Page 6 - Programmable Logic Controllers, Fifth Edition Mobile 2
P. 6
Contents
Preface .....................................viii 3.8 ASCII Code........................... 54
Acknowledgments .............................xi 3.9 Parity Bit............................. 54
About the Author ............................. xii 3.10 Binary Arithmetic ...................... 55
3.11 Floating Point Arithmetic ................ 57
Chapter 1 Programmable Logic Controllers Review Questions............................. 59
(PLCs): An Overview 1 Problems ................................... 60
1.1 Programmable Logic Controllers ........... 2
1.2 Parts of a PLC.......................... 4 Chapter 4 Fundamentals of Logic 61
1.3 Principles of Operation................... 8 4.1 The Binary Concept .................... 62
1.4 Modifying the Operation ................ 11 4.2 AND, OR, and NOT Functions............ 62
1.5 PLCs versus Computers ................. 11 The AND Function ..................... 62
1.6 PLC Size and Application................ 12 The OR Function....................... 63
Review Questions............................. 15 The NOT Function ..................... 64
Problems ................................... 16 The Exclusive-OR (XOR) Function......... 65
4.3 Boolean Algebra ....................... 65
Chapter 2 PLC Hardware Components 17
4.4 Developing Logic Gate Circuits from Boolean
2.1 The I/O Section........................ 18 Expressions........................... 66
2.2 Discrete I/O Modules ................... 22 4.5 Producing the Boolean Equation for a Given
2.3 Analog I/O Modules .................... 27 Logic Gate Circuit ..................... 66
2.4 Special I/O Modules .................... 31 4.6 Hardwired Logic versus Programmed Logic . 67
2.5 I/O Specifications ...................... 33 4.7 Programming Word Level Logic Instructions. 70
Typical Discrete I/O Module Specifications .. 33 Review Questions............................. 72
Typical Analog I/O Module Specifications . . . 34 Problems ................................... 72
2.6 The Central Processing
Unit (CPU) ........................... 35 Chapter 5 Basics of PLC Programming 74
2.7 Memory Design ....................... 36
2.8 Memory Types ........................ 37 5.1 Processor Memory Organization .......... 75
2.9 Programming Terminal Devices ........... 39 Program Files ......................... 75
2.10 Recording and Retrieving Data............ 39 Data Files ............................ 75
2.11 Human Machine Interfaces (HMIs) ........ 39 5.2 Program Scan ......................... 78
Review Questions............................. 43 5.3 PLC Programming Languages ............ 81
Problems ................................... 45 5.4 Bit-Level Logic Instructions.............. 83
5.5 Instruction Addressing .................. 86
Chapter 3 Number Systems and Codes 46 5.6 Branch Instructions..................... 87
5.7 Internal Relay Instructions ............... 89
3.1 Decimal System ....................... 47 5.8 Programming Examine If Closed and Examine
3.2 Binary System......................... 47 If Open Instructions .................... 90
3.3 Negative Numbers...................... 49 5.9 Entering the Ladder Diagram ............. 91
3.4 Octal System.......................... 49 5.10 Modes of Operation .................... 93
3.5 Hexadecimal System.................... 50 5.11 Connecting with Analog Devices .......... 93
3.6 Binary Coded Decimal (BCD) System...... 51 Review Questions............................. 95
3.7 Gray Code............................ 53 Problems ................................... 96
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