Siemens vs Rockwell: when to choose each in a European project

This comparison won't tell you one brand is better than the other, because it's not. Both solve the same problem with different philosophies, and picking wrong isn't picking the "worse" brand — it's picking the one that doesn't fit your plant, your reference supplier or your maintenance team.

Software: TIA Portal vs Studio 5000

TIA Portal integrates PLC programming, HMI design (WinCC), network configuration and, in advanced ranges, motion control into a single environment. That integration is its biggest advantage: fewer jumps between tools, a single project containing everything.

Studio 5000 (Logix Designer) separates the pieces more — FactoryTalk View for HMI, FactoryTalk AssetCentre for version management — but each piece is solid on its own, and Rockwell's "tags" model is, for many programmers with computer-science background, more intuitive than Siemens's data-block addressing.

Neither is "easier". Both have a real learning curve of several months to master properly, not just to program a simple ladder.

Hardware and ranges

In the entry range, the S7-1200 and the CompactLogix (or Micro850) compete in a similar price and features range. In the mid-high range, the S7-1500 and the ControlLogix are functionally equivalent: both support motion, integrated safety (F-CPU one, GuardLogix the other) and deterministic communications. If you're starting from scratch and still wondering what exactly a PLC is and how it works, start with What is a PLC? before jumping into the comparison.

The real hardware difference isn't in features — it's in the distributor network and delivery times in your country. Siemens has a more consolidated industrial presence across Europe due to its historical weight in automotive; Rockwell is strong in plants with American parent companies or in sectors like food where FactoryTalk has traction.

Profinet vs EtherNet/IP

This point usually decides itself just by looking at what's already installed in the plant, not through a technical comparison in the void:

• Profinet dominates in Europe due to Siemens's historical weight in the continent. Determinism via IRT (Isochronous Real Time), good integration with decentralised periphery (ET200SP).
• EtherNet/IP dominates in North America. Uses CIP (Common Industrial Protocol) as application layer, which makes integrating third-party ODVA-certified devices easier.

If your plant already has Profinet infrastructure installed — cabinets, managed switches, periphery — bringing EtherNet/IP into a new project adds network complexity without a clear benefit, and vice versa.

Licensing and total cost over 5-10 years

Here's the most expensive mistake we see repeated: comparing only the PLC list price. A platform's real cost is composed of:

1. Programming software: TIA Portal or Studio 5000 license, per seat and version.
2. Internal team training: if your maintainer already masters a platform, changing brand has a real training cost, not just hardware.
3. Spares and availability: a discontinued module in local stock is worth more than a "cheaper" one that takes 6 weeks to arrive.
4. Technical support: how many integrators in your area master this brand? Fewer suppliers means higher rates when you have a critical incident.

Technician availability in Europe

In continental Europe, Siemens's historical presence in automotive has trained more technicians in TIA Portal than in Studio 5000. Rockwell has stronger talent pools in areas with more American-parent industry. This data — more than any features comparison — is often the criterion that should weigh most in your decision: a plant with the best technology in the world and nobody nearby to maintain it is a plant stopped more days per year.

Migrations: when it makes sense and when it doesn't

Migrating from a PLC-5 or SLC-500 (Rockwell, end-of-life for years) or from an S7-300 (Siemens, end-of-life) is not just "changing the brain". It involves reviewing I/O, communication network, HMI and, if there's safety, recertifying. We don't recommend it as a low-budget isolated project: if you're going to touch the PLC, it's the time to audit the whole cell.

What we always avoid is "and while we're at it, let's also change brand" without a clear business reason. Changing ecosystems without necessity multiplies the project's risk without proportional value.

Our real decision criteria

When a customer asks us "Siemens or Rockwell?", the questions we ask before answering are:

1. What does the rest of the plant already use?
2. Who will maintain this when we're not standing in front of it?
3. Is there a corporate parent with a group standard?
4. Is there integration with robots or SCADA that already condition the protocol?

80% of the time, the answer was already in the plant itself before opening the catalogue. Mastering both brands — which is exactly what we do at DAXP — is not an empty sales argument: it's what lets us answer that question without catalogue bias, because we don't depend on selling the brand that pays us the best commission.

And when the project requires certified safety — normal in automotive, food with robots or any cell with operator access — the PLC brand is only part of the equation. The other part is programming that safety architecture (ProfiSafe, F-CPU) on top of the spec already defined for the project.

Frequently asked questions

Is Siemens or Rockwell more expensive?

Hardware is comparable in the middle range. The bigger difference is in software and licensing. Over 5 years, total cost usually tips based on local technician availability, not on PLC list price.

Profinet or EtherNet/IP — which is better?

Neither is objectively better: depends on which protocol is already installed in your plant. In Europe, with European suppliers, there's usually already Profinet infrastructure.

Can I mix Siemens and Rockwell in the same plant?

Yes, it's common in automotive with lines of different generations. It integrates via OPC-UA or protocol gateways, with an integrator who truly masters both environments.

Is migrating an old PLC-5 or SLC-500 worth it?

If the equipment is still in production and spares are scarce, yes. The cost of a line stoppage from a discontinued module usually exceeds several times the cost of a planned migration.