The decision you live with for ten years
A PLC choice on a new line is not a one-year decision. The customer's maintenance team will live with the IDE, the comms libraries, and the spare-parts supply chain for the lifetime of the cell. Picking by feature checklist alone misses the point — the right question is "who will own this in 2034".Three platforms we use across most of our work, and where each one earns its place.
Siemens TIA Portal (S7-1200 / S7-1500)
Where it wins: anywhere with a Siemens-trained maintenance team — which, in central and eastern Europe and most of the Turkish manufacturing base, is most factories. The integration story with Sinamics drives, Profinet IO, and Simatic HMIs is genuinely seamless.Where it hurts: license cost. TIA Portal isn't cheap, and the version-bundling story (V17 vs V18 vs V19) is a constant maintenance overhead. The IDE is heavy and slow on anything below a recent ThinkPad-class laptop.
Use when: customer has Siemens muscle memory; line is integrated with existing Profinet infrastructure; long-term maintenance is the priority over development speed.
Beckhoff TwinCAT 3
Where it wins: PC-based control. TwinCAT runs on a Windows / RT-Linux box, gives you EtherCAT mastership in software, and lets you write motion logic in C++ alongside ladder/SCL. For high-axis-count motion, vision-integrated cells, and anything where the PLC also runs analytics, it's the cleanest answer.Where it hurts: PC reliability. A panel PC running TwinCAT is more capable than an S7-1500, but it's also a Windows machine in a factory, with everything that implies.
Use when: motion-heavy cell; tight integration with vision or PC-side analytics; team is comfortable in C++ and structured text.
Codesys-based platforms (WAGO, Phoenix Contact, B&R, others)
Where it wins: cost-sensitive deployments, vendor flexibility, and the IEC 61131-3 ecosystem. The same Codesys IDE drives controllers from many vendors, so spare-part / vendor-switch flexibility is real.Where it hurts: vendor-specific extensions break the "write once" promise more often than the marketing suggests. The library coverage for advanced motion or specific drive integrations lags Siemens / Beckhoff.
Use when: cost is the binding constraint; the team isn't locked into a single vendor; the application is mostly logic, not exotic motion.
The selection checklist we run
- Who is the maintenance team in 5 years? Their training defines the answer more than features do.
- How many axes of motion, and how synchronised? Above ~6 tightly-synced axes, Beckhoff or a Sinamics-S7 setup wins.
- Is there a PC-side application sharing data with the PLC? If yes, OPC UA on Beckhoff or Siemens; PC-IPC integration on Beckhoff is tightest.
- Spare parts logistics: can the customer get a replacement controller in 24 h locally? Siemens almost always wins this in TR / EU.
- Cybersecurity posture: does the customer require IEC 62443? Each vendor's compliance story differs.
One pattern we'd avoid
Mixing platforms within a single cell unless there's a strong reason. We've inherited cells with a Siemens main PLC, a Beckhoff EtherCAT slave for motion, and a Codesys-based safety controller. Every retrofit on that cell takes three IDEs and a long afternoon. The single-platform cell is the maintainable cell.What's your default? Curious whether anyone is shipping new lines on Allen-Bradley in this region in 2026.
