PLC Simulator
CODESYS / IEC 61131-3

CODESYS Download Guide

CODESYS is the industry-reference IEC 61131-3 IDE — and the Development System is genuinely free. This guide covers the complete download path, SoftPLC demo mode (including the 2-hour limit), system requirements, vendor-specific device setup, and when a browser-based simulator gets you practising faster than a local install.

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CODESYS download guide — free IDE, SoftPLC demo mode, IEC 61131-3 practice

Overview

What is CODESYS?

CODESYS (Controller Development System) is an IEC 61131-3 development environment produced by 3S-Smart Software Solutions GmbH. Unlike Rockwell Studio 5000 or Siemens TIA Portal, CODESYS is not tied to a single hardware vendor — it is a platform that hardware manufacturers embed in their PLCs. The IDE you use to program a Wago PLC, a Beckhoff controller, and a Phoenix Contact PLCnext is the same CODESYS IDE.

This multi-vendor architecture is why learning CODESYS is unusually transferable. The five IEC 61131-3 languages — Ladder Diagram (LD), Function Block Diagram (FBD), Structured Text (ST), Instruction List (IL), and Sequential Function Chart (SFC) — behave identically across all CODESYS-based hardware, with only vendor-specific library extensions varying.

The five IEC 61131-3 languages CODESYS supports — Ladder Diagram, Function Block Diagram, Structured Text, Instruction List and Sequential Function ChartThe 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
CODESYS implements all five IEC 61131-3 languages — the same standard languages whichever vendor's hardware you target.
CODESYS PLC architecture — CPU scanning inputs and outputs, the model the CODESYS Control Win SL SoftPLC runtime emulates on your PCA modular PLC rack on a backplane: power supply, CPU processor, input module, output module and a communications module side by side.PLC RACKbackplane busPSUPowerCPUProcessorDIInputDOOutputNETComms
The PLC model CODESYS programs: a CPU running your IEC 61131-3 program against input and output modules — emulated in software by the CODESYS Control Win SL SoftPLC.
CODESYS IDEFree to downloadBeckhoffTwinCAT 3Wagoe!COCKPITPhoenix ContactPLCnext EngineerBosch RexrothctrlX WorksSchneiderMachine ExpertRaspberry PiCODESYS runtimeSame IDE — one standard, 400+ hardware products, 100+ vendors
CODESYS IDE programs hardware from Beckhoff, Wago, Phoenix Contact, Bosch Rexroth, Schneider, and dozens more — one IDE, vendor-neutral skills.

Free vs paid

What is free and what costs money

Free — no time limit

  • CODESYS Development System IDE (latest V3.5)
  • Write, compile, and build programs in all 5 IEC 61131-3 languages
  • Standard library function blocks (timers, counters, math, string)
  • CODESYS Store access for device description files
  • CODESYS Forge community plugins and extensions
  • Syntax checking, cross-reference, online help

Paid or limited

  • CODESYS Control Win SL (SoftPLC) — free in demo mode, stops after 2 hours
  • CODESYS Control for Linux SL — paid runtime license for Linux deployment
  • CODESYS Safety SIL — paid add-on for safety-rated programming
  • CODESYS Visualization (HMI) Web Client — paid for production deployment
  • CODESYS Motion CNC — paid add-on
  • Most vendor-specific hardware device profiles — included with hardware purchase

Requirements

System requirements for CODESYS V3.5

Operating systemWindows 10 (64-bit) or Windows 11 for the IDE. CODESYS Control Win SL for SoftPLC also runs on Windows.
RAM4 GB minimum; 8 GB recommended for running IDE + SoftPLC simultaneously
Disk space2–4 GB for IDE; add 1–2 GB for CODESYS Control Win SL
Display1280 × 768 minimum
.NET Framework.NET 4.7.2 or later
macOS / LinuxIDE runs on Windows only. CODESYS runtime runs on Linux. macOS requires a Windows VM for the IDE.

Download steps

How to download CODESYS

1

Create a free CODESYS Store account

Go to store.codesys.com and register for a free account. The CODESYS Store is where you download the IDE and optionally purchase runtime licenses, add-ons, and device packages.

2

Download CODESYS Setup

On the Store, search for "CODESYS" and select "CODESYS V3.5 SP[latest]". Add it to your cart — it is free. Proceed through checkout (no payment required) and download the setup executable, typically 300–600 MB.

3

Install the IDE

Run the CODESYS Setup executable as Administrator. Accept the defaults. The installer sets up the core IDE, compiler, and standard library. Installation takes 5–15 minutes.

4

Install CODESYS Control Win SL for SoftPLC (optional)

If you want to run programs on your PC without physical hardware, download "CODESYS Control Win SL" from the Store (also free). Install it separately — it runs as a Windows service. In TIA Portal terms, this is equivalent to PLCSIM; in Rockwell terms, this is equivalent to Emulate 5000.

5

Create a project and select target

In CODESYS IDE, create a new Standard Project. Select "CODESYS Control Win V3" as the device target (for SoftPLC) or your specific hardware device (requires its device description package). Add a PLC_PRG program, write your first rung, and click "Online → Login" to download to the SoftPLC runtime.

What you actually write

The IEC 61131-3 concepts you program in CODESYS

Once CODESYS is installed, your first programs are made of the same standard building blocks every IEC 61131-3 IDE shares: ladder rungs, the scan cycle, IEC timers, and structured text. These are exactly the concepts you can rehearse in the browser before — or instead of — the local install.

A CODESYS ladder diagram (LD) rung — normally-open and normally-closed contacts driving a coil, the first program most CODESYS learners writeA 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
A Ladder Diagram (LD) rung — contacts and a coil, identical in CODESYS and in the browser simulator.
The CODESYS SoftPLC scan cycle — read inputs, execute the IEC 61131-3 program, then update outputs, repeating every cycleThe repeating PLC scan cycle: read inputs, execute the ladder logic, update outputs, then housekeeping, looping continuously.1Read Inputs2Execute Logic3Update Outputs4HousekeepingSCANCYCLE
The scan cycle the CODESYS Control Win SL runtime executes: read inputs → solve logic → write outputs.
An IEC 61131-3 TON on-delay timer as used in CODESYS — output Q turns on only after the preset time elapses while the input stays trueA 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
A standard IEC TON timer — the same function block CODESYS compiles from its standard library.
An IEC 61131-3 Structured Text (ST) snippet — the text-based CODESYS language for math, comparisons and control flowA 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 (ST) — CODESYS's text language for arithmetic, comparisons, and control flow.
Modbus communication from a CODESYS SoftPLC to remote I/O and devices — the protocol CODESYS uses to reach field hardwareA Modbus master polling three slave devices over a shared serial or TCP link, reading and writing their holding registers and coils.MASTERpolls slavesModbus RTU / TCPID 01regs/coilsID 02regs/coilsID 03regs/coilsrequest / response polling
CODESYS speaks Modbus (and many other fieldbuses) to reach remote I/O — one of the comms layers you configure after the IDE is installed.

Faster path for learners

When browser-based practice beats installing CODESYS

CODESYS is genuinely free and well-worth installing. But the setup path — account creation, download, install, SoftPLC setup, project configuration — can take 30–60 minutes before you write your first rung. For learners who want to practice IEC 61131-3 ladder logic immediately without Windows, or who are on macOS/Chromebook/Linux, our browser simulator is faster to start:

A browser-based IEC 61131-3 simulator running a ladder rung with no install — start practising CODESYS-style logic instantly while the CODESYS download completesA web browser window running a PLC ladder logic simulator with an input/output strip, requiring no installation or download.plcsimulator.app/playno installINPUTSOUTPUTS
No CODESYS account, no SoftPLC service, no Windows — open a tab and write IEC 61131-3 ladder logic now.

Zero install

Open a browser tab and start writing ladder logic. No download, no IDE, no SoftPLC service, no device configuration. Useful for quick concept checks and learning sessions on any OS.

Scored scenarios

Our scenarios are automatically graded — the simulator runs all test cases against your logic and tells you whether your solution is correct. CODESYS's SoftPLC does not include a scenario grading layer.

Cross-dialect practice

Switch between Allen-Bradley, Siemens, and IEC 61131-3 dialect tracks in the same session — useful when you need to compare how the same circuit is written across platforms.

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Related guides

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Questions

CODESYS download FAQ

The CODESYS Development System IDE is free to download and use without a time limit. You can write, compile, and deploy programs to any CODESYS-compatible runtime without paying for the IDE itself. The SoftPLC runtime (CODESYS Control Win SL) is free in demo mode but stops executing after 2 hours and must be manually restarted. For production or long-session testing, a paid runtime license is required. Summary: IDE = free forever; SoftPLC demo mode = free with 2-hour cut-off.

IEC 61131-3 ladder logic — free in your browser, any OS.

No 2-hour demo limit. No Windows required. Graded scenarios.

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