2026-TwinCAT-Codex

Build TwinCAT 3 projects through Visual Studio 2022, parse TwinCAT and PLC compiler output, generate structured error reports, and drive iterative source fixes until the build is clean or a human decision is required. Use when Codex needs to modify TwinCAT source files, run VS2022-based builds, inspect build errors or warnings, and repeat the edit-build-check loop on .sln, .tsproj, .plcproj, .TcPOU, .TcGVL, and .TcDUT projects.

Read and explain TwinCAT 3 PLC projects with emphasis on Structured Text logic, project structure, task execution context, variable scope, NC axis references, I/O bindings, and EtherCAT relationships. Use when Codex needs to inspect TwinCAT solution files, .tsproj files, .plcproj files, .TcPOU/.TcGVL/.TcDUT source, device mappings, NC links, or EtherCAT topology and produce an accurate explanation instead of treating the code like generic application software.

Enforce TE1030-compliant documentation comments whenever TwinCAT 3 source files are created or modified. Use when Codex edits .TcPOU, .TcGVL, .TcDUT, methods, interfaces, or declarations and must ensure the final code includes TE1030-ready summary, description, and param comments instead of leaving documentation as an afterthought.

Trace TwinCAT 3 symbol mappings across PLC code, task links, NC axes, axis groups, process-image channels, and EtherCAT or XTS-related objects. Use when Codex needs to answer where a PLC variable is mapped, how an AXIS_REF or AXES_GROUP_REF connects to NC objects, which terminal or device path a symbol belongs to, or how to read mapping sections in .tsproj files.

Write and rewrite TwinCAT 3 source-code comments so they comply with TE1030 TwinCAT 3 Documentation Generation markup rules. Use when Codex edits .TcPOU, .TcGVL, .TcDUT, or related TwinCAT source and the resulting comments must be valid for TE1030 documentation output, including summary, description, example, param, note, image, cross-reference, and audience markups.