tia-portal-mcp
MCP bridge that connects LLMs and AI agents directly to Siemens SIMATIC TIA Portal for PLC reads and writes.
What it does and how it connects
TIA Portal MCP is an MCP server for Siemens SIMATIC TIA Portal V21 that lets MCP clients and AI agents inspect a running TIA Portal project through the Siemens Openness API. Coverage includes project discovery and lifecycle operations, PLC block export and import, tag table reads, guarded PLC software writes, hardware and network discovery, WinCC Unified HMI inspection and guarded tag-table, tag and alarm writes, standalone VCI workspace operations, library inspection and guarded library writes, cross-reference diagnostics, hardware catalog search, guarded network-device provisioning, and compile and check diagnostics.
The server exposes 9 tools in read-only mode and 21 in read-write mode, which is the startup default; full mode adds no tools or operations, it only runs lifecycle calls without the prompt. Every write tool uses one guarded single-call pipeline, and there are no safety tokens and no PLC run or stop. Reads act on the bound project only and never open or switch a project; without a verified binding they fail closed.
The README documents write safety in detail: plc_write runs up to 50 operations in one call with a dry run preview, execution stops at the first failure without batch rollback, and typed Siemens failures carry an engineering error. The project also ships a doctor command and a troubleshooting guide, and recent issues show active users measuring real costs, such as the token cost of resending a whole PLC block for a one-line change.
What engineers report
The refusal itself is correct and fails closed. The diagnosis is the problem: if nobody declined, the message sends you looking for a person who said no.
2026-11-06Read the originalFor a block of this size almost nobody will do that, so the agent reports "one line changed" and is wrong.
2026-11-06Read the originalThat is about 72,000 output tokens and 9 minutes for one line. TIA Portal is not the bottleneck. The model retyping the document is.
2026-11-06Read the original
Alternatives
Compare side by side- ROSClaw
A physical AI runtime for ROS 2 robots, rather than a bridge into Siemens TIA Portal for PLC work.
- trace (mteichtahl)
An agent loop that runs an electronics repository, triaging failing builds and merging when checks pass, rather than a bridge into TIA Portal.
Recurring errors it addresses
Error Index entries this tool is built to reduce or work around.
- TIA Portal can silently ignore a colliding tag rename, and if a later step in a batch fails the final state is left unverified with no rollback.Error Index
- An MCP server for Siemens TIA Portal could not find PLC or HMI software by its plain name because the fallback matched the container name (CMU_CPU) instead of the software name (CMUR), so every agent call by bare name returned "software container not found".Error Index
Sources
Not verified
- Pricing: none stated on the repo.
- A standalone website: no homepage is listed in the live API record.
- A named individual builder beyond the repository owner handle Czarnak; the LICENSE file names Lukasz Czarnacki as copyright holder.
Last verified November 6, 2026. Listings are informational. The evidence score measures public, verifiable evidence and is not an endorsement or a compatibility claim.