Programmable Logic Controllers

Table of Contents

Chapter 1: Introduction to Programmable Logic Controllers

Topics: The electromagnetic relay; Characteristics of programmable controllers; Applications of programmable controllers; Limitations of programmable controllers; Parts of a programmable logic controller system; The input side; The processor; The output side; Programming devices; Power supplies

Learning Objectives:

• Describe an electromagnetic relay and define the terms control circuit, power circuit, NO and NC.
• Define programmable logic controller.
• Describe the general type of application in which a programmable logic controller would best be used, and give examples.
• Define scan time.
• Name each of the blocks in a block diagram of a programmable logic controller system and explain how each functions within the system as a whole.
• Define memory and explain the different types

Chapter 2: Number Systems and Logic

Topics: Number systems; Binary-Coded Decimal (BCD); ASCII; Gray code; Boolean logic; Ladder logic

Learning Objectives:

• Compare the decimal, binary, octal, and hexadecimal number systems.
• Explain the purpose for using each of the following: BCD, Gray code, and ASCII.
• Explain what AND, OR, and NOT mean in Boolean logic, and identify the symbols for each.
• Identify AND and OR logic circuits in a relay ladder diagram, and construct a truth table for each.
• Explain the basic concepts of ladder logic..

Chapter 3: Programming the System

Topics: PLC programming; Ladder logic programming; Boolean programming; The AND instruction The OR instruction; The stack register

Learning Objectives:

• Explain the relationship between a programmable logic controller processor and program.
• Define the term scan and explain the basic steps involved in a scan.
• Explain the basic concepts of ladder logic programming.
• Explain the purpose of a parallel branch in a ladder logic program.
• Explain the basic concepts of Boolean programming.
• Define stack register and state the stack rule.

Chapter 4: Input/Output Devices and Modules

Topics: Definition of I/O devices; Discrete input devices; Analog input devices; Digital input devices; Discrete output devices; Analog output devices; Digital output devices; Sourcing and sinking; Definition of I/O modules; Input modules; Output modules

Learning Objectives:

• Explain the operation of common input and output devices and identify their symbols.
• Describe the relationship of an input/output device to a terminal on an input/output module.
• Contrast the basic concepts of a sourcing device and a sinking device.
• Explain the operation of various input and output modules.

Chapter 5: Developing a Programmable Logic Controller System

Topics: Before you begin; Equipment operation specifications; Sizing the system; Program development; Assembling the documentation package; Functional model; Startup and debugging

Learning Objectives:

• Explain the importance of working with accurate information from a specification.
• Demonstrate how to size a system.
• List the elements in a good documentation package.
• Name the steps involved in specifying the hardware and developing the program for a simple control system.
• Describe system startup and debugging procedures.

Chapter 6: Maintenance and Troubleshooting

Topics: The importance of documentation in maintenance troubleshooting; Using the hardware documentation; The maintenance log; Using the program documentation; Operational documentation; Routine maintenance; Batteries; Troubleshooting; Problems in troubleshooting; Troubleshooting in practice

Learning Objectives:

• Explain the importance of good documentation.
• Tell what type of information can be found in user manuals and operations manuals.
• Tell what types of logs are kept and why they are necessary.
• Explain the major concepts of troubleshooting, including problems sometimes encountered.
• Describe routine maintenance procedures required by a programmable controller system.

Chapter 7: System Expansion and Data Networks

Topics: I/O expansion; Configuring the system; Math and data handling instructions; Timers and counters; The shift register; Spray booth retrofit; Indexing table retrofit; Local area networks; Uses for LANs; Transmission media; Transmission schemes; Vendor offerings

Learning Objectives:

• Compare the procedures involved in local and remote I/O expansion.
• Explain what is meant by configuring a system.
• Describe the operation of the shift register instruction.
• Explain how math and data-handling instructions work and why they are added to PLC systems.
• List important items to consider in I/O expansion and retrofitting.
• Define the terms local area network, baud rate, and throughput.
• List and explain the contents of a data packet used in LAN data transmission.
• Name and define the three main applications of LANs.
• List advantages and disadvantages of the three common transmission media used with LANs.

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