Sooner or later every S7-300/400 plant faces the question: stay on STEP 7 Classic until the hardware dies, or migrate to TIA Portal on your own schedule. Having done both — planned migrations and panic migrations after a CPU failure — we strongly recommend the first.
What the migration tool actually converts
TIA Portal’s built-in migration handles more than most people expect: hardware configuration (for supported modules), symbol tables, LAD/FBD/STL blocks and most of the block calls arrive intact. What does not survive cleanly:
- Absolute addressing habits. Classic projects full of direct M-area flags migrate, but you lose the chance to move to optimized blocks unless you refactor.
- STL-heavy code. STL still runs on S7-300/400 targets in TIA, but S7-1500 CPUs execute it in a compatibility mode that costs performance — and some pointer tricks simply fail.
- Third-party OPs and old WinCC flexible panels. Panel projects usually need rebuilding rather than migrating, and old Basic Panels cap your WinCC version.
The plan that works
Migrate the project in the office first, months before touching hardware. Compile, fix, and run it against PLCSIM. Keep the plant on the old CPU until a planned stop, then swap CPU and download the tested project. The migration itself is a day of work; the testing is where quality happens. Budget 5–10 times the migration effort for testing and you will not be surprised.
Do not combine the migration with functional changes. One variable at a time: same behavior on new tools first, improvements second.
FAQ
Can I migrate directly from S7-300 to S7-1500? Yes, TIA offers a device replacement path, but plan a code cleanup: S7-1500 rewards optimized blocks and symbolic addressing, and punishes old pointer arithmetic.
Do I lose my comments? Network comments and symbols migrate. Comments living only in printouts or the programmer’s head do not — capture that knowledge before the person retires, not after.
Zone Otomasyon has migrated production lines from STEP 7 Classic to TIA Portal without unplanned downtime. Planning one? Talk to us.