Automating Manufacturing Systems
with PLCs
(Version 6.0, August 11, 2009)
Hugh Jack
Copyright (c) 1993-2009 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 may be included with this documentation, or is available on-line at the GNU website (http://www.gnu.org).
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://sites.google.com/site/automatedmanufacturingsystems/
1. INTRODUCTION 1
2. PROGRAMMABLE LOGIC CONTROLLERS 5
2.1 INTRODUCTION 5
2.1.1 Ladder Logic 5
2.1.2 Programming 9
2.1.3 PLC Connections 12
2.1.4 Ladder Logic Inputs 14
2.1.5 Ladder Logic Outputs 14
2.2 A CASE STUDY 15
2.3 SUMMARY 16
2.4 PRACTICE PROBLEMS 16
2.5 ASSIGNMENT PROBLEMS 17
2.6 PRACTICE PROBLEM SOLUTIONS 19
3. PLC HARDWARE 21
3.1 INTRODUCTION 21
3.2 INPUTS AND OUTPUTS 22
3.2.1 Inputs 23
3.2.2 Output Modules 26
3.3 RELAYS 32
3.4 A CASE STUDY 33
3.5 ELECTRICAL WIRING DIAGRAMS 34
3.5.1 JIC Wiring Symbols 36
3.6 SUMMARY 39
3.7 PRACTICE PROBLEMS 40
3.8 ASSIGNMENT PROBLEMS 43
3.9 PRACTICE PROBLEM SOLUTIONS 45
4. LOGICAL SENSORS 51
4.1 INTRODUCTION 51
4.2 SENSOR WIRING 51
4.2.1 Switches 52
4.2.2 Transistor Transistor Logic (TTL) 52
4.2.3 Sinking/Sourcing 53
4.2.4 Solid State Relays 60
4.3 PRESENCE DETECTION 60
4.3.1 Contact Switches 61
4.3.2 Reed Switches 61
4.3.3 Optical (Photoelectric) Sensors 61
4.3.4 Capacitive Sensors 69
4.3.5 Inductive Sensors 73
4.3.6 Ultrasonic 75
4.3.7 Hall Effect 75
4.3.8 Fluid Flow 75
4.4 SUMMARY 76
4.5 PRACTICE PROBLEMS 76
4.6 ASSIGNMENT PROBLEMS 79
4.7 PRACTICE PROBLEM SOLUTIONS 83
5. LOGICAL ACTUATORS 89
5.1 INTRODUCTION 89
5.2 SOLENOIDS 89
5.3 VALVES 90
5.4 CYLINDERS 92
5.5 HYDRAULICS 94
5.6 PNEUMATICS 96
5.7 MOTORS 97
5.8 OTHERS 97
5.9 SUMMARY 98
5.10 PRACTICE PROBLEMS 98
5.11 ASSIGNMENT PROBLEMS 99
5.12 PRACTICE PROBLEM SOLUTIONS 101
6. BOOLEAN LOGIC DESIGN 103
6.1 INTRODUCTION 103
6.2 BOOLEAN ALGEBRA 103
6.3 LOGIC DESIGN 107
6.3.1 Boolean Algebra Techniques 114
6.4 COMMON LOGIC FORMS 115
6.4.1 Complex Gate Forms 115
6.4.2 Multiplexers 116
6.5 SIMPLE DESIGN CASES 117
6.5.1 Basic Logic Functions 117
6.5.2 Car Safety System 118
6.5.3 Motor Forward/Reverse 119
6.5.4 A Burglar Alarm 119
6.6 SUMMARY 122
6.7 PRACTICE PROBLEMS 123
6.8 ASSIGNMENT PROBLEMS 127
6.9 PRACTICE PROBLEM SOLUTIONS 129
7. KARNAUGH MAPS 141
7.1 INTRODUCTION 141
7.2 SUMMARY 144
7.3 PRACTICE PROBLEMS 144
7.4 ASSIGNMENT PROBLEMS 151
7.5 PRACTICE PROBLEM SOLUTIONS 153
8. PLC OPERATION 161
8.1 INTRODUCTION 161
8.2 OPERATION SEQUENCE 163
8.2.1 The Input and Output Scans 164
8.2.2 The Logic Scan 164
8.3 PLC STATUS 165
8.4 MEMORY TYPES 166
8.5 SOFTWARE BASED PLCS 166
8.6 SUMMARY 167
8.7 PRACTICE PROBLEMS 167
8.8 ASSIGNMENT PROBLEMS 167
8.9 PRACTICE PROBLEM SOLUTIONS 169
9. LATCHES, TIMERS, COUNTERS AND MORE 171
9.1 INTRODUCTION 171
9.2 LATCHES 172
9.3 TIMERS 176
9.4 COUNTERS 184
9.5 MASTER CONTROL RELAYS (MCRs) 187
9.6 INTERNAL BITS 188
9.7 DESIGN CASES 190
9.7.1 Basic Counters And Timers 190
9.7.2 More Timers And Counters 191
9.7.3 Deadman Switch 192
9.7.4 Conveyor 193
9.7.5 Accept/Reject Sorting 194
9.7.6 Shear Press 195
9.8 SUMMARY 197
9.9 PRACTICE PROBLEMS 197
9.10 ASSIGNMENT PROBLEMS 201
9.11 PRACTICE PROBLEM SOLUTIONS 205
10. STRUCTURED LOGIC DESIGN 217
10.1 INTRODUCTION 217
10.2 PROCESS SEQUENCE BITS 218
10.3 TIMING DIAGRAMS 221
10.4 DESIGN CASES 223
10.5 SUMMARY 223
10.6 PRACTICE PROBLEMS 223
10.7 ASSIGNMENT PROBLEMS 225
10.8 PRACTICE PROBLEM SOLUTIONS 229
11. FLOWCHART BASED DESIGN 235
11.1 INTRODUCTION 235
11.2 BLOCK LOGIC 237
11.3 SEQUENCE BITS 243
11.4 SUMMARY 246
11.5 PRACTICE PROBLEMS 247
11.6 ASSIGNMENT PROBLEMS 248
11.7 PRACTICE PROBLEM SOLUTIONS 251
12. STATE BASED DESIGN 261
12.1 INTRODUCTION 261
12.1.1 State Diagram Example 264
12.1.2 Conversion to Ladder Logic 266
Block Logic Conversion 266
State Equations 273
State-Transition Equations 280
12.2 SUMMARY 285
12.3 PRACTICE PROBLEMS 285
12.4 ASSIGNMENT PROBLEMS 290
12.5 PRACTICE PROBLEM SOLUTIONS 297
13. NUMBERS AND DATA 313
13.1 INTRODUCTION 313
13.2 NUMERICAL VALUES 314
13.2.1 Binary 314
Boolean Operations 317
Binary Mathematics 318
13.2.2 Other Base Number Systems 321
13.2.3 BCD (Binary Coded Decimal) 321
13.3 DATA CHARACTERIZATION 322
13.3.1 ASCII (American Standard Code for Information Interchange) 322
13.3.2 Parity 325
13.3.3 Checksums 326
13.3.4 Gray Code 327
13.4 SUMMARY 327
13.5 PRACTICE PROBLEMS 328
13.6 ASSIGNMENT PROBLEMS 330
13.7 PRACTICE PROBLEM SOLUTIONS 331
14. PLC MEMORY 335
14.1 INTRODUCTION 335
14.2 PROGRAM VS VARIABLE MEMORY 335
14.3 PROGRAMS 336
14.4 VARIABLES (TAGS) 337
14.4.1 Timer and Counter Memory 340
14.4.2 PLC Status Bits 342
14.4.3 User Function Control Memory 344
14.5 SUMMARY 345
14.6 PRACTICE PROBLEMS 345
14.7 ASSIGNMENT PROBLEMS 346
14.8 PRACTICE PROBLEM SOLUTIONS 347
15. LADDER LOGIC FUNCTIONS 351
15.1 INTRODUCTION 351
15.2 DATA HANDLING 353
15.2.1 Move Functions 353
15.2.2 Mathematical Functions 355
15.2.3 Conversions 359
15.2.4 Array Data Functions 360
Statistics 360
Block Operations 362
15.3 LOGICAL FUNCTIONS 364
15.3.1 Comparison of Values 364
15.3.2 Boolean Functions 368
15.4 DESIGN CASES 370
15.4.1 Simple Calculation 370
15.4.2 For-Next 370
15.4.3 Series Calculation 371
15.4.4 Flashing Lights 372
15.5 SUMMARY 373
15.6 PRACTICE PROBLEMS 373
15.7 ASSIGNMENT PROBLEMS 375
15.8 PRACTICE PROBLEM SOLUTIONS 377
16. ADVANCED LADDER LOGIC FUNCTIONS 387
16.1 INTRODUCTION 387
16.2 LIST FUNCTIONS 387
16.2.1 Shift Registers 387
16.2.2 Stacks 389
16.2.3 Sequencers 391
16.3 PROGRAM CONTROL 394
16.3.1 Branching and Looping 394
16.3.2 Fault Handling 398
16.3.3 Interrupts 400
16.4 INPUT AND OUTPUT FUNCTIONS 402
16.4.1 Immediate I/O Instructions 402
16.5 DESIGN TECHNIQUES 403
16.5.1 State Diagrams 403
16.6 DESIGN CASES 407
16.6.1 If-Then 407
16.6.2 Traffic Light 408
16.7 SUMMARY 409
16.8 PRACTICE PROBLEMS 409
16.9 ASSIGNMENT PROBLEMS 411
16.10 PRACTICE PROBLEM SOLUTIONS 415
17. OPEN CONTROLLERS 425
17.1 INTRODUCTION 425
17.2 IEC 61131 425
17.3 OPEN ARCHITECTURE CONTROLLERS 427
17.4 SUMMARY 427
17.5 PRACTICE PROBLEMS 427
17.6 ASSIGNMENT PROBLEMS 428
17.7 PRACTICE PROBLEM SOLUTIONS 429
18. INSTRUCTION LIST PROGRAMMING 431
18.1 INTRODUCTION 431
18.2 THE IEC 61131 VERSION 431
18.3 THE ALLEN-BRADLEY VERSION 434
18.4 SUMMARY 438
18.5 PRACTICE PROBLEMS 439
18.6 ASSIGNMENT PROBLEMS 439
18.7 PRACTICE PROBLEM SOLUTIONS 441
19. STRUCTURED TEXT PROGRAMMING 443
19.1 INTRODUCTION 443
19.2 THE LANGUAGE 444
19.2.1 Elements of the Language 445
19.2.2 Putting Things Together in a Program 450
19.3 AN EXAMPLE 455
19.4 SUMMARY 457
19.5 PRACTICE PROBLEMS 457
19.6 ASSIGNMENT PROBLEMS 459
19.7 PRACTICE PROBLEM SOLUTIONS 461
20. SEQUENTIAL FUNCTION CHARTS 465
20.1 INTRODUCTION 465
20.2 A COMPARISON OF METHODS 479
20.3 SUMMARY 479
20.4 PRACTICE PROBLEMS 479
20.5 ASSIGNMENT PROBLEMS 480
20.6 PRACTICE PROBLEM SOLUTIONS 481
21. FUNCTION BLOCK PROGRAMMING 489
21.1 INTRODUCTION 489
21.2 CREATING FUNCTION BLOCKS 491
21.3 DESIGN CASE 492
21.4 SUMMARY 493
21.5 PRACTICE PROBLEMS 494
21.6 ASSIGNMENT PROBLEMS 496
21.7 PRACTICE PROBLEM SOLUTIONS 497
22. ANALOG INPUTS AND OUTPUTS 501
22.1 INTRODUCTION 501
22.2 ANALOG INPUTS 502
22.3 ANALOG OUTPUTS 507
22.4 ANALOG INPUTS AND OUTPUTS WITH CONTROLLOGIX 509
22.4.1 ANALOG INPUTS AND OUTPUTS WITH A PLC-5 511
22.4.2 Pulse Width Modulation (PWM) Outputs 516
22.4.3 Shielding 518
22.5 DESIGN CASES 520
22.5.1 Process Monitor 520
22.6 SUMMARY 520
22.7 PRACTICE PROBLEMS 520
22.8 ASSIGNMENT PROBLEMS 521
22.9 PRACTICE PROBLEM SOLUTIONS 523
23. CONTINUOUS SENSORS 527
23.1 INTRODUCTION 527
23.2 INDUSTRIAL SENSORS 528
23.2.1 Angular Displacement 528
Potentiometers 528
23.2.2 Encoders 530
Tachometers 533
23.2.3 Linear Position 533
Potentiometers 533
Linear Variable Differential Transformers (LVDT) 534
Moire Fringes 535
Accelerometers 537
23.2.4 Forces and Moments 540
Strain Gages 540
Piezoelectric 543
23.2.5 Liquids and Gases 545
Pressure 546
Venturi Valves 546
Coriolis Flow Meter 548
Magnetic Flow Meter 548
Ultrasonic Flow Meter 548
Vortex Flow Meter 549
Positive Displacement Meters 549
Pitot Tubes 549
23.2.6 Temperature 549
Resistive Temperature Detectors (RTDs) 550
Thermocouples 550
Thermistors 552
Other Sensors 554
23.2.7 Light 554
Light Dependant Resistors (LDR) 554
23.2.8 Chemical 555
pH 555
Conductivity 555
23.2.9 Others 555
23.3 INPUT ISSUES 555
23.4 SENSOR GLOSSARY 558
23.5 SUMMARY 559
23.6 REFERENCES 560
23.7 PRACTICE PROBLEMS 560
23.8 ASSIGNMENT PROBLEMS 561
23.9 PRACTICE PROBLEM SOLUTIONS 565
24. CONTINUOUS ACTUATORS 567
24.1 INTRODUCTION 567
24.2 ELECTRIC MOTORS 567
24.2.1 Basic Brushed DC Motors 569
24.2.2 AC Motors 573
24.2.3 Brushless DC Motors 580
24.2.4 Stepper Motors 582
24.2.5 Wound Field Motors 584
24.3 HYDRAULICS 588
24.4 OTHER SYSTEMS 589
24.5 SUMMARY 589
24.6 PRACTICE PROBLEMS 590
24.7 ASSIGNMENT PROBLEMS 590
24.8 PRACTICE PROBLEM SOLUTIONS 593
25. CONTINUOUS CONTROL 595
25.1 INTRODUCTION 595
25.2 CONTROL OF LOGICAL ACTUATOR SYSTEMS 598
25.3 CONTROL OF CONTINUOUS ACTUATOR SYSTEMS 599
25.3.1 Block Diagrams 599
25.3.2 Feedback Control Systems 600
25.3.3 Proportional Controllers 601
25.3.4 PID Control Systems 603
25.4 DESIGN CASES 607
25.4.1 Oven Temperature Control 607
25.4.2 Water Tank Level Control 608
25.5 SUMMARY 610
25.6 PRACTICE PROBLEMS 610
25.7 ASSIGNMENT PROBLEMS 611
25.8 PRACTICE PROBLEM SOLUTIONS 613
26. FUZZY LOGIC 617
26.1 INTRODUCTION 617
26.2 COMMERCIAL CONTROLLERS 622
26.3 REFERENCES 622
26.4 SUMMARY 622
26.5 PRACTICE PROBLEMS 622
26.6 ASSIGNMENT PROBLEMS 623
26.7 PRACTICE PROBLEM SOLUTIONS 625
27. SERIAL COMMUNICATION 627
27.1 INTRODUCTION 627
27.2 SERIAL COMMUNICATIONS 628
27.2.1 RS-232 631
27.2.2 ASCII Functions 633
27.3 PARALLEL COMMUNICATIONS 637
27.4 DESIGN CASES 638
27.4.1 PLC Interface To a Robot 638
27.5 SUMMARY 639
27.6 PRACTICE PROBLEMS 639
27.7 ASSIGNMENT PROBLEMS 639
27.8 PRACTICE PROBLEM SOLUTIONS 641
28. NETWORKING 645
28.1 INTRODUCTION 645
28.1.1 Topology 645
28.1.2 OSI Network Model 647
28.1.3 Networking Hardware 649
28.1.4 Control Network Issues 650
28.2 NETWORK STANDARDS 651
28.2.1 Devicenet 651
28.2.2 CANbus 655
28.2.3 Controlnet 656
28.2.4 Ethernet 657
28.2.5 Profibus 658
28.2.6 Sercos 659
28.3 PROPRIETARY NETWORKS 659
28.3.1 Data Highway 659
28.4 NETWORK COMPARISONS 662
28.5 DESIGN CASES 663
28.5.1 Devicenet 663
28.6 SUMMARY 664
28.7 PRACTICE PROBLEMS 665
28.8 ASSIGNMENT PROBLEMS 666
28.9 PRACTICE PROBLEM SOLUTIONS 667
29. HUMAN MACHINE INTERFACES (HMI) 673
29.1 INTRODUCTION 673
29.2 HMI/MMI DESIGN 674
29.3 SUMMARY 676
29.4 PRACTICE PROBLEMS 676
29.5 ASSIGNMENT PROBLEMS 676
29.6 PRACTICE PROBLEM SOLUTIONS 677
30. ELECTRICAL DESIGN AND CONSTRUCTION 679
30.1 INTRODUCTION 679
30.2 ELECTRICAL WIRING DIAGRAMS 679
30.2.1 Selecting Voltages 683
30.2.2 Grounding 684
30.2.3 Wiring 687
30.2.4 Suppressors 688
30.2.5 PLC Enclosures 689
30.2.6 Wire and Cable Grouping 691
30.3 FAIL-SAFE DESIGN 692
30.4 SAFETY RULES SUMMARY 692
30.5 REFERENCES 694
30.6 SUMMARY 694
30.7 PRACTICE PROBLEMS 694
30.8 ASSIGNMENT PROBLEMS 694
30.9 PRACTICE PROBLEM SOLUTIONS 697
31. SOFTWARE ENGINEERING 699
31.1 INTRODUCTION 699
31.1.1 Fail Safe Design 699
31.2 DEBUGGING 700
31.2.1 Troubleshooting 700
31.2.2 Forcing 701
31.3 PROCESS MODELING 701
31.4 PROGRAMMING FOR LARGE SYSTEMS 705
31.4.1 Developing a Program Structure 705
31.4.2 Program Verification and Simulation 707
31.5 DOCUMENTATION 708
31.6 COMMISIONING 716
31.7 SAFETY 716
31.7.1 IEC 61508/61511 safety standards 716
31.8 LEAN MANUFACTURING 717
31.9 REFERENCES 718
31.10 SUMMARY 718
31.11 PRACTICE PROBLEMS 718
31.12 ASSIGNMENT PROBLEMS 719
31.13 PRACTICE PROBLEM SOLUTIONS 721
32. SELECTING A PLC 723
32.1 INTRODUCTION 723
32.2 SPECIAL I/O MODULES 728
32.3 SUMMARY 731
32.4 PRACTICE PROBLEMS 731
32.5 ASSIGNMENT PROBLEMS 731
32.6 PRACTICE PROBLEM SOLUTIONS 733
Appendix A. COMBINED GLOSSARY OF TERMS 735
A.1 A 735
A.2 B 736
A.3 C 739
A.4 D 743
A.5 E 745
A.6 F 746
A.7 G 747
A.8 H 748
A.9 I 748
A.10 J 750
A.11 K 750
A.12 L 751
A.13 M 751
A.14 N 753
A.15 O 754
A.16 P 755
A.17 Q 757
A.18 R 757
A.19 S 759
A.20 T 761
A.21 U 762
A.22 V 763
A.23 W 763
A.24 X 764
A.25 Y 764
A.26 Z 764
Appendix B. PLC REFERENCES 765
B.1 SUPPLIERS 765
B.2 PROFESSIONAL INTEREST GROUPS 766
B.3 PLC/DISCRETE CONTROL REFERENCES 766
Appendix C. GNU Free Documentation License 771
C.1 PREAMBLE 771
C.2 APPLICABILITY AND DEFINITIONS 771
C.3 VERBATIM COPYING 772
C.4 COPYING IN QUANTITY 773
C.5 MODIFICATIONS 773
C.6 COMBINING DOCUMENTS 775
C.7 COLLECTIONS OF DOCUMENTS 775
C.8 AGGREGATION WITH INDEPENDENT WORKS 776
C.9 TRANSLATION 776
C.10 TERMINATION 776
C.11 FUTURE REVISIONS OF THIS LICENSE 776
C.12 How to use this License for your documents 777