The Day I Stopped Caring Which PLC Brand We Used

The purchasing manager walked into my office with a quote. $47,000 for Studio 5000 licenses. Five seats. Annual maintenance not included.

"We need these," she said. "The vendor says we can't program the new line without them."

I looked at the quote. Then at the three S7-1500 PLCs collecting dust in our spare parts room. Then at the CODESYS controller we bought last year for the packaging line. Then back at the quote.

"No," I said.

The Hostage Situation

Let me tell you how vendor lock-in actually works in the real world.

Twenty years ago, we bought Rockwell PLCs for Line 1. Made sense — they were solid, the integrator knew them, and everyone in the region used them. We bought Studio 5000 (RSLogix 5000 back then). $8,000 per license. Expensive, but one-time, right?

Wrong.

Ten years later, we needed to expand. Rockwell had changed the licensing model. Now it's subscription. And the old perpetual licenses? Not compatible with the new PLCs. Want to program the new CompactLogix? Buy new licenses. At the new price. Which had doubled.

Oh, and your ladder logic from 2006? Good luck importing it. Version incompatibility. We ended up rewriting 40% of it by hand.

Then came Line 2. Different integrator. They used Siemens. "No problem," they said, "TIA Portal is industry standard."

Now we have two ecosystems. Two software platforms. Two sets of licenses. Two groups of engineers who can't help each other because they don't speak the same programming language.

Line 3? The bean counters saw "CODESYS" and "open standard" and got excited. Cheaper hardware, they said. We bought it. Guess what? Still vendor-specific. Still locked in. Just locked into a different vendor.

We weren't choosing the best PLC for the job. We were choosing which company owned us next.

The Moment Everything Changed

I was at a conference last year. Sitting in the back of a session about IEC 61131-3. Boring stuff — the standard nobody thinks about because "everyone knows Rockwell" or "Siemens is industry standard."

The speaker said something that stuck with me:

"The PLC vendors convinced you that vendor-neutral is impossible. But IEC 61131-3 already solved this problem in 1993."

I went back to my hotel room and did something I should've done 20 years ago: I actually read the IEC standard.

Turns out, ladder logic is ladder logic. A TON timer works the same whether it's running on Rockwell, Siemens, Schneider, or Mitsubishi. The only difference is the file format.

XML. It's all just XML.

L5X for Rockwell. SimaticML for Siemens. XEF for Schneider. PLCopen for everyone else. Different wrappers. Same logic underneath.

I realized: We've been paying tens of thousands of dollars for XML converters.

The Experiment

I downloaded a vendor-neutral IDE called Plaxio. Free. Runs on Mac and Windows. IEC 61131-3 compliant.

I took one of our standard motor control programs. The one we've deployed 50 times across three production lines. Copied it into Plaxio.

Then I did something I'd never been able to do before:

I exported it to L5X. Imported into Studio 5000. Worked.

I exported the same program to SimaticML. Imported into TIA Portal. Worked.

I exported it to PLCopen XML. Imported into CODESYS. Worked.

One codebase. Three vendors. Zero rewrites.

I sat there staring at my screen for 20 minutes. Then I called the purchasing manager.

"Cancel the Studio 5000 order."

What Happened Next

We re-bid the new production line. This time, the RFQ said: "Vendor-neutral PLC acceptable. Must support IEC 61131-3 and PLCopen XML export."

Three bidders submitted Rockwell quotes. Two submitted Siemens. One submitted a CODESYS-based PLC I'd never heard of — at 40% less cost.

Old me would've thrown out the CODESYS bid. "Not a real brand." "No one uses those." "What if we can't find integrators?"

New me looked at the specs. CPU faster than our existing CompactLogix. More I/O. EtherCAT. And here's the kicker: it didn't matter.

Because we weren't writing vendor-specific code anymore. We were writing IEC standard code that ran anywhere.

We took the CODESYS bid. Saved $31,000 on hardware. Saved another $47,000 by not buying Studio 5000 licenses.

The integrator asked what programming software we wanted them to use.

"Doesn't matter," I said. "Give us the PLCopen XML file when you're done. We'll handle the rest."

The Real Cost of Vendor Lock-In

It's not just the licensing fees. It's everything that comes after:

• You can't negotiate. When Rockwell raised prices 30% last year, what were we going to do? Rewrite every program? Rip out every PLC?
• You can't hire. "Must have 5 years Studio 5000 experience" narrows your talent pool to a fraction of controls engineers.
• You can't optimize. That new PLC with built-in motion control and half the cost? Can't use it. Wrong vendor.
• You can't reuse code. Every line is a different vendor. Every program is rewritten from scratch. Again. And again.
• You can't innovate. Want to try edge computing PLCs? AI-optimized controllers? Too bad. Your vendor doesn't make those yet.

What Vendor-Neutral Actually Means

People hear "vendor-neutral" and think it's some academic pipe dream. It's not.

Here's what it means in practice:

1. Write Once, Deploy Anywhere

We developed our packaging line logic in Plaxio. Exported to L5X for the filling station (Rockwell PLC). Exported to SimaticML for the palletizer (Siemens PLC). Same program. Different hardware. Zero rewrites.

2. Version Control That Actually Works

Ever tried using Git with Studio 5000? It's a binary file. You can't diff it. You can't branch. You can't merge.

IEC standard code? Plain text. We have the entire plant in GitHub. Branching. Pull requests. Code review. Like real software.

3. AI That Understands Your Code

Vendor-specific formats? AI can't read them. IEC standard? It's just structured XML. AI can generate it, debug it, document it, optimize it.

Last week I asked AI to "add overload protection to all motor rungs." Three seconds later, done. Across 40 programs. Try doing that in Studio 5000.

4. Instant Documentation

Plaxio generates Word docs, PDFs, HTML from the code. Auto-updating I/O lists. Wiring diagrams. Logic flowcharts. No more "the documentation is outdated" because the code IS the documentation.

The Questions People Always Ask

"What about vendor-specific features?"

Like what? MSG blocks? GSV/SSV? Add-On Instructions?

95% of PLC logic doesn't use those. It's motors, valves, timers, counters. Standard IEC stuff.

For the 5% that needs vendor-specific features, fine. Write that part in the vendor's tool. But don't let 5% hold the other 95% hostage.

"What about support?"

When was the last time Rockwell support actually solved your problem?

You know what solves problems? Engineers who understand IEC 61131-3. Not engineers who only know one vendor's dialect of ladder logic.

"What about my existing code?"

Import it. Plaxio reads L5X, SimaticML, XEF, PLCopen XML. Your existing programs work day one.

The Future I Want

I want to spec a production line based on what it needs. Not based on what vendor owns me.

I want to hire engineers who know automation. Not engineers who know "Rockwell" or "Siemens."

I want code that outlives the hardware. That migrates when technology changes. That doesn't become obsolete when a vendor decides to EOL a product line.

I want to stop paying $10,000/year for software that should be $100.

And you know what? That future already exists. We just have to stop accepting the old way.

What I'm Doing Now

We're migrating everything to vendor-neutral development. Not overnight — we're not ripping out working PLCs. But every new project, every major revision, gets developed in Plaxio first.

When Line 4 goes online next quarter, it'll be the first line we've commissioned in 15 years where I genuinely don't care what PLC the contractor installs.

Because we'll have the code ready. For any vendor. In any format. With full simulation. With auto-generated docs. With version history going back to day one.

Try doing that in Studio 5000.