Programmable Logic Applications and Devices and Lab

Course Description

Programmable Logic Applications and Devices and Lab develops the logic fundamentals underlying programmable logic controllers and the practical ability to program them — binary data representation and base conversion, Boolean logic, ladder diagrams, and the control of relays, sensors, actuators, and industrial devices as PLC inputs and outputs.

Within the SCNS taxonomy, ETS is the Engineering Technology: Specialized prefix, and the 3000-level number places this in the upper division of a baccalaureate in engineering technology. Daytona State publishes it at 3 credits with a $10 lab fee, prerequisite MAC1105, offered fall, spring, and summer. The C suffix marks a combined lecture-and-laboratory format, giving approximately 60 contact hours.

PLCs are the reason modern manufacturing works. They are industrial computers built to survive heat, vibration, and electrical noise, and they run essentially every automated process in a plant — conveyors, packaging lines, water treatment, HVAC, amusement rides, and bottling. The skill is durable in a way few software skills are: the ladder logic in service today would be legible to a technician trained thirty years ago, and the installed base is enormous.

⚠ Number, suffix, and level: three separate traps on one course

This course sits at the intersection of every numbering hazard this repository documents, so check carefully before assuming anything transfers.

1. The C suffix. This repository also carries ETS3543 — the same number without the C — published at 4 credits and approximately 80 contact hours. The suffix is part of the number, and here it comes with a full credit's difference. The two are not interchangeable.

2. The level. Broward College teaches essentially this subject as ETS2542C Programmable Logic Controllers, 3 credits, 64 contact hours (48 lecture + 16 lab) — a 2000-level course inside an A.S. programme. This course is 3000-level. Lower-division credit generally cannot satisfy an upper-division requirement, so ETS2542C will not substitute for ETS3543C in a baccalaureate even though the content overlaps heavily. This is the 2000-to-3000 boundary that matters, and PLC coursework is one of the places students hit it hardest.

3. The family sprawl. Florida teaches PLC content under at least five distinct numbers with different credit values:

Number	Title	Credits / hours
ETS1542C	Introduction to PLCs	3 / 60
ETS2542C	Introduction to Programmable Logic Controllers	3 / 60–64
ETS2544C	Advanced PLCs	2 / 60
ETS2673C	Programmable Logic Controls	4 / 80
ETS3543C	this course	3 / 60
ETS3543	Programmable Logic Controllers	4 / 80

Sequence by number and prerequisite chain, never by title. Have any substitution evaluated in writing.

Learning Outcomes

Required Outcomes

• Describe PLC architecture: processor, memory, power supply, and I/O modules.
• Convert among binary, decimal, hexadecimal, and BCD representations.
• Apply Boolean algebra and construct and simplify logic expressions.
• Relate Boolean logic to relay logic and to ladder diagram rungs.
• Read and interpret ladder logic diagrams.
• Describe the PLC scan cycle and its implications for program behaviour.
• Identify discrete and analog input and output devices and their wiring requirements.
• Wire sensors, switches, relays, contactors, and actuators to PLC I/O correctly.
• Assign and document I/O addressing for a control system.
• Program basic instructions: examine-if-closed, examine-if-open, and output energize.
• Program timers and counters and apply them to real control sequences.
• Program comparison, math, and data-handling instructions.
• Implement latching, sealing, and interlocking logic.
• Program a sequential process control application.
• Handle analog signals, including scaling and resolution.
• Troubleshoot a PLC system systematically, distinguishing field device, wiring, and program faults.
• Use programming software to monitor, force, and edit online, and describe the hazards of doing so.
• Document a control program so another technician can maintain it.
• Apply electrical safety and lockout/tagout practice in an industrial control environment.

Optional Outcomes

• Describe industrial networks and fieldbus protocols.
• Configure and use an HMI with a PLC program.
• Describe SCADA architecture and its relationship to PLCs.
• Apply PID control loops in a PLC.
• Describe safety PLCs, safety relays, and functional safety concepts.
• Describe variable frequency drive integration.
• Describe industrial control system cybersecurity at an introductory level.

Major Topics

Required Topics

• PLC architecture and hardware
• Number systems: binary, decimal, hexadecimal, BCD
• Boolean algebra and logic simplification
• Relay logic and its translation to ladder diagrams
• Ladder logic reading and construction
• The scan cycle
• Discrete and analog I/O devices
• Field wiring: sensors, relays, contactors, actuators
• I/O addressing and documentation
• Basic instruction set
• Timers and counters
• Comparison, math, and data handling
• Latching, sealing, and interlocks
• Sequential process control
• Analog signal handling and scaling
• Systematic troubleshooting
• Online monitoring, forcing, and editing
• Program documentation
• Electrical safety and lockout/tagout

Optional Topics

• Industrial networks and fieldbus
• HMI configuration
• SCADA systems
• PID control
• Safety PLCs and functional safety
• Variable frequency drives
• ICS cybersecurity

Resources & Tools

• Programmable Logic Controllers (Petruzella) — the standard text in this course across the country.
• Automating Manufacturing Systems with PLCs (Hugh Jack) — free and open, thorough, and unusually good on the logic fundamentals.
• Rockwell Automation / Allen-Bradley — the dominant platform in North American industry. Studio 5000 Logix Emulate and the free Connected Components Workbench for Micro800 controllers let you practise without hardware.
• Siemens TIA Portal — the dominant platform in Europe and common in Florida's international-equipment plants; a free trial and a student edition are available.
• Automation Direct — free software downloads, inexpensive hardware, and excellent free documentation; the cheapest way to own a real PLC.
• OpenPLC — free, open-source, runs on a Raspberry Pi, and follows IEC 61131-3. A genuinely usable home lab for under fifty dollars.
• NFPA 70E — electrical safety in the workplace; the standard governing arc flash and energized work.
• OSHA 29 CFR 1910.147 — the lockout/tagout standard, free to read and directly examinable.
• IEC 61131-3 — the standard defining the PLC programming languages, including ladder, structured text, and function block.
• PLCTalk forums and the manufacturers' knowledge bases — where practising technicians actually solve problems.

Career Pathways

• Automation technician and controls technician — the direct destination, and consistently in short supply.
• Controls engineer — designing and commissioning control systems; the upper-division degree is what opens this title.
• Maintenance technician, industrial — manufacturing, food and beverage, packaging, and pharmaceuticals.
• Systems integrator — firms that build and commission automated systems for clients; varied work and good pay.
• Water and wastewater automation — Florida's utilities run extensive SCADA and PLC infrastructure, and these are stable public-sector roles.
• Theme park and attractions controls — a genuinely large and Florida-specific employer of controls technicians, with demanding safety requirements.
• Aerospace and space launch — ground support equipment and test systems on Florida's Space Coast.
• Field service engineer — equipment manufacturers employ travelling commissioning and support staff.
• Industrial control system cybersecurity — an emerging, well-paid specialization for people who understand both the process and the network.
• SOC codes 17-3023 Electrical and Electronic Engineering Technologists and Technicians, 49-2094 Electrical and Electronics Repairers, Commercial and Industrial Equipment, and 17-2112 Industrial Engineers for the engineering track.

Special Information

⚠ The scan cycle explains most PLC behaviour that surprises beginners

The concept that separates students who can write ladder logic from students who can debug it.

A PLC does not execute continuously; it scans. Every cycle it reads all inputs into an image table, executes the program from top to bottom and left to right, then writes all outputs at once, then repeats — typically in a few milliseconds. Almost every counterintuitive behaviour in a PLC program follows from that:

• Rung order matters. An output energized on rung 3 and de-energized on rung 12 will simply be off, because the later rung wins in the same scan. Beginners write contradictory logic and blame the controller.
• Inputs are sampled, not watched. A pulse shorter than the scan time can be missed entirely — which is exactly why high-speed counter inputs and interrupt instructions exist.
• Outputs change only at the end of the scan, so an output set mid-program does not physically actuate until the write phase.
• Scan time varies with program length and branching, and a long scan degrades the responsiveness of everything.
• Timers are updated on the scan, which is why timer resolution and scan time interact.

The debugging habit that follows: watch the logic online, in real time, with the software's animation on. Seeing which contacts are true during an actual scan resolves in seconds what reading the printout will not resolve at all.

⚠ Safety: this is control of machinery that can kill, and the standards are not advisory

The most important content in the course, and the reason PLC work carries real professional responsibility.

A PLC output starts a motor. The program you write moves conveyors, closes presses, opens valves, and energizes drives — around people. Two categories of hazard follow, and they need different treatment.

Electrical hazard, to you:

• Lockout/tagout (OSHA 29 CFR 1910.147) is mandatory before working on equipment. A PLC in "program" mode is not a safe state, and neither is a stopped machine — stopped is not de-energized.
• Arc flash is the industrial electrical hazard that maims, and NFPA 70E governs it: risk assessment, boundaries, and arc-rated PPE. Control panels at industrial voltages are not benign because the logic is low voltage.
• Verify absence of voltage with a meter you have just tested on a known source. Assumption is the mechanism of most electrical injuries.
• Stored energy — capacitors in drives, pneumatic and hydraulic pressure, suspended loads, and springs — remains after power is removed.

Machine safety, to everyone else:

• Safety functions must not depend on standard PLC logic. Emergency stops, light curtains, and interlocks are implemented in hardwired safety circuits or rated safety PLCs and safety relays precisely because an ordinary controller can fail, be modified, or be bypassed. Writing an e-stop as a normal rung is a serious design error.
• Fail-safe design — wire safety devices so a broken wire or lost power produces the safe state, not the running one. This is why e-stops use normally-closed contacts.
• Forcing an I/O point overrides reality and is genuinely dangerous on live equipment. Force only with the machine secured, tell everyone, document it, and remove forces before leaving. Forces left in place have caused fatalities.
• Online editing changes a running machine. Understand exactly what the edit does before accepting it.

The professional stance worth adopting now: before energizing anything, ask what happens if this program is wrong. That question, asked routinely, is what separates a controls professional from someone who can write ladder logic.

⚠ Documentation is the deliverable, and undocumented logic is a liability

Underrated in coursework, decisive in employment.

PLC programs outlive the people who write them. A machine installed today may run for twenty-five years, and at 2am someone who has never met you will open your program with the line down and production stopped. What that person needs:

• Symbolic tag names that say what the device is — Conveyor_2_Run, not B3:0/7.
• Rung comments explaining intent, not restating the instruction. "Seals in run command until stop or fault" is useful; "XIC B3:0/1" is not.
• An accurate I/O list matching the panel drawings and the field labels.
• A record of the sequence of operations in plain language, which is often the only description of what the machine is supposed to do.
• Version control and a backup of the last known good program, stored somewhere other than the laptop that was in the shop.

The blunt career point: a technician who documents well gets called for the good jobs. Integrators and plants both know exactly what undocumented code costs them.

⚠ Build a home lab — it is cheap now and it is what gets you hired

Concrete and high-return advice for an upper-division student.

PLC skill is hands-on and demonstrable, and the barrier to practising at home has collapsed:

• OpenPLC on a Raspberry Pi — free software, IEC 61131-3 compliant, total cost under fifty dollars.
• Automation Direct CLICK or Productivity series — real industrial PLCs at low cost, with free programming software and good documentation.
• Rockwell's Connected Components Workbench is free for Micro800 controllers, and Logix Emulate lets you run Studio 5000 logic without a processor.
• Siemens offers a student edition of TIA Portal with simulation.
• Simulation software such as Factory I/O lets you drive a simulated plant from real logic — a genuinely good way to practise sequential control.

What to do with it: build something with a real sequence — a traffic light, a bottling line, a lift — and document it properly. A candidate who arrives with a working, well-commented project and can explain their fault-handling logic is answering the interview question before it is asked.

The complementary credential worth knowing about: industry certifications from Rockwell and Siemens are recognized and sometimes employer-funded, and for the maintenance track the ISA Certified Control Systems Technician (CCST) is well regarded.

Course format and transfer

ETS3543C is 3 credits with an estimated 60 contact hours and a $10 lab fee. The C suffix means combined lecture and laboratory instruction, and the lab is the substance: expect graded programming and wiring practicals, troubleshooting exercises where a fault is introduced and must be found, and a sequential control project. Written assessment covers number systems, Boolean logic, and scan behaviour.

How Florida course levels affect transfer

The first digit of an SCNS number denotes the year of offering, not transferability. Courses at the 1000 and 2000 levels transfer transparently between Florida public institutions, and 3000 to 4000 is unproblematic since both are upper division. The boundary that actually matters is 2000 to 3000, where lower-division credit generally cannot satisfy an upper-division requirement.

Transfer requires unusual care here for the three reasons set out above — the C suffix, the 2000-versus-3000 level, and the five-number family. In particular, an A.S. graduate holding ETS2542C should expect to take this course rather than receive credit for it, and should confirm that expectation in writing with the receiving programme rather than discovering it at graduation audit. Note also that A.S. degrees are applied and do not carry the A.A.'s guaranteed junior-status transfer, though Florida institutions publish specific B.S. in Engineering Technology articulation pathways for exactly this population.