PLC Simulator
Free for students

PLC Simulator for Students

Practice real IEC 61131-3 ladder logic in your browser. Auto-graded machine scenarios, structured lessons, and interview preparation — no install, no credit card.

Start freeLearning roadmap →

Join 1300+ learners practicing PLC programming

Create a free account to track progress. 2 auto-graded scenarios free forever.

Why students choose us

Everything you need. Zero hardware cost.

Real IEC 61131-3 execution

Your ladder logic runs through a real parser and interpreter — not a visualisation. The same IEC standard used in Codesys, OpenPLC, and hundreds of industrial controllers.

Auto-graded feedback

Each of the 40 machine scenarios has a hidden test suite. Submit your program and get objective, instant feedback — no need to ask someone to check your work.

Structured curriculum

18 lessons, 12 quizzes, 6 interview tracks. The curriculum takes you from PLC fundamentals to PID control to job-ready in a single continuous path.

The concepts you'll learn

A visual map of the PLC fundamentals

The 18-lesson curriculum builds these core concepts in order — from how a PLC scans, to ladder logic, to timers and counters, to structured text. Every diagram below is something you will write and run yourself in the browser, then be auto-graded on. No hardware, no install, no credit card.

PLC architecture for students — CPU, input modules, output modules and field devices — the first concept in the free PLC curriculumA modular PLC rack on a backplane: power supply, CPU processor, input module, output module and a communications module side by side.PLC RACKbackplane busPSUPowerCPUProcessorDIInputDOOutputNETComms
Lesson 1 — what a PLC is: CPU, inputs, outputs, and the field devices they connect to.
The PLC scan cycle for students — read inputs, execute the program, update outputs, then repeat — taught early in the free browser PLC curriculumThe repeating PLC scan cycle: read inputs, execute the ladder logic, update outputs, then housekeeping, looping continuously.1Read Inputs2Execute Logic3Update Outputs4HousekeepingSCANCYCLE
The scan cycle — the single idea that makes ladder logic make sense.
A student's first ladder logic rung — a normally-open contact driving an output coil — written and auto-graded in the browser PLC simulatorA basic ladder logic rung between two power rails: an examine-if-closed contact (XIC) in series driving an output coil (OTE).L1L2] [StartXIC I:0/0LampOTE O:0/0
Your first rung — a contact driving a coil — graded instantly in the browser.
Ladder logic symbols for students — normally-open and normally-closed contacts, output coils, set and reset coils — the alphabet of PLC programmingThe core ladder logic symbols side by side: XIC examine-if-closed, XIO examine-if-open, OTE output energize, OTL output latch and OTU output unlatch.XICIfXIOIfOTEEnergizeLOTLLatchUOTUUnlatch
The ladder symbol set — the alphabet you read and write across every scenario.
An IEC TON on-delay timer timing chart for students, the instruction behind the traffic-light scenario in the free PLC curriculumA TON on-delay timer: the accumulated time bar ramps up toward the preset value, and the done (DN) bit turns on when the accumulator reaches preset.TONPRE 5000ACCACC ramps to PREPREDNdone bit
Timers (TON / TOF) — the instruction behind the traffic-light scenario.
An IEC CTU up-counter for students, the instruction used to count parts in the conveyor-sort scenario of the free PLC curriculumA CTU count-up counter: each input pulse increments the accumulator toward the preset, and the done (DN) bit turns on when count reaches preset.count pulsesCTUPRE 5ACC 3ACCcount toward presetDNdone bit
Counters (CTU / CTD) — the instruction used to count parts in conveyor scenarios.
The five IEC 61131-3 languages for students — Ladder, Function Block, Structured Text, SFC and Instruction List — the standard taught in the free PLC curriculumThe five IEC 61131-3 PLC programming languages as chips: Ladder Diagram, Function Block Diagram, Structured Text, Instruction List and Sequential Function Chart.IEC 61131-3 — five languagesLDLadder DiagramFBDFunction BlockSTStructured TextILInstruction ListSFCSequential Func. Chart
IEC 61131-3 — the international standard, so the skills transfer to Codesys, OpenPLC and real controllers.
An IEC 61131-3 Structured Text code block for students, the text-based PLC language introduced later in the free curriculum for state machines and PIDA small Structured Text code block in an editor: an IF/THEN condition, a TON timer call and assignments, showing text-based PLC programming.main.st — Structured Text1IF Start AND NOT Stop THEN2 Run := TRUE;3END_IF;4DelayTmr(IN := Run, PT := T#5s);5Lamp := DelayTmr.Q;
Structured Text — the high-level language for state machines and PID, introduced later in the path.

Follow it all in the free 18-lesson curriculum, or jump straight into the browser PLC simulator.

Practice scenarios

From traffic lights to industrial machines

40 scenarios across 6 verticals. Each scenario has a detailed brief, animated simulation, and auto-graded test cases.

Beginner

Traffic Light

Three-phase timer sequence. Classic first PLC project.

View scenario →
Beginner

Motor Start/Stop

Seal-in rung, stop button, overload protection.

View scenario →
Intermediate

Tank Fill

Level sensor, inlet valve, pump, overflow alarm.

View scenario →
Advanced

PID Temperature

Closed-loop temperature control with PID tuning.

View scenario →
See all 40 scenarios →

How it works

Four steps to your first passing program

01

Sign up free

Create your account in 30 seconds. No credit card. Two auto-graded scenarios unlocked immediately.

02

Start the curriculum

Follow the 18-lesson structured path from PLC fundamentals to PID control, or go straight to a scenario.

03

Write real programs

Type ladder logic or structured text in the code editor. Run it against the machine simulation and watch outputs respond in real time.

04

Get graded feedback

Submit your program and the auto-grader runs every test case. See exactly which steps passed and which failed.

Why us

vs OpenPLC, LogixPro, and PLC-Fiddle

No install — works on any browser, any OS, any device
Auto-graded scenarios give objective pass/fail feedback
Structured 18-lesson curriculum vs no guided path
Three vendor dialects: IEC, Allen-Bradley, Siemens
Interview tracks with timed coding rounds
Free forever tier — not a 30-day trial

Pricing

Start free. Go pro when you are ready.

The free tier gives you 2 scenarios and access to the first lesson — enough to know if the platform works for you. Full access to all 40 scenarios, 18 lessons, 12 quizzes, and 6 interview tracks is available at a monthly or annual rate.

Start freeSee pricing
Questions

Student FAQ

Yes. The free tier gives you 2 fully auto-graded scenarios — Traffic Light and Motor Start/Stop — with no credit card required and no time limit. You can return to them as many times as you like. Upgrade to access all 40 scenarios when you are ready.

Start learning PLC programming today

Free tier. No install. No credit card. 30-second signup.

Create free account →