Best PLC Simulator Software 2026: Free, Online, Vendor Tools

There is no single best PLC simulator for every job. Use the controller manufacturer’s emulator when project-file and firmware fidelity matter. Use a plant simulator such as Factory I/O when the main test is PLC-to-machine interaction. Use a browser learning simulator when access, repeatable exercises, and fast feedback matter more than exact controller emulation.

This guide was rechecked on July 25, 2026 against product documentation and current release pages. The free online simulator comparison was added on October 24, 2026 from each publisher's own site. It does not reproduce reseller prices or assign unsupported review scores. Licence scope, supported controller families, and feature availability change; confirm them with the publisher before purchase or project approval.

If your primary goal is learning rather than firmware-exact emulation, begin with the hands-on PLC training guide and use this comparison to choose the right simulation layer.

Best PLC simulator by use case

The correct choice often combines two products: a vendor emulator for control execution and a plant model for sensors, actuators, loads, and faults.

Simulator, emulator, and digital twin are not synonyms

Learning simulator

A learning simulator reproduces enough PLC behavior to teach scan order, contacts, coils, timers, counters, sequences, and diagnostics. It may use vendor-like syntax without claiming binary compatibility with a vendor runtime.

Controller emulator

A controller emulator targets a named controller family or firmware environment. Its value is the ability to download or execute a vendor project with fewer changes. Even then, read the vendor’s unsupported-feature and hardware-behavior notes.

Plant simulator

A plant simulator models the equipment controlled by the PLC: conveyors, tanks, sensors, valves, robots, drives, and faults. The control runtime may be external.

Digital twin

“Digital twin” is too broad to use as a fidelity claim by itself. Ask what is synchronized, which physical behavior is modeled, how the model is calibrated, and which acceptance tests it can support.

Our comparison method

The seven tools are compared on observable capabilities, not a weighted “editor score.”

1. Runtime target: generic learning engine, SoftPLC, or named vendor family.
2. Project path: whether a real vendor project can be downloaded without translation.
3. Plant model: switches only, 2D/3D scenarios, or an external simulation interface.
4. Fault testing: whether inputs, components, communications, or controller states can be disturbed repeatably.
5. Automation: snapshots, APIs, scripts, test reset, and machine-readable results.
6. Access: browser or installed application, supported operating systems, account, trial, and licence constraints.
7. Evidence: current publisher documentation, release notes, and limitations.

We have not claimed that all seven products were performance-benchmarked on identical hardware. The test protocol later in this guide shows how a buyer can run that evaluation.

1. PLC Simulation Software

PLC Simulation Software is a browser-based PLC learning and practice simulator. The same session can combine an editor, scan-cycle execution, simulated I/O, lessons, and scenario-based exercises. It is best suited to learners and instructors who want a low-setup lab rather than an exact copy of one controller firmware.

The current machine-readable product facts record the free-account policy, curriculum allowance, maintained dialect list, published practice-catalogue label, scenario-access caveat, pricing, and product limitations. Use that versioned record for current quantities and availability rather than relying on a number copied into an article.

Ownership disclosure: plcprogramming.io and PLC Simulation Software are related properties. Product claims above come from the versioned facts endpoint so readers can inspect the source, review date, and limitations.

Best fit

• first PLC course;
• browser or Chromebook labs;
• reusable ladder-logic exercises;
• interview and fundamentals practice;
• comparing syntax patterns across supported dialects.

Limits

It is a learning and prototyping simulator, not a production PLC. Vendor dialect support does not emulate every instruction, task, firmware, communication stack, safety function, or project file. Native vendor project export is not guaranteed. Final testing must use the target controller, I/O, network, drives, instruments, safety system, and firmware.

2. Factory I/O

Factory I/O is a configurable 3D factory simulation for automation training. Its documentation describes built-in scenes, industrial parts, tags, failures, and I/O drivers that connect to external PLCs, SoftPLCs, Modbus, and other technologies.

The official installation documentation states that, when no licence is found, the application starts a 30-day full-feature trial with internet access. The release notes show version 2.5.10 dated October 15, 2025 and a preceding update adding S7-PLCSIM V20 support. Verify the latest release at installation time.

Best fit

• plant-response visualization;
• virtual commissioning exercises;
• mapping real or emulated PLC tags to sensors and actuators;
• instructor-led fault injection;
• testing sequences against a changing physical model.

Limits

Factory I/O is the plant side of the test. Exact PLC execution depends on the connected controller or emulator. Driver availability varies by edition, and some integrations require other licensed software. A visually convincing scene does not prove motor dynamics, instrumentation, collision behavior, safety response, or process physics.

3. Siemens S7-PLCSIM and S7-PLCSIM Advanced

Siemens provides simulation products for SIMATIC engineering. Select the edition by controller family, networking need, API need, and TIA Portal compatibility—not simply by the word “Advanced.”

The Siemens S7-PLCSIM Advanced function manual documents downloading a STEP 7 project to a simulated PLC instance, supported product variants, networking, and simulation behavior. Siemens product documentation and advisories should be checked together; security and compatibility notes can change after a manual is published.

Best fit

• projects targeting supported S7 controller families;
• TIA Portal integration;
• multi-instance and external co-simulation where the chosen edition supports it;
• repeatable controller-state tests.

Limits

Do not assume every module, technology object, bus device, clock behavior, safety function, and peripheral is modeled. Confirm the exact CPU, firmware, TIA Portal, PLCSIM version, licence, and external-network mode. Treat a successful simulation as one test stage, not a site-acceptance result.

If you only need to practise Siemens-style ladder before you have TIA Portal and a PLCSIM licence, our related Siemens PLC simulator runs exercises in a browser. It is not PLCSIM and does not open TIA Portal projects.

4. FactoryTalk Logix Echo

FactoryTalk Logix Echo is Rockwell Automation’s emulator for supported Logix controller applications. Rockwell documents project download without code changes for supported targets, multiple controllers/chassis, snapshots, APIs, and version-specific controller features.

Rockwell’s Product Compatibility and Download Center listed FactoryTalk Logix Echo 4.00.00 as active when this guide was reviewed. Version 4 documentation includes ControlLogix 5590 support and Python SDK support. Match the current Logix Designer version, controller family, firmware, activation, and Echo version before building a test plan.

Best fit

• supported ControlLogix and CompactLogix project tests;
• controller snapshots and repeatable state restoration;
• integration with third-party simulation;
• automated regression tests where the installed SDK supports them.

Limits

Echo does not make all physical devices virtual. Drives, motion, safety partners, I/O, communications, and third-party modules need feature-by-feature verification. A project that downloads is not automatically a complete machine simulation.

To practise Logix-style instructions (XIC, XIO, OTE, TON) before you have Logix Designer and an Echo licence, our related Allen-Bradley PLC simulator runs in a browser. It is a learning tool, not a Logix emulator, and it does not open .ACD files.

5. CODESYS Development System

CODESYS says its Development System is available free of charge and includes IEC 61131-3 editors, debugging, visualization, and a demo version of CODESYS Control Win SL.

Best fit

• vendor-neutral IEC 61131-3 practice;
• ladder, structured text, function block, and SFC exercises;
• function-block and library design;
• local debugging and visualization.

Limits

The engineering tool being free does not make every runtime, fieldbus stack, add-on, or device package free. The included Control Win is described as a demo. Confirm the licence and target device before using a project outside a learning lab.

6. OpenPLC

OpenPLC is an open-source editor/runtime project useful for teaching control-program structure and inspecting an accessible software PLC stack. Begin with the current project documentation and maintained repository; old third-party installers frequently outlive the instructions they describe.

Best fit

• open-source learning;
• small IEC-style projects;
• Raspberry Pi and supported-board experiments;
• understanding the separation between editor, generated program, and runtime.

Limits

OpenPLC is not a Siemens, Rockwell, Mitsubishi, Omron, Schneider, or other vendor emulator. Validate supported instructions, I/O mapping, runtime cycle, communications, operating system, and hardware interfaces for the current release. See the OpenPLC tutorial for a local learning workflow.

7. PLC Fiddle

PLC Fiddle is a browser tool for writing and sharing small IEC-style logic examples. It is useful when an instructor needs a low-friction demonstration or a learner wants to test a compact idea.

Best fit

• short examples;
• quick syntax and logic experiments;
• links that can be shared with a reviewer;
• classrooms where installing engineering software is impractical.

Limits

It should not be used to infer compatibility with a particular controller, project format, I/O rack, network, motion system, or safety runtime. Confirm current browser support and terms on the publisher’s site before standardizing a class around it.

Free online PLC simulators compared

Most people searching for a PLC simulator want one that runs in a browser and costs nothing to start. These tools all run ladder logic without installing vendor software. Facts below come from each publisher's own site on October 24, 2026; usage figures are the publishers' own claims.

How to choose between them:

• First PLC course or a Chromebook class: pick a tool that checks your work, not just runs it. PLC Simulation Software, Rungs and plcIOsim all grade or check exercises in different ways.
• Allen-Bradley-style practice: Rungs, plcIOsim, LogixPro and our Allen-Bradley PLC simulator all use XIC/XIO/OTE-style instructions. None of them opens Studio 5000 projects.
• Watching a machine respond: plcIOsim, PLC Simulation Software and LogixPro include animated machine scenes. PLC Simulator Online and PLC Fiddle focus on the rungs themselves.
• Just testing a rung: PLC Simulator Online and PLC Fiddle are the lowest-friction options.

See the free PLC simulators directory for more options, and the LogixPro guide if you are replacing an older classroom licence.

Detailed selection matrix

A reproducible simulator benchmark

Use the same requirement, state model, and expected results for every candidate. Do not compare one product’s beginner demo with another product’s fully configured engineering stack.

Test machine

Implement a two-conveyor transfer:

• Conveyor A feeds Conveyor B.
• B must be proven running before A can start.
• A photoeye counts parts.
• A jam fault occurs if the photoeye remains blocked beyond a configurable time.
• An overload immediately removes the affected run command.
• Reset is ignored while the initiating fault remains active.
• Automatic restart after power restoration is prohibited.

Test cases

For each tool record:

• product, edition, and version;
• host operating system and relevant hardware;
• controller target and firmware model;
• project conversion or code changes required;
• setup steps;
• unsupported instructions or devices;
• test result and evidence filename;
• reset time and manual intervention;
• licence used.

Publish the raw CSV and project files if licences and ownership permit. Without those records, “best” is only an opinion.

How to choose

Choose by the failure you cannot afford to miss

If a wrong instruction behavior is the largest risk, prioritize the vendor emulator. If sequence-to-machine interaction is the largest risk, prioritize a plant simulator. If inconsistent learner access is the largest risk, prioritize a browser environment. If test repeatability is the largest risk, prioritize snapshots, APIs, and deterministic reset.

Check the exact support boundary

Before approval, verify:

• controller catalog and firmware;
• engineering-software version;
• task types and scheduling;
• instruction and Add-On Instruction support;
• produced/consumed tags and messaging;
• safety and motion behavior;
• I/O, drives, robots, and third-party modules;
• network access and virtual adapters;
• API licence and documentation;
• offline, floating, classroom, or concurrent-use terms.

Separate test evidence from visual appeal

A polished 3D animation can still hide a wrong scan order. A controller emulator can execute logic accurately while representing the plant with crude toggles. Evaluate both layers independently.

A safe setup sequence

1. Write the requirement and expected fail-safe state.
2. Define the I/O list and tag ownership.
3. Draw the state model before programming.
4. Build the smallest executable path.
5. Run the normal case once.
6. Run negative and restart tests repeatedly.
7. Capture versioned evidence.
8. Review unsupported behavior.
9. Repeat critical tests on target hardware.
10. Perform formal commissioning and safety validation under the project’s procedures.

Never connect a learning laptop or test simulator directly to a production OT network without authorization, network design review, backups, and an approved test plan.

Simulator limitations that matter

• Scan fidelity: task scheduling, asynchronous I/O, communications, and hardware interrupts may differ.
• Electrical behavior: open circuits, shorts, leakage, grounding, noise, and module diagnostics need physical or hardware-in-the-loop tests.
• Motion and process physics: acceleration, friction, backlash, fluid behavior, and thermal effects require validated models.
• Networks: packet loss, multicast behavior, switch configuration, time synchronization, and security controls need an appropriate lab.
• Safety: standard simulation cannot certify a safety function. Follow applicable lifecycle, verification, and validation requirements.
• Human behavior: operator timing, maintenance actions, and ambiguous alarms need scenario-based review.

Frequently asked questions

What is machine simulation for PLC training?

Machine simulation means your PLC logic runs against a modeled machine instead of real equipment. That machine might be a conveyor, sorter, tank, traffic light or pick-and-place cell. Its sensors change as parts move, and its actuators respond to your outputs, so you can test sequences, interlocks and faults with no risk to hardware. There are two common setups:

• All-in-one learning simulators combine the logic editor and the machine. PLC Simulation Software is our product (PLC Programming and PLC Simulation Software are run by the same team). Its product facts list 170 source-catalogued practice scenarios, and a scenario passes only when the simulated machine shows the required behavior.
• 3D plant simulators such as Factory I/O model the machine and connect to a separate PLC, emulator or soft PLC.

Use the first type for learning. Use the second when you want to test real or emulated controller code against a virtual plant.

What are the best simulation tools for beginners learning industrial automation?

A practical beginner stack has three layers, used in this order:

1. A browser learning simulator with guided lessons and checked scenarios. This lets you practise contacts, coils, timers, counters and sequences without installing anything.
2. The free or trial simulator for the platform your target employers use. Examples are CCW's Micro800 simulator demo, Do-more Designer, TIA Portal's trial with STEP 7 simulation, and the CODESYS demo runtime.
3. A 3D plant such as Factory I/O, once you can write working logic.

Skip expensive licences until a specific job or course needs them.

What is the best free PLC simulator?

For IEC programming on a local computer, CODESYS is a strong starting point, but its included Control Win is a demo. For browser learning, PLC Simulation Software has a documented free tier. For a named PLC family, verify whether the vendor provides a trial or simulator compatible with your exact engineering package.

Is there a free online PLC simulator?

Yes. PLC Simulator Online, PLC Fiddle and the free tiers of PLC Simulation Software, Rungs and plcIOsim all run ladder logic in a browser with nothing to install. They differ in whether they check your work, show a machine responding, or support Structured Text; see the comparison table above.

Is LogixPro still available?

Yes, under a new name. The Learning Pit is renaming LogixPro to Professor Bill's LadderLab, and existing LogixPro licences keep working. It runs on Windows only and is sold per PC.

Is Factory I/O a PLC simulator?

Factory I/O primarily simulates the plant and exposes tags through drivers. It can work with an external PLC, emulator, SoftPLC, or supported control interface. The connected runtime determines PLC execution fidelity.

Can a simulator validate a production PLC program?

It can validate defined parts of the logic and sequence. It cannot alone validate wiring, electrical protection, field instruments, every module, network loading, process physics, safety functions, and site operation.

Should I learn with a generic simulator or a vendor emulator?

Use a generic simulator to learn transferable logic with low setup. Move to the target vendor emulator when project structure, instructions, tasks, communications, and deployment workflow matter.

Source and correction policy

Product-specific claims were checked against PLC Simulation Software’s versioned facts endpoint, Factory I/O documentation and release notes, Siemens S7-PLCSIM documentation, Rockwell Automation’s Logix Echo product and compatibility pages, and CODESYS product documentation. Because editions and licences change, the current publisher page controls. Report a version mismatch through the site’s correction process.