Introduction to PLCs (Programmable Logic Controllers)

Course Description

This course introduces students to the fundamental theory and application of Programmable Logic Controllers (PLCs) in industrial automation environments. Topics include ladder logic programming, PLC hardware architecture, input/output (I/O) system configuration, memory addressing, and the design, application, and troubleshooting of PLC-based control systems. The course integrates class instruction with hands-on laboratory experiments, simulation trainers, and multi-modal software learning labs to replicate real-world industrial conditions. This is a combined lecture and laboratory course (as indicated by the "C" lab designator in the Florida SCNS).

This course is part of the Engineering Technologies > Specialty Engineering Technology taxonomy within Florida's Statewide Course Numbering System (SCNS).

Learning Outcomes

Required Outcomes

Upon successful completion of this course, students will be able to:

• Explain the fundamental theory and operation of a Programmable Logic Controller (PLC), including CPU operation, memory organization, and the scan cycle.
• Identify and describe PLC hardware components, including power supplies, processors, input/output (I/O) modules, and communication ports.
• Interpret and construct ladder logic diagrams using basic instructions such as examine-if-closed (XIC), examine-if-open (XIO), and output energize (OTE).
• Configure and connect discrete digital input and output devices to a PLC system.
• Program and apply timer and counter instructions to solve industrial control problems.
• Use PLC programming software to enter, edit, download, and monitor ladder logic programs on a hardware or simulated PLC.
• Apply systematic troubleshooting techniques to diagnose and correct faults in PLC-based control systems.
• Demonstrate safe work practices when wiring, operating, and maintaining PLC systems in a laboratory environment.

Optional Outcomes

Depending on the institution and program focus, students may also be able to:

• Program and apply data manipulation instructions such as move, compare, and arithmetic operations.
• Configure and interpret analog input and output modules using standard 4–20 mA and 0–10 VDC signal ranges.
• Demonstrate basic programming using alternative IEC 61131-3 languages such as Structured Text (ST) or Function Block Diagram (FBD).
• Interface a PLC with a Human-Machine Interface (HMI) for basic operator display and control.
• Configure basic industrial communication networks such as DeviceNet, EtherNet/IP, or Modbus.
• Apply PLC programming techniques to control Variable Frequency Drives (VFDs) for motor speed regulation.

Major Topics

Required Topics

1. Introduction to Industrial Automation and PLCs
   • History and evolution of PLCs vs. relay-based control
   • Overview of PLC manufacturers (Rockwell/Allen-Bradley, Siemens, Omron)
   • PLC classifications: micro, small, medium, and large systems
2. PLC Hardware Architecture
   • CPU, memory types (RAM, ROM, EEPROM), and the scan cycle
   • Power supply selection and installation
   • Discrete digital I/O modules: sourcing and sinking configurations
   • I/O addressing and memory mapping
3. Ladder Logic Fundamentals
   • Rung structure, rails, and program organization
   • Bit instructions: XIC, XIO, OTE, OTL, OTU
   • Normally open and normally closed contacts
   • Seal-in (latch) circuits and interlock logic
4. Timer and Counter Instructions
   • Timer-On Delay (TON), Timer-Off Delay (TOF), Retentive Timer (RTO)
   • Count-Up (CTU), Count-Down (CTD) instructions
   • Preset values, accumulated values, and status bits
5. PLC Programming Software and Simulation
   • Introduction to RSLogix 500/Micro Starter Lite or equivalent platform software
   • Creating, downloading, and monitoring a ladder logic program
   • Using simulation tools for program testing without hardware
6. Input/Output Wiring and Device Interfacing
   • Wiring pushbuttons, limit switches, proximity sensors, and pilot lights
   • Surge protection and grounding practices
   • Selection and installation of I/O field devices
7. Troubleshooting PLC-Based Systems
   • Fault indicators and status LEDs
   • Online monitoring and forcing I/O points
   • Systematic diagnostic procedures and documentation
8. Safety in PLC Environments
   • Electrical safety, lockout/tagout (LOTO) procedures
   • NEC and NFPA 79 standards overview for industrial control panels

Optional Topics

• Data Manipulation Instructions: MOV, arithmetic (ADD, SUB, MUL, DIV), and comparison instructions (EQU, GRT, LES)
• Analog I/O: Configuration of 4–20 mA and 0–10 VDC modules; scaling analog signals in ladder logic
• Alternative IEC 61131-3 Programming Languages: Introduction to Structured Text (ST) and Function Block Diagram (FBD)
• Human-Machine Interface (HMI) Integration: Basic HMI screen design and PLC data communication
• Industrial Networking: Introduction to EtherNet/IP, DeviceNet, and Modbus protocols
• Variable Frequency Drives (VFDs): PLC-controlled motor speed and direction using VFD parameter configuration
• Sequential Function Charts (SFC): Introduction to state-based and step-sequence programming

Resources & Tools

• Programming Software: RSLogix Micro Starter Lite / RSLogix 500 (Allen-Bradley), Studio 5000 / Connected Components Workbench (Rockwell Automation), or equivalent PLC software platform
• Simulation Software: RSLogix Emulate 500, Online PLC Simulator (plcsimulator.online), or equivalent ladder logic simulation environment
• Hardware Trainers: Allen-Bradley MicroLogix 1000/1100 or CompactLogix trainer stations; Siemens S7-1200 trainer kits (institution-dependent)
• Recommended Textbook: Programmable Logic Controllers by Frank Petruzella (McGraw-Hill); Introduction to PLCs by Gary Dunning
• Reference Standards: IEC 61131-3 (PLC Programming Languages Standard); NFPA 79 (Electrical Standard for Industrial Machinery); NEC Article 409 (Industrial Control Panels)
• Online Resources: Rockwell Automation Training (ra.rockwellautomation.com), PLC Academy (plcacademy.com), SolisPLC tutorials (solisplc.com)

Career Pathways

Completion of this course supports entry into and advancement within the following career fields:

• PLC Technician / Controls Technician – Programs, maintains, and troubleshoots PLC systems in manufacturing and process industries
• Industrial Maintenance Technician – Maintains automated manufacturing equipment including PLC-controlled machinery
• Automation Engineer Technologist – Designs and implements automated control solutions using PLCs and related hardware
• Instrumentation and Controls Technician – Configures and maintains process control instrumentation interfaced with PLCs
• Electrical Technician (Industrial) – Installs and services industrial electrical systems including PLC control panels

This course supports progression toward an Associate in Science (A.S.) degree in Engineering Technology, Electronics Technology, or Industrial Automation, as well as industry certifications in automation and controls.

Special Information

Certification Preparation: This course provides foundational preparation for the following industry-recognized credentials:

• Rockwell Automation Certified Technician (RACT) – Entry-level certification validating skills in Allen-Bradley PLC programming and maintenance
• NIMS Mechatronics Credentials – National Institute for Metalworking Skills credentials in programmable control systems
• ISA Certified Automation Professional (CAP) – Foundation knowledge applicable to the ISA CAP examination pathway
• Florida Department of Education (FLDOE) Industry Certifications: This course may contribute to stackable credentials recognized under Florida's Career and Technical Education (CTE) frameworks for Engineering Technology programs.

Lab Requirement: The "C" designator in ETS1542C indicates this is a combined lecture and laboratory course. Students are required to complete hands-on laboratory activities as an integral part of the course. Lab sessions involve live PLC hardware, simulation trainers, and wiring exercises. Appropriate safety attire and adherence to laboratory safety protocols are required at all times.