Programmable Logic Controllers - A Practical Approach to IEC 61131-3 using CoDeSys

Title Page

Copyright Page

Contents

Programmable Logic Controllers

Preface

Part 1 Hardware

Chapter 1 About PLCs

1.1 History

1.1.1 More Recent Developments

1.2 Structure

1.2.1 Inputs and Outputs

1.3 PLC Operation

1.3.1 Process Knowledge

1.3.2 Standard Operations

1.3.3 Cyclic, Freewheeling, or Event-Controlled Execution

1.4 Test Problems

Chapter 2 Digital Signals and Digital Inputs and Outputs

2.1 Introduction

2.2 Terminology

2.2.1 Discrete, Digital, Logical, and Binary

2.2.2 Sensors, Transducers, and Transmitters

2.3 Switches

2.3.1 Limit Switches

2.3.2 Safety Devices

2.3.3 Magnetic Switches

2.4 Logical Sensors

2.4.1 Inductive Sensors

2.4.2 Capacitive Sensors

2.4.3 Photocells

2.4.4 Ultrasonic Sensors

2.4.5 Rotating Sensors (Encoders)

2.4.6 Other Detection Principles and Sensors

2.5 Connection of Logical Sensors

2.5.1 Sink/Source

2.5.2 Selecting a Sensor with the Proper Type of Output

2.6 Properties of Discrete Inputs

2.7 Discrete Actuators

2.7.1 Relays and Contactors

2.7.2 Solenoids and Magnetic Valves

2.7.3 Transistor Outputs versus Relay Outputs

2.8 Test Problems

Chapter 3 Analog Signals and Analog I/O

3.1 Introduction

3.2 Digitalization of Analog Signals

3.2.1 Filtering

3.2.2 A/D Conversion

3.3 Analog Instrumentation

3.3.1 About Sensors

3.3.2 Standard Signal Formats

3.3.3 On the 4–20mA Standard

3.3.4 Some Other Properties of Sensors

3.4 Temperature Sensors

3.4.1 Thermocouple

3.4.2 PT100/NI1000

3.4.3 Thermistors

3.5 Connection

3.5.1 About Noise, Loss, and Cabling

3.5.2 Connecting Sensors

3.5.3 Connection of a PT100 (RTD)

3.5.4 Connecting Thermocouples

3.6 Properties of Analog Input Modules

3.6.1 Measurement Ranges and Digitizing: Resolution

3.6.2 Important Properties and Parameters

3.7 Analog Output Modules and Standard Signal Formats

3.8 Test Problems

Part 2 Methodic

Chapter 4 Structured Design

4.1 Introduction

4.2 Number Systems

4.2.1 The Decimal Number Systems

4.2.2 The Binary Number System

4.2.3 The Hexadecimal Number System

4.2.4 Binary-Coded Decimal Numbers

4.2.5 Conversion between Number Systems

4.3 Digital Logic

4.4 Boolean Design

4.4.1 Logical Functional Expressions

4.4.2 Boolean Algebra

4.5 Sequential Design

4.5.1 Flowchart

4.5.2 Example: Flowchart for Mixing Process

4.5.3 Example: Flowchart for an Automated Packaging Line

4.5.4 Sequence Diagrams

4.5.5 Example: Sequence Diagram for the Mixing Process

4.5.6 Example: Batch Process

4.6 State-Based Design

4.6.1 Why Use State Diagrams?

4.6.2 State Diagrams

4.6.3 Example: Batch Process

4.6.4 Example: Level Process

4.6.5 Example: Packing Facility for Apples

4.7 Summary

4.8 Test Problems

Part 3 IEC 61131-3

Chapter 5 Introduction to Programming and IEC 61131-3

5.1 Introduction

5.1.1 Weaknesses in Traditional PLCs

5.1.2 Improvements with IEC 61131-3

5.1.3 On Implementation of the Standard

5.2 Brief Presentation of the Languages

5.2.1 ST

5.2.2 FBD

5.2.3 LD

5.2.4 IL

5.2.5 SFC

5.3 Program Structure in IEC 61131-3

5.3.1 Example of a Configuration

5.4 Program Processing

5.4.1 Development of Programming Languages

5.4.2 From Source Code to Machine Code

5.5 Test Problems

Chapter 6 IEC 61131-3: Common Language Elements

6.1 Introduction

6.2 Identifiers, Keywords, and Comments

6.2.1 Identifiers

6.2.2 Keywords

6.2.3 Comments

6.3 About Variables and Data Types

6.4 Pragmas and Literals

6.4.1 Literal

6.5 Data Types

6.5.1 Numerical and Binary Data Types

6.5.2 Data Types for Time and Duration

6.5.3 Text Strings

6.5.4 Generic Data Types

6.5.5 User-Defined Data Types

6.6 Variables

6.6.1 Conventional Addressing

6.6.2 Declaration of Variables with IEC 61131-3

6.6.3 Local Versus Global Variables

6.6.4 Input and Output Variables

6.6.5 Other Variable Types

6.7 Direct Addressing

6.7.1 Addressing Structure

6.7.2 I/O-Addressing

6.8 Variable versus I/O-Addresses

6.8.1 Unspecified I/O-Addresses

6.9 Declaration of Multielement Variables

6.9.1 Arrays

6.9.2 Data Structures

6.10 Test Problems

Chapter 7 Functions

7.1 Introduction

7.2 On Functions

7.3 Standard Functions

7.3.1 Assignment

7.4 Boolean Operations

7.5 Arithmetic Functions

7.5.1 Overflow

7.6 Comparison

7.7 Numerical Operations

7.7.1 Priority of Execution

7.8 Selection

7.9 Type Conversion

7.10 Bit-String Functions

7.11 Text-String Functions

7.12 Defining New Functions

7.13 EN/ENO

7.14 Test Problems

Chapter 8 Function Blocks

8.1 Introduction

8.1.1 The Standard’s FBs

8.2 Declaring and Calling FBs

8.3 FBs for Flank Detection

8.4 Bistable Elements

8.5 Timers

8.6 Counters

8.6.1 Up-Counter

8.6.2 Down-Counter

8.6.3 Up/Down-Counter

8.7 Defining New FBs

8.7.1 Encapsulation of Code

8.7.2 Other Nonstandardized FBs

8.8 Programs

8.8.1 Program Calls

8.8.2 Execution Control

8.9 Test Problems

Part 4 Programming

Chapter 9 Ladder Diagram (LD)*

9.1 Introduction

9.2 Program Structure

9.2.1 Contacts and Conditions

9.2.2 Coils and Actions

9.2.3 Graphical Elements: An Overview

9.3 Boolean Operations

9.3.1 AND/OR-Conditions

9.3.2 Set/Reset Coils

9.3.3 Edge Detecting Contacts

9.3.4 Example: Control of a Mixing Process

9.4 Rules for Execution

9.4.1 One Output: Several Conditions

9.4.2 The Importance of the Order of Execution

9.5 Use of Standard Functions in LD

9.6 Development and Use of FBs in LD

9.7 Structured Programming in LD

9.7.1 Flowchart versus RS-Based LD Code

9.7.2 State Diagrams versus RS-Based LD Code

9.8 Summary

9.9 Test Problems

Chapter 10 Function Block Diagram (FBD)

10.1 Introduction

10.2 Program Structure

10.2.1 Concepts

10.3 Execution Order and Loops

10.3.1 Labels and Jumps

10.4 User-Defined Functions and FBs

10.5 Integer Division

10.6 Sequential Programming with FBD

10.7 Test Problems

Chapter 11 Structured Text (ST)

11.1 Introduction

11.2 ST in General

11.2.1 Program Structure

11.3 Standard Functions and Operators

11.3.1 Assignment

11.4 Calling FBs

11.4.1 Flank Detection and Memories

11.4.2 Timers

11.4.3 Counters

11.5 IF Statements

11.6 CASE Statements

11.7 ST Code Based upon State Diagrams

11.7.1 Example: Code for the Level Process

11.8 Loops

11.8.1 WHILE … DO… END_WHILE

11.8.2 FOR … END_FOR

11.8.3 REPEAT … END_REPEAT

11.8.4 The EXIT Instruction

11.9 Example: Defining and Calling Functions

11.10 Test Problems

Chapter 12 Sequential Function Chart (SFC)

12.1 Introduction

12.1.1 SFC in General

12.2 Structure and Graphics

12.2.1 Overview: Graphic Symbols

12.2.2 Alternative Branches

12.2.3 Parallel Branches

12.3 Steps

12.3.1 Step Addresses

12.3.2 SFC in Text Form (for Those Specially Interested…)

12.4 Transitions

12.4.1 Alternative Definition of Transitions

12.5 Actions

12.5.1 Action Types

12.5.2 Action Control

12.5.3 Alternative Declaration and Use of Actions

12.6 Control of Diagram Execution

12.7 Good Design Technique

12.8 Test Problems

Chapter 13 Examples

13.1 Example 1: PID Controller Function Block: Structured Text

13.2 Example 2: Sampling: SFC

13.2.1 List of Variables

13.2.2 Possible Solution

13.3 Example 3: Product Control: SFC

13.3.1 Functional Description

13.3.2 List of Variables

13.3.3 Possible Solution

13.4 Example 4: Automatic Feeder: ST/SFC/FBD

13.4.1 Planning and Structuring

13.4.2 Alternative 1: SFC

13.4.3 Alternative 2: ST/FBD

Part 5 Implementation

Chapter 14 CODESYS 2.3

14.1 Introduction

14.2 Starting the Program

14.2.1 The Contents of a Project

14.3 Configuring the (WAGO) PLC

14.4 Communications with the PLC

14.4.1 The Gateway Server

14.4.2 Local Connection via Service Cable

14.4.3 Via Ethernet

14.4.4 Communication with a PLC Connected to a Remote PC

14.4.5 Testing Communications

14.5 Libraries

14.6 Defining a POU

14.7 Programming in FBD/LD

14.7.1 Declaring Variables

14.7.2 Programming with FBD

14.7.3 Programming with LD

14.8 Configuring Tasks

14.9 Downloading and Testing Programs

14.9.1 Debugging

14.10 Global Variables and Special Data Types

Chapter 15 CODESYS Version 3.5

15.1 Starting a New Project

15.1.1 Device

15.1.2 Application

15.2 Programming and Programming Units (POUs)

15.2.1 Declaration of Variables

15.3 Compiling and Running the Project

15.3.1 Start Gateway Server and PLS and Set Up Communications

15.4 Test Problems

Bibliography

Index

EULA