Programmable Logic Controllers - Dag H Hanssen

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Résumé :

Preface xiv

Part One Hardware 1

1 About PLCs 3

1.1 History 4

1.1.1 More Recent Developments 6

1.2 Structure 7

1.2.1 Inputs and Outputs 10

1.3 PLC Operation 13

1.3.1 Process Knowledge 14

1.3.2 Standard Operations 16

1.3.3 Cyclic, Freewheeling, or Event?Controlled Execution 18

1.4 Test Problems 19

2 Digital Signals and Digital Inputs and Outputs 20

2.1 Introduction 20

2.2 Terminology 21

2.2.1 Discrete, Digital, Logical, and Binary 21

2.2.2 Sensors, Transducers, and Transmitters 22

2.3 Switches 24

2.3.1 Limit Switches 24

2.3.2 Safety Devices 24

2.3.3 Magnetic Switches 25

2.4 Logical Sensors 26

2.4.1 Inductive Sensors 27

2.4.2 Capacitive Sensors 29

2.4.3 Photocells 30

2.4.4 Ultrasonic Sensors 33

2.4.5 Rotating Sensors (Encoders) 34

2.4.6 Other Detection Principles and Sensors 37

2.5 Connection of Logical Sensors 39

2.5.1 Sink/Source 41

2.5.2 Selecting a Sensor with the Proper Type of Output 43

2.6 Properties of Discrete Inputs 44

2.7 Discrete Actuators 45

2.7.1 Relays and Contactors 46

2.7.2 Solenoids and Magnetic Valves 47

2.7.3 Transistor Outputs versus Relay Outputs 49

2.8 Test Problems 50

3 Analog Signals and Analog I/O 52

3.1 Introduction 52

3.2 Digitalization of Analog Signals 53

3.2.1 Filtering 53

3.2.2 A/D Conversion 55

3.3 Analog Instrumentation 58

3.3.1 About Sensors 58

3.3.2 Standard Signal Formats 59

3.3.3 On the 4-20 mA Standard 59

3.3.4 Some Other Properties of Sensors 61

3.4 Temperature Sensors 61

3.4.1 Thermocouple 61

3.4.2 PT100/NI1000 62

3.4.3 Thermistors 64

3.5 Connection 64

3.5.1 About Noise, Loss, and Cabling 64

3.5.2 Connecting Sensors 67

3.5.3 Connection of a PT100 (RTD) 68

3.5.4 Connecting Thermocouples 72

3.6 Properties of Analog Input Modules 72

3.6.1 Measurement Ranges and Digitizing: Resolution 72

3.6.2 Important Properties and Parameters 74

3.7 Analog Output Modules and Standard Signal Formats 75

3.8 Test Problems 76

Part Two Methodic 79

4 Structured Design 81

4.1 Introduction 81

4.2 Number Systems 82

4.2.1 The Decimal Number Systems 82

4.2.2 The Binary Number System 82

4.2.3 The Hexadecimal Number System 83

4.2.4 Binary?Coded Decimal Numbers 85

4.2.5 Conversion between Number Systems 86

4.3 Digital Logic 87

4.4 Boolean Design 91

4.4.1 Logical Functional Expressions 91

4.4.2 Boolean Algebra 93

4.5 Sequential Design 97

4.5.1 Flowchart 97

4.5.2 Example: Flowchart for Mixing Process 99

4.5.3 Example: Flowchart for an Automated Packaging Line 101

4.5.4 Sequence Diagrams 107

4.5.5 Example: Sequence Diagram for the Mixing Process 110

4.5.6 Example: Batch Process 112

4.6 State?Based Design 113

4.6.1 Why Use State Diagrams? 114

4.6.2 State Diagrams 114

4.6.3 Example: Batch Process 117

4.6.4 Example: Level Process 118

4.6.5 Example: Packing Facility for Apples 121

4.7 Summary 124

4.8 Test Problems 125

Part Three IEC 61131?3 131

5 Introduction to Programming and IEC 61131?3 133

5.1 Introduction 133

5.1.1 Weaknesses in Traditional PLCs 134

5.1.2 Improvements with IEC 61131?3 136

5.1.3 On Implementation of the Standard 137

5.2 Brief Presentation of the Languages 138

5.2.1 ST 138

5.2.2 FBD 138

Biographie:
Dag H. Hanssen works as an Assistant Professor in automation at the Institute of Engineering and Safety at the University of Troms?. During the course of his 18 year long career with the university he has taught many different courses, but he now focusses on control technique, process automation and Application Development....

Sommaire:
Dag H. Hanssen works as an Assistant Professor in automation at the Institute of Engineering and Safety at the University of Troms?. During the course of his 18 year long career with the university he has taught many different courses, but he now focusses on control technique, process automation and Application Development....