What is a PLC?

We’re answering your question, “What is a PLC?”

It’s a little computer and the letters stand for “programmable logic controller.”

But what does it do, and why should you care?

Watch here:

“It’s a trap!” – Admiral Ackbar

Dodging TIE fighters, we make our way to the Death Star.

This planet-destroying super weapon could run a little smoother with the help of PLCs.

The PLC itself usually isn’t much to look at it — often just a little box.

But it’s a vital part of many things you see and use every day.

Here’s how PLCs can work, with help from Context Industrial Security Chief Engineer Mike Toecker.


PLC or programmable logic controller
A PLC or programmable logic controller. Image: Surasak Petchang/iStock

“Into the garbage chute, fly boy!” – Leia

You may remember the crew from Star Wars: A New Hope jumping into a garbage chute to escape sharpshooting Stop Troopers.

Leia, Luke, Han Solo and Chewbacca land in a watery, odorous pit, leading to Han Solo’s announcement, “I got a bad feeling about this.”

The trash compactor they find themselves in likely makes use of PLCs, Toecker said.

For example, a sensor in the compactor could monitor the amount of trash.

It may tell the PLC, “Garbage levels are high.”

The PLC says, “High garbage levels? Then I’ll tell the compactor to start crushing.”

And so, the masher goes to work.


A PLC could help run the Death Star's garbage compactor
Leia, Han Solo & Luke Skywalker struggle remain alive in the Death Star’s garbage compactor. Image: Star Wars: A New Hope/Lucasfilm

“Power! Unlimited power!” — Darth Sidious

You can program PLCs to do all kinds of things.

A platform senses the weight of stormtroopers?

Activate the riser, bringing them to the floor of Bay 327.

The elevator senses that it has reached Detention Block AA-23?

Open the door and let the two heroes disguised as troopers to guide their “prisoner,” Chewbacca, into the control center.

Just used the Death Star to blow up a planet and drained your charge?

The PLC can automatically start the re-charging, so you can destroy more rebels.

The next time you see something happening automatically in an industrial setting, it could be a PLC in action.

Or it could be the force.

Elevators can use PLCs to operate. Image: Wolfgang Borchers

“Always in motion is the future” – Yoda

You’ll find PLCs all over in the real world, from car makers to power plants to airports.

Unfortunately, like the one on the Death Star, PLCs can be hackable.

In New Hope, R2D2 plugs himself in to the space station and stops all of the garbage mashers on the station, just before Leia and the crew are crushed to death in a pile of flattened metal.

Companies using PLCs in real life have to protect them or attackers can mess with sensitive and potentially destructive equipment, as well as critical things that people rely on to live.

In the infamous Stuxnet attack in 2010, attackers hacked their way into the PLCs that controlled centrifuges for the Iranian nuclear program, causing the centrifuges to spin out of control and destroy themselves.

Researchers have reported a number of PLC vulnerabilities, like this one that can stop the controller from communicating and security flaws that let attackers hack PLCs that control building heating, ventilation, and air conditioning systems.

This one allows attackers to remotely stop and start the PLC at will.


R2D2 hacks the Death Star & possibly a PLC
R2D2 hacks the Death Star to try to stop the garbage mashers. Image: Star Wars: A New Hope/Lucasfilm

“Somebody has to save our skins” – Leia 

Car makers started using PLCs back in the 60’s.

They were designed to be used in an isolated, controlled environment, not connected to a network.

And especially not the Internet.

Now, more and more companies are connecting things and potentially putting their PLCs at risk.

It may be time to pay more attention to these little computers that help run so many systems in our world — and likely other worlds across the galaxy.



“Yub nub!” – Ewok celebration 

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Main image: Space station. Image: AlexMirnyy1983

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