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.
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.
CODESYS implements all five IEC 61131-3 languages — the same standard languages whichever vendor's hardware you target.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 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 Ladder Diagram (LD) rung — contacts and a coil, identical in CODESYS and in the browser simulator.The scan cycle the CODESYS Control Win SL runtime executes: read inputs → solve logic → write outputs.A standard IEC TON timer — the same function block CODESYS compiles from its standard library.Structured Text (ST) — CODESYS's text language for arithmetic, comparisons, and control flow.
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:
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.
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.
CODESYS is the programming engine embedded in over 400 hardware products from more than 100 vendors: Beckhoff TwinCAT, Wago e!COCKPIT, Phoenix Contact PLCnext Engineer, Schneider Machine Expert (formerly SoMachine), Bosch Rexroth ctrlX, Eaton XSoft, Festo CECC, Mitsubishi MELSOFT iQ Works (Melsec iQ-R series via CODESYS runtime), Raspberry Pi via OpenPLC or CODESYS for Raspberry Pi, and many more. The IDE is identical across vendors; only the hardware-specific device description files differ.
CODESYS Control Win SL (the SoftPLC runtime that runs on Windows) operates in demo mode without a license. In demo mode, the runtime executes normally for 2 hours of continuous operation. After 2 hours the runtime stops and must be restarted. This resets the 2-hour clock. For learning and short test sessions this is typically acceptable. For longer test sessions or production use, a paid runtime license removes the limit.
Download the latest stable release from the CODESYS Store — the current release is CODESYS V3.5 SP19 or later depending on when you are reading this. V3.5 is the current generation; V2.3 is a legacy version still in use for older hardware but no longer actively developed for new projects. If you are learning from scratch, always use the latest V3.5 release.
The CODESYS Development System IDE runs on Windows only. The CODESYS runtime is available for Linux (CODESYS Control for Linux SL) and for Raspberry Pi, but the IDE you use to write programs still requires Windows. macOS users typically run CODESYS in a Windows virtual machine. If you want to practice IEC 61131-3 ladder logic on macOS, Linux, or Chromebook without a VM, our browser-based simulator is the practical alternative.
Yes — TwinCAT 3 is built on top of CODESYS V3. The project structure, IEC 61131-3 languages, POUs (Program Organization Units), variable declaration blocks, and most standard library function blocks are identical. The main Beckhoff-specific additions are the TwinCAT realtime extension, EtherCAT device configuration, and the Beckhoff TcXxx library function blocks. Your CODESYS ladder logic and structured text knowledge transfers directly; only the Beckhoff-specific extensions need additional learning.
The CODESYS Development System setup includes the CODESYS Control Win SL SoftPLC in demo mode, which acts as a software PLC on your Windows machine — this is CODESYS's built-in simulator equivalent. There is also a "Simulation" mode you can toggle inside the IDE (Online → Simulation) that runs your program without any runtime at all, useful for quick logic checks. The demo SoftPLC runs for 2 hours per session; the in-IDE Simulation mode has no such limit but is less representative of real-time behavior. For instant, cross-platform practice you can use a browser-based IEC 61131-3 simulator with no install at all.
Both are free and both use IEC 61131-3, so the ladder, structured text, and function-block skills transfer between them. CODESYS is the industry-reference IDE embedded in commercial hardware from 100+ vendors, with a richer toolset and the 2-hour SoftPLC demo limit. OpenPLC is fully open-source (GPL) and aimed at running real logic cheaply on a Raspberry Pi, Arduino, or ESP32 over Modbus. If you are targeting commercial industrial hardware, learn on CODESYS; if you want a free open-source runtime for hobby or hardware projects, OpenPLC is excellent. Either way, you can rehearse the shared IEC 61131-3 core in the browser first.
IEC 61131-3 ladder logic — free in your browser, any OS.
No 2-hour demo limit. No Windows required. Graded scenarios.
CODESYS download and installation guide: transfer checklist
Direct answer
The reader can verify the official download, select the correct development release and target package and run a bounded offline IEC project before hardware work.
Written for iEC 61131-3 learners and controls developers obtaining the official CODESYS environment and distinguishing the free IDE from licensed runtimes and target packages.
System map / 02
NODE 01observable
01
Platform context
The required development-system release, operating system, IEC languages, controller target and runtime or simulation need.
NODE 02observable
02
Tags and addressing
Official installer, package manager, device description, runtime license, target vendor and project version.
NODE 03observable
03
Reference pattern
One offline IEC program compiled and executed with known inputs and outputs.
NODE 04observable
04
Timing and limits
32-bit or 64-bit packages, target compatibility, libraries, gateway, firewall, runtime expiry and project conversion.
NODE 05observable
05
Diagnostics
An installer, package, library, gateway, license or target mismatch captured from exact diagnostics.
NODE 06observable
06
Official-tool transfer
The project backed up, compiled and accepted in the supported target environment.
