.2 INTRODUCTION MEMORY ADDRESSES 14.1 14.1 page vi 14.3 14.4 14.5 14.6 14.7 14.8 15. 14.2 14.3 14.9 14.10 14.12 14.13 14.14 14.14 14.14 14.15 14.15 14.18 LADDER LOGIC FUNCTIONS . . . . . . . . . . . . . . . . . . . . . . . . 15.1 15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8 16. PROGRAM FILES DATA FILES 14.4.1 User Bit Memory 14.4.2 Timer Counter Memory 14.4.3 PLC Status Bits (for PLC-5s and Micrologix) 14.4.4 User Function Control Memory 14.4.5 Integer Memory 14.4.6 Floating Point Memory SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS INTRODUCTION DATA HANDLING 15.2.1 Move Functions 15.2.2 Mathematical Functions 15.2.3 Conversions 15.2.4 Array Data Functions Statistics Block Operations LOGICAL FUNCTIONS 15.3.1 Comparison of Values 15.3.2 Boolean Functions DESIGN CASES 15.4.1 Simple Calculation 15.4.2 For-Next 15.4.3 Series Calculation 15.4.4 Flashing Lights SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 15.1 15.3 15.3 15.5 15.10 15.11 15.12 15.13 15.15 15.15 15.21 15.22 15.22 15.23 15.24 15.25 15.25 15.26 15.28 15.34 ADVANCED LADDER LOGIC FUNCTIONS . . . . . . . . . . . . . 16.1 16.1 16.2 16.3 INTRODUCTION LIST FUNCTIONS 16.2.1 Shift Registers 16.2.2 Stacks 16.2.3 Sequencers PROGRAM CONTROL 16.3.1 Branching and Looping 16.3.2 Fault Detection and Interrupts 16.1 16.1 16.1 16.3 16.6 16.9 16.9 16.14 page vii 16.4 16.5 16.6 16.7 16.8 16.9 16.10 17. 17.1 17.2 17.3 17.4 17.4 17.4 17.4 INTRODUCTION THE IEC 61131 VERSION THE ALLEN-BRADLEY VERSION SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 18.1 18.1 18.4 18.9 18.10 18.10 18.10 STRUCTURED TEXT PROGRAMMING . . . . . . . . . . . . . . . . 19.1 19.1 19.2 19.3 19.4 19.5 19.6 20. INTRODUCTION IEC 61131 OPEN ARCHITECTURE CONTROLLERS SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS INSTRUCTION LIST PROGRAMMING . . . . . . . . . . . . . . . . . 18.1 18.1 18.2 18.3 18.4 18.5 18.6 18.7 19. 16.18 16.18 16.20 16.22 16.22 16.26 16.26 16.27 16.28 16.29 16.31 16.40 OPEN CONTROLLERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.1 17.1 17.2 17.3 17.4 17.5 17.6 17.7 18. INPUT AND OUTPUT FUNCTIONS 16.4.1 Immediate I/O Instructions 16.4.2 Block Transfer Functions DESIGN TECHNIQUES 16.5.1 State Diagrams DESIGN CASES 16.6.1 If-Then 16.6.2 Traffic Light SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS INTRODUCTION THE LANGUAGE SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 19.1 19.2 19.19 19.20 19.20 19.20 SEQUENTIAL FUNCTION CHARTS . . . . . . . . . . . . . . . . . . . 20.1 20.1 20.2 20.3 INTRODUCTION A COMPARISON OF METHODS SUMMARY 20.1 20.16 20.16 page viii 20.4 20.5 20.6 21. INTRODUCTION CREATING FUNCTION BLOCKS DESIGN CASE SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 21.1 21.3 21.4 21.4 21.5 21.5 21.5 ANALOG INPUTS AND OUTPUTS . . . . . . . . . . . . . . . . . . . . 22.1 22.1 22.2 22.3 22.4 22.5 22.6 22.7 22.8 23. 20.17 20.18 20.25 FUNCTION BLOCK PROGRAMMING . . . . . . . . . . . . . . . . . . 21.1 21.1 21.2 21.3 21.4 21.5 21.6 21.7 22. PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS INTRODUCTION ANALOG INPUTS 22.2.1 Analog Inputs With a PLC ANALOG OUTPUTS 22.3.1 Analog Outputs With A PLC 22.3.2 Pulse Width Modulation (PWM) Outputs 22.3.3 Shielding DESIGN CASES 22.4.1 Process Monitor SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 22.1 22.2 22.9 22.13 22.16 22.18 22.20 22.22 22.22 22.22 22.23 22.24 22.29 CONTINUOUS SENSORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23.1 23.1 23.2 INTRODUCTION 23.1 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 23.3 23.4 23.5 23.6 23.7 23.8 23.9 24. 23.21 23.22 23.23 23.24 23.24 23.24 23.25 23.25 23.25 23.26 23.26 23.28 23.30 23.30 23.30 23.31 23.31 23.31 23.32 23.32 23.37 23.38 23.39 23.39 23.40 23.42 CONTINUOUS ACTUATORS . . . . . . . . . . . . . . . . . . . . . . . . . 24.1 24.1 24.2 24.3 24.4 24.5 24.6 24.7 24.8 25. Pressure Venturi Valves Coriolis Flow Meter Magnetic Flow Meter Ultrasonic Flow Meter Vortex Flow Meter Positive Displacement Meters Pitot Tubes 23.2.6 Temperature Resistive Temperature Detectors (RTDs) Thermocouples Thermistors Other Sensors 23.2.7 Light Light Dependant Resistors (LDR) 23.2.8 Chemical pH Conductivity 23.2.9 Others INPUT ISSUES SENSOR GLOSSARY SUMMARY REFERENCES PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS INTRODUCTION ELECTRIC MOTORS 24.2.1 Basic Brushed DC Motors 24.2.2 AC Motors 24.2.3 Brushless DC Motors 24.2.4 Stepper Motors 24.2.5 Wound Field Motors HYDRAULICS OTHER SYSTEMS SUMMARY PRACTICE PROBLEMS PRACTICE PROBLEM SOLUTIONS ASSIGNMENT PROBLEMS 24.1 24.1 24.2 24.7 24.12 24.14 24.16 24.19 24.20 24.21 24.21 24.22 24.22 CONTINUOUS CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 25.1 INTRODUCTION 25.1