A Factory I/O alternative that runs in your browser
Factory I/O is a respected 3D factory simulator. You connect it to a real PLC or a PLC simulator, and your program runs its conveyors and sorters. PLC Gym also has 3D machines, but the PLC, the code editor and the lessons are built in, in a web browser. Here is how they compare, with the limits of both.
Which should you choose?
Choose Factory I/O if
- You already have TIA Portal, Studio 5000 or a real PLC, and want to test that exact program on a 3D scene.
- You want to build your own scenes from a library of parts.
- You teach on Windows lab PCs with the makers' software installed.
Choose PLC Gym if
- You don't have the makers' software, or a Windows PC.
- You want lessons, tasks and automatic marking in the same place as the machines.
- You want to start in the next minute, with nothing to install or license.
What each can and can’t do
| Question | Factory I/O | PLC Gym |
|---|---|---|
| Where does it run? | PartlyOn a Windows PC. Its trial page asks for Windows 7 SP1 or later and a supported graphics card. | YesAny modern browser on a laptop, desktop, Mac or Chromebook. A phone is fine for trying the machines and reading lessons. |
| 3D machines | YesMore than 20 industrial scenes, and you can build your own from a library of parts. | Partly26 working machines, up to a whole factory. You can't build your own scenes. |
| Where do you write the PLC code? | PartlyIn a real PLC or the maker's simulator (S7-PLCSIM, PLCSIM Advanced or SoftLogix), programmed in the maker's own software. The Starter edition has a built-in soft PLC. | YesBuilt in. Siemens SCL, LAD, FBD and GRAPH; Rockwell Structured Text, Ladder, FBD and SFC; Beckhoff TwinCAT Structured Text. |
| Does it work with real PLCs? | YesYes. Siemens and Allen-Bradley PLCs over Ethernet, plus OPC UA and Modbus TCP. | NoNo. PLC Gym runs its own simulator of each maker's languages, not their software. You can bring in your own Siemens SCL, Studio 5000 Structured Text or ladder, or TwinCAT code to try on a 3D machine, and export SCL as an .scl file or Rockwell code as an .L5X file. |
| Lessons and marking | PartlyThe pages we checked list no built-in course or automatic marking. It has an instructor mode for exercises and fault-finding challenges. | YesA step-by-step course, 74 missions and 20 challenges. Automatic tests check every one, scan by scan. |
| Price | PartlyStarter from €40 a year, Ultimate from €278 a year. The Siemens and Allen-Bradley editions are from €158 a year, or €435 once. A 30-day free trial of Ultimate. | YesA free plan for good. Pro is £15 a month or £144 a year. Everything is free while we test, until 5 December 2026. |
PLC Gym’s own limits are in the table too. The language reference lists where its simulator differs from TIA Portal and Studio 5000.
Try the same task here
Common questions
Is PLC Gym a free Factory I/O alternative?
It has a free plan for good: the basics, two guided labs, the first course module and 9 challenges. Pro is £15 a month. Everything is free while we test, until 5 December 2026.
Can I connect PLC Gym to a real PLC or to PLCSIM?
No. PLC Gym runs your code on its own simulator in the browser. If you need to test a real PLC or a PLCSIM project against a 3D scene, Factory I/O is the right tool.
Do I need TIA Portal or Studio 5000 for PLC Gym?
No. The editors are built in. When your code works, you can export Siemens SCL as an .scl file for TIA Portal and Rockwell code as an .L5X file for Studio 5000. You can also bring code written there into PLC Gym to try on a machine.
Where these facts come from
Checked on 31 October 2026. Prices and features change, so check Factory I/O’s own site before you buy.
Factory I/O is a trademark of its owner. PLC Gym is independent and is not affiliated with or endorsed by its makers.