PLC Diagrams and Programs 300

This class will teach you how to convert line diagrams and wiring diagrams for use with PLCs.

  • Difficulty Advanced

  • Format Online

  • Number of Lessons 12

  • Language English


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Course Outline
  • Objectives
  • Using Diagrams
  • Line Diagrams
  • PLC Line Diagrams
  • Developing Programs
  • Programming Diagrams
  • Rules For Programming
  • Entering Programs
  • Wiring Diagrams
  • PLC Wiring Diagrams
  • Using PLC Wiring Diagrams
  • Summary
  • Describe diagrams used for PLCs.
  • Describe line diagrams.
  • Distinguish between hardwired and PLC line diagrams.
  • Describe how PLC programs are developed.
  • Describe PLC programming diagrams.
  • Describe rules for PLC programming.
  • Describe how programs are entered into a PLC.
  • Describe wiring diagrams.
  • Distinguish between hardwired and PLC wiring diagrams.
  • Describe how PLC wiring diagrams are used.
Vocabulary Term

examine if closed

A basic PLC input instruction that updates the output if the contact switches from open to closed.

examine if open

A basic PLC input instruction that updates the output if the contact switches from closed to open.

handheld programmer

A PLC programming device that combines a display screen and keypad all in one unit. Specially assigned keys allow you to enter program instructions, changes, and navigate and troubleshoot the PLC system.

ladder logic

The most common programming language for PLCs. Ladder logic is based on line diagrams.

line diagram

A diagram that shows the logic of an electrical circuit using standard symbols. Also known as a ladder diagram because the diagram appears as individual lines or "rungs" connected between two vertical lines, line diagrams can be converted into PLC ladder logic.


The sequence of operations performed by a circuit or the sequence of instructions performed by a PLC.

memory circuit

A type of circuit that stores a charge and keeps the load energized even after the signal is removed.

PLC wiring diagram

A diagram that shows the locations that inputs and outputs are physically connected to PLC terminals. The physical locations do not directly affect the circuit logic.


The main device that processes information and carries out instructions in a PLC. Also known as the CPU or controller.

programmable logic controller

A processor driven device that uses logic-based software to provide electrical control to machines.

programming diagram

A type of line diagram that uses the input and output symbols used by PLC ladder logic. Line diagrams are converted to programming diagrams before being entered into a PLC.


One of multiple horizontal programming lines in a ladder logic diagram. Each rung controls one output.


A connecting point on PLC input and output modules to which a wire can be attached to connect a component.


A method by which a problem is solved. Troubleshooting a PLC often involves using the prints as a guide to find the problem area.

wiring diagram

The most detailed of electrical prints. A wiring diagram shows the physical relationship of all the components, as well as the information needed to hardwire the circuit.