Description

Understanding PLCs in Marine Applications 

Programmable Logic Controllers (PLCs) play a critical role in a wide range of marine systems, including propulsion, safety, data acquisition, and motor control. To ensure these systems remain safe, reliable, and fully operational, marine engineers and Electro-Technical Officers (ETOs) must develop a solid understanding of PLC technology and troubleshooting techniques. 

This book supports that learning by explaining common onboard applications and promoting a systematic approach to fault diagnosis—helping engineers respond effectively to the many troubleshooting scenarios they may encounter. 

This publication is ideal for: 

• Management and operational level marine engineers 

• ETOs and shipboard electricians 

• Engineering and electrical cadets 

• Anyone beginning work with PLC-based marine systems 

Contents:

1. PLC Basics

1.1 Introduction 

1.2 Power Supply Modules 

1.3 The Input and Output (I/O) Interface 

1.4 PLC-based Application Terminology 

2. Inputs

2.1 Sinking and Sourcing Input 

2.2 Discrete Inputs (DI) 

2.3 Input Designations 

2.4 Discrete Inputs Interface Devices 

2.5 Wiring Discrete Inputs 

2.6 Analogue Inputs 

2.7 Inputs Expansion Modules 

3. Process Monitoring Analogue Sensors

3.1 Pressure Transducers 

3.2 Resistance Temperature Detectors 

3.3 NTC Thermistors 

3.4 Thermocouples (TC) 

3.5 Proximity Sensors 

3.6 Feedback Potentiometers 

3.7 AC Current Measuring Transducer 

3.8 Analogue-to-Discrete Converters 

3.9 Safety Stop Relays 

3.10 Analogue-to-Analogue Signal Converters 

4. Outputs

4.1 Definition 

4.2 Protecting PLC Output Transistors 

4.3 PLC Discrete I/O Status Display 

4.4 Analogue Outputs 

5. Flowcharts

5.1 Definition 

6. Numbering Systems and Conversions

6.1 The Decimal System 

6.2 The Binary System 

6.3 The Octal System 

6.4 The Hexadecimal (Hex) Numbering System 

6.5 The Binary Coded Decimal 

7. Ladder Logic

7.1 Definition 

7.2 Relay Function 

7.3 Impulse Relay Function 

7.4 Latching Relay Function 

8. Function Blocks

8.1 Definition 

8.2 Logic Gates 

9. PLC-based Direct-on-Line Motor Starter

9.1 Counter and Timer Instructions 

10. PLC-based Star-Delta Motor Starter

10.1 Star-delta Motor Starter Ladder Logic and Function Blocks 

10.2 Star-delta Reversing Motor Starter LAD and FBD Program 

11. PLC Communication and Networking

12. Troubleshooting PLC-based Applications

12.1 Troubleshooting PLC-based Applications 

12.2 PLC Application Troubleshooting 

12.3 PLC-based Application Troubleshooting Tips