Function Blocks vs Functions — Code, State, and the Instance
May 25, 2026 — Article 4 of the Studying TIA Portal series. The structural difference between Function Blocks (FB) and Functions (FC) — code that remembers vs code that forgets — and how the instance data block model carries state across calls. Includes a cross-platform comparison of how Siemens TIA Portal, Beckhoff TwinCAT 3, Codesys, and SIMATIC AX implement the same IEC 61131-3 split, plus a worked example of multi-instance FB design and the two Siemens download-without-reinitialization mechanisms (per-DB memory reserve since V12, V21 "Keep actual values" for S7-1500).
Multi-Instance vs Single-Instance Function Blocks in TIA Portal
December 5, 2025 — Learn why multi-instance function blocks in TIA Portal are better than single-instance for reusable, library-ready PLC code.
