Free PLC Simulator Online: Ladder Logic and a Live Plant

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A free online PLC simulator that shows the plant

Most PLC simulators show you a ladder diagram and a few lights. The EDWartens PLC lab shows you a plant. You write ladder logic, press Simulate and watch the equipment respond, so you can see straight away whether your program does what you meant. It is a free online PLC simulator and it runs in your browser.

The video above shows the idea in sixteen seconds. Here is what is happening.

Step 1: build the ladder in LADX Mini

LADX Mini is the PLC editor in the lab. You place contacts and coils on rungs to build your program, the same way you would in ladder logic on a real PLC. If you are new, a simple start and stop rung for a pump is a good first program.

Step 2: press Simulate

When your rungs are ready you press Simulate. The program starts to scan, and the lab drives the plant from your logic. There is no download, no licence and no hardware to connect.

Step 3: watch the pump respond

This is the useful part. As you change inputs, the pump in the plant starts and stops in step with your rungs. If it does not behave, you look at the ladder, find the rung that is wrong and fix it. Seeing a cause and an effect is how ladder logic stops being abstract.

Ladder, Structured Text and SFC

Ladder is the most common way to learn, but real projects use more than one language. The lab supports ladder, Structured Text and SFC, which are three of the standard PLC languages, so you can try the same job in different styles and see which suits you.

Who it helps

Students without access to a PLC can practise at home. People moving into automation from electrical or mechanical work can learn the logic before they touch a real controller. Working programmers can test an idea quickly. Because it runs in your browser, you can even practise on a phone.

Open the free PLC lab and write your first rung.

A first exercise

Make a pump start when a start button is pressed and keep running until a stop button is pressed. That small program teaches latching, which you will use in nearly every machine. When it works, add a high level switch that stops the pump, and test that too.

See what other learners have finished on the learner wins page.