CONTENIDO
I PLC BASICS 1
1 An Overall Look at Programmable Logic Controllers 3
1-1 Introduction 4
1-2 Definition and History of the PLC 4
1-3 PLC Advantages and Disadvantages 7
1-4 Overall PLC System 9
1-5 CPUs and Programmer/Monitors 11
1-6 PLC Input and Output Modules 14
1-7 Printing PLC Information 19
2 The PLC: A Look Inside 21
2-1 Introduction 22
2-2 The PLC as a Computer 22
2-3 The Central Processing Unit 24
2-4 Solid-State Memory 25
2-5 The Processor 29
2-6 I/O Modules (Interfaces) 31
2-7 Power Supplies 34
3 General PLC Programming Procedures 37
3-1 Introduction 38
3-2 Programming Equipment 38
3-3 Programming Formats 41
3-4 Proper Construction of PLC Ladder Diagrams 43
3-5 Process Scanning Considerations 47
3-6 PLC Operational Faults 50
4 Selecting a PLC 53
4-1 Introduction 54
4-2 Industrial Control and the Rise of the PLC 54
4-3 The PLC versus the PC 55
4-4 Factors to Consider in Selecting a PLC 56
4-5 PLC Manufacturers 63
II BASIC PLC PROGRAMMING 65
5 Programming On-Off Inputs to Produce On-Off Outputs 67
5-1 Introduction 68
5-2 PLC Input Instructions 68
5-3 Outputs: Coils, Indicators, and Others 71
5-4 Operational Procedures 72
5-5 Contact and Coil Input/Output Programming Examples 74
5-6 A Look at Fail-Safe Circuits 82
5-7 Industrial Process Example 83
6 Relation of Digital Logic to Contact/Coil Logic 89
6-1 Introduction 90
6-2 Digital Logic Gates 90
6-3 Boolean Algebra PLC Programming 94
6-4 Conversion Examples 95
7 Creating Ladder Diagrams from Process Control Descriptions 105
7-1 Introduction 106
7-2 Ladder Diagrams and Sequence Listings 106
7-3 Large-Process Ladder Diagram Construction 109
7-4 Flowcharting as a Programming Method 114
III BASIC PLC FUNCTIONS 119
8 Register Basics 121
8-1 Introduction 122
8-2 General Characteristics of Registers 122
8-3 Holding Registers 123
8-4 Input Registers: Single and Group 125
8-5 Output Registers: Single and Group 127
9 PLC Timer Functions 129
9-1 Introduction 130
9-2 PLC Timer Functions 130
9-3 Examples of Timer Function Industrial Applications 136
9-4 Industrial Processing Timing Application 146
10 PLC Counter Functions 153
10-1 Introduction 154
10-2 PLC Counters 154
10-3 Examples of Counter Function Industrial Applications 157
IV INTERMEDIATE FUNCTIONS 165
11 PLC Arithmetic Functions 167
11-1 Introduction 168
11-2 PLC Addition and Subtraction 168
11-3 The PLC Repetitive Clock 174
11-4 PLC Multiplication, Division, and Square Root 174
11-5 PLC Trigonometric and Log Functions 178
11-6 Other PLC Arithmetic Functions 179
12 PLC Number Comparison Functions 183
12-1 Introduction 184
12-2 PLC Basic Comparison Functions 184
12-3 PLC Basic Comparison Function Application 186
12-4 PLC Advanced Comparison Functions 194
13 Numbering Systems and PLC Number Conversion Functions 199
13-1 Introduction 200
13-2 Numbering Systems: Decimal, Binary, and BCD 200
13-3 PLC Conversion Between Decimal and BCD 204
13-4 Octal and Hexadecimal Numbering Systems 205
13-5 Other Numbering and Code Systems 209
V DATA HANDLING FUNCTIONS 215
14 The PLC SKIP and MASTER CONTROL RELAY Functions 217
14-1 Introduction 218
14-2 The SKIP Function and Applications 218
14-3 The MASTER CONTROL RELAY Function and Applications 220
15 Jump Functions 227
15-1 Introduction 228
15-2 Jump with Nonreturn 228
15-3 Jump with Return 228
16 PLC Data Move Systems 239
16-1 Introduction 240
16-2 The PLC MOVE Function and Applications 240
16-3 Moving Large Blocks of PLC Data 244
16-4 PLC Table and Register Moves 244
16-5 Other PLC MOVE Functions 247
17 Other PLC Data Handling Functions 251
17-1 Introduction 254
17-2 PLC FIFO Function 254
17-3 The FAL Function 256
17-4 The One Shot (ONS), Clear (CLR), and SWEEP Functions 256
VI PLC FUNCTIONS WORKING WITH BITS 257
18 PLC Digital Bit Functions and Applications 259
18-1 Introduction 260
18-2 Bit Patterns in a Register 260
18-3 Changing a Register Bit Status 261
18-4 Shift Register Functions 264
18-5 Shift Register Applications 270
19 PLC Sequencer Functions 277
19-1 Introduction 278
19-2 Electromechanical Sequencing 278
19-3 The Basic PLC Sequencer Function 281
19-4 A Basic PLC Sequencer Application with Timing 283
19-5 Other PLC Sequencer Functions 287
19-6 Cascading Sequencers 293
20 Controlling a Robot with a PLC 297
20-1 Introduction 298
20-2 Basic Two-Axis Robot with PLC Sequencer Control 298
20-3 Industrial Three-Axis Robot with PLC Control 302
21 PLC Matrix Functions 311
21-1 Introduction 312
21-2 Applying Matrix Functions to Reduce Program Length 312
21-3 The PLC AND and OR Matrix Functions 312
21-4 The PLC COMPLEMENT and COMPARE Matriz Functions 319
21-5 Combination PLC Matrix Functions 312
VII ADVANCED PLC FUNCTIONS 323
22 Analog PLC Operation 325
22-1 Introduction 326
22-2 Types of PLC Analog Modules and Systems 326
22-3 PLC Analog Signal Processing 328
22-4 BCD or Multibit Data Processing 331
22-5 PLC Analog Output Application Examples 332
23 PID Control of Continuous Processes 341
23-1 Introduction 342
23-2 PID Principles 342
23-3 Typical Continuous Process Control Curves 344
23-4 PID Modules 347
23-5 Typical PID Functions 348
24 Networking PLCs 353
24-1 Introduction 354
24-2 Levels of Industrial Control 354
24-3 Types of Networking 356
24-4 Network Communications 358
24-5 Cell Control by PLC Networks 360
VIII RELATED TOPICS 367
25 Alternative Programming Languages 369
25-1 Introduction 370
25-2 Ladder Logic and Beyond 370
25-3 BASIC: A Step Up 371
25-4 State Languages: High-Level Programming for the PLC 373
26 PLC Auxiliary Commands and Functions 379
26-1 Introduction 380
26-2 MONITOR Mode Functions 380
26-3 FORCE Mode Functions 382
26-4 PRINT Functions 383
27 PLC Installation, Troubleshooting, and Maintenance 389
27-1 Introduction 390
27-2 Consideration of the Operating Environment 390
27-3 Receiving Check, Testing, and Assembly 391
27-4 Electrical Connecting, Grounding, and Suppression 393
27-5 Circuit Protection and Wiring 395
27-6 Troubleshooting PLC Malfunctions 399
27-7 PLC Maintenance 403
Appendix 407
A PLC Manufacturers 407
B Operation Simulation and Monitoring 411
C Commonly Used Circuit Symbols 415
D Major PLC Instruction, Function, and Word Codes by Typical Manufacturers 421
Glossary 423
Bibliography 435
Index 439