The answer depends on the job
A free browser sandbox is the fastest way to learn ladder logic. An IEC engineering simulator is better for reusable code and libraries. A vendor simulator is the closest match to a specific project—but its IDE, version and licence may not be free. A 3D process simulator adds virtual machinery but may still need a separate PLC runtime.
This page does not publish a winner. The public benchmark protocol has no completed product results yet. Options below are grouped by access and workflow; evidence describes availability, not performance.
At-a-glance access comparison
| Simulator | Type | Free boundary | Platform | Best fit |
|---|---|---|---|---|
| PLC Simulation SoftwarePLC Simulation Software | Browser learning | No-expiry free | Modern browser | Guided ladder/ST practice, multiple teaching dialects and scored scenarios without installing an IDE. |
| ACC PLC SimulatorACC Automation | Browser learning | No-expiry free | Modern browser | Free ladder practice with digital/analog I/O and browser-based 3D scenes. |
| PLC Simulator OnlinePLC Simulator Online | Browser learning | No-expiry free | Modern browser | Opening a visual ladder sandbox quickly on desktop or mobile. |
| OpenPLC Editor + RuntimeOpenPLC Project | IEC engineering | No-expiry free | Windows, Linux and macOS options | Open-source IEC 61131-3 learning, simulated I/O and later deployment to supported hobby/edge hardware. |
| CODESYS Development System + simulation/demo runtimeCODESYS Group | IEC engineering | Free with session limits | Windows engineering workstation | IEC 61131-3 projects, libraries, visualization and manufacturer-independent engineering practice. |
| Connected Components Workbench StandardRockwell Automation | Vendor engineering | Free with session limits | Windows | Micro800 ladder, function-block and structured-text practice in the actual CCW engineering environment. |
| Siemens S7-PLCSIM / PLCSIM Advanced trial pathSiemens | Vendor engineering | Time-limited trial | Windows with compatible TIA Portal release | Testing Siemens S7 projects with the matching TIA Portal and simulator generation. |
| MELSOFT GX Works3 trial + GX Simulator3Mitsubishi Electric | Vendor engineering | Time-limited trial | Windows | MELSEC iQ-F/iQ-R project practice and the simulation function within the vendor engineering workflow. |
| Factory I/O trialReal Games | 3D process | Time-limited trial | Windows | Connecting a PLC/SoftPLC to virtual conveyors, tanks and other 3D plant scenes. |
Detailed options and limitations
Browser learning
PLC Simulation Software
PLC Simulation Software · Modern browser
- Best for
- Guided ladder/ST practice, multiple teaching dialects and scored scenarios without installing an IDE.
- What “free” means
- Free account does not expire; no credit card is required. Access varies by lesson, scenario, account state and rollout.
- Important limit
- Learning/prototyping simulator—not a complete emulation of vendor firmware, every instruction or native project format.
- Evidence note
- Machine-readable product facts reviewed 24 July 2026.
Browser learning
ACC PLC Simulator
ACC Automation · Modern browser
- Best for
- Free ladder practice with digital/analog I/O and browser-based 3D scenes.
- What “free” means
- The current simulator page labels the tool free, browser-based, no-install and no-cost.
- Important limit
- Teaching syntax and scan behavior are not a substitute for the exact target PLC runtime.
- Evidence note
- Publisher page reviewed 26 July 2026.
Browser learning
PLC Simulator Online
PLC Simulator Online · Modern browser
- Best for
- Opening a visual ladder sandbox quickly on desktop or mobile.
- What “free” means
- Publisher describes the visual ladder simulator as free and browser based.
- Important limit
- Confirm supported instructions, save/export behavior and data types against the exercise you need.
- Evidence note
- Publisher documentation reviewed 26 July 2026.
IEC engineering
OpenPLC Editor + Runtime
OpenPLC Project · Windows, Linux and macOS options
- Best for
- Open-source IEC 61131-3 learning, simulated I/O and later deployment to supported hobby/edge hardware.
- What “free” means
- OpenPLC Editor source is GPL-licensed; runtime/editor installation paths depend on platform.
- Important limit
- Not a drop-in emulator for Siemens, Rockwell or another proprietary controller. Verify maintained builds and supported hardware.
- Evidence note
- Official project repository and licence reviewed 26 July 2026.
IEC engineering
CODESYS Development System + simulation/demo runtime
CODESYS Group · Windows engineering workstation
- Best for
- IEC 61131-3 projects, libraries, visualization and manufacturer-independent engineering practice.
- What “free” means
- Development System is free. Its setup includes a demo Control Win SL SoftPLC; CODESYS states unlicensed demo runtimes shut down automatically after two hours.
- Important limit
- A production runtime, target/device package or professional add-on may need a separate licence. Vendor-certified service packs can differ.
- Evidence note
- CODESYS product and store pages reviewed 26 July 2026.
Vendor engineering
Connected Components Workbench Standard
Rockwell Automation · Windows
- Best for
- Micro800 ladder, function-block and structured-text practice in the actual CCW engineering environment.
- What “free” means
- CCW Standard is a free download. Rockwell’s current Micro800 selection guide lists a demo simulator limited to 10 minutes in Run mode; the paid Developer edition has the full simulator.
- Important limit
- Targets Micro800—not MicroLogix, CompactLogix or ControlLogix. Standard and Developer capabilities differ.
- Evidence note
- Rockwell publication 2080-SG001J-EN-P (September 2025) and product page reviewed.
Vendor engineering
Siemens S7-PLCSIM / PLCSIM Advanced trial path
Siemens · Windows with compatible TIA Portal release
- Best for
- Testing Siemens S7 projects with the matching TIA Portal and simulator generation.
- What “free” means
- Siemens documentation provides trial-license behavior for PLCSIM Advanced; availability and bundling must be checked for the exact TIA release/region.
- Important limit
- Standard PLCSIM and PLCSIM Advanced have different communication, API and controller support. Match versions before installation.
- Evidence note
- Current Siemens PLCSIM Advanced manuals reviewed 26 July 2026.
Vendor engineering
MELSOFT GX Works3 trial + GX Simulator3
Mitsubishi Electric · Windows
- Best for
- MELSEC iQ-F/iQ-R project practice and the simulation function within the vendor engineering workflow.
- What “free” means
- Mitsubishi publishes regional/language trial packages. Terms, duration and availability vary by official regional portal.
- Important limit
- Verify supported CPU models, language, installer region and simulator behavior. It is not an FX2N/GX Works2 simulator.
- Evidence note
- Mitsubishi product page, current operating manual and official trial listing reviewed.
3D process
Factory I/O trial
Real Games · Windows
- Best for
- Connecting a PLC/SoftPLC to virtual conveyors, tanks and other 3D plant scenes.
- What “free” means
- Official site offers a full-featured 30-day Ultimate Edition trial.
- Important limit
- It is commercial software after the trial. Editions include different I/O drivers; choose the required PLC/Modbus/OPC connection.
- Evidence note
- Factory I/O trial and edition pages reviewed 26 July 2026.
Choose with a five-case proof, not a feature list
01
Run
Build and run a stop-priority seal-in circuit.
02
Time
Check timer behavior exactly at the preset boundary.
03
Scan
Prove a one-scan edge and execution ordering.
04
Persist
Save, close, reopen and repeat the same result.
05
Transfer
Export/share and document target-hardware differences.
PLC simulator vs process simulator
A PLC simulator executes a controller program and exposes virtual inputs, outputs, tags, timers and scan behavior. A process simulator models the machine or physical process—conveyors, tanks, sensors, motion or faults. Virtual commissioning connects both through a driver or protocol.
Do not assume “connected” means high fidelity. Verify signal mapping, update rates, analog units, fault injection, startup ordering, communication loss and reset behavior.
What simulation cannot sign off
- • Exact module wiring, polarity, commons, isolation or electrical faults
- • Certified safety-function validation
- • Real controller/network timing under installed load
- • Actuator direction, feedback and mechanical movement
- • Process hazards, utilities, interlocks and human response at site
- • Firmware-specific behavior outside the tested version
Frequently asked questions
What is the best free PLC simulator?+
For zero-install beginner practice, choose a browser simulator. For IEC engineering, use OpenPLC or the free CODESYS Development System with its documented demo boundary. For vendor project fidelity, use the exact vendor tool and trial/demo tier. There is no defensible single winner before the same benchmark cases are run on frozen versions.
Is CODESYS completely free?+
The CODESYS Development System is free. The included Control Win SL runtime is a demo, and CODESYS says unlicensed SoftPLC demos shut down automatically after two hours. Production runtimes, target packages and professional add-ons can require licences.
Is the CCW Micro800 simulator free?+
Connected Components Workbench Standard is free, but Rockwell’s current selection guide describes its Micro800 simulator as a demo limited to 10 minutes in Run mode. Developer edition contains the full simulator.
Can simulation replace hardware commissioning?+
No. Simulation can test logic and some interfaces, but it cannot prove real I/O electrical behavior, safety functions, network timing, module diagnostics, actuator movement or process hazards on the target installation.
What is the difference between a PLC simulator and a process simulator?+
A PLC simulator executes control logic. A process simulator models the controlled machine or process. Virtual commissioning often connects both, but the fidelity and protocol interface need explicit tests.