How to convert an S7-300 program to S7-1500 in TIA Portal (step by step)

Updated: 24 October 2026 · SIM Solutions

Short answer

Convert an S7-300 program to S7-1500 in TIA Portal in six steps: archive the STEP 7 project (V5.4 SP5 or later) and remove know-how protection; migrate it into TIA Portal with "Migrate project"; right-click the CPU and choose "Migrate to S7-1500"; configure the new hardware and network again, because I/O modules and network devices are not carried over; fix what does not convert, such as ALARM_S, ALARM_SQ and ALARM_SC (use Program_Alarm), clock functions and CBA; then compile and test in S7-PLCSIM Advanced before commissioning. Siemens also offers a separate Migration Tool for migrating without TIA Portal installed.

Why now

Siemens states that the S7-300 and ET 200M families entered phase-out on 1 October 2023 and have been supplied only as spare parts since 1 October 2025, with no orders from 1 October 2033. See S7-300 end of life for the dates and how to plan a site-wide programme.

Before you start

The STEP 7 source project must be STEP 7 V5.4 SP5 or later. Older projects are first opened and saved in a newer STEP 7 version.
Remove know-how protection from blocks; protected blocks cannot be migrated.
Install the GSD files of third-party devices in TIA Portal.
Make a full backup and check that the offline project matches what runs in the CPU.

The steps in TIA Portal

Migrate the project. In TIA Portal, use Project › Migrate project to bring the STEP 7 project in. Read the migration log.
Migrate the CPU. Right-click the S7-300 CPU and choose "Migrate to S7-1500". TIA Portal converts the program for the new CPU family.
Rebuild hardware and network. Configure the S7-1500 rack, distributed I/O and network again; I/O modules and other network devices are not migrated automatically.
Fix what does not convert. ALARM_S, ALARM_SQ and ALARM_SC are not supported on S7-1500; replace them with Program_Alarm. Clock and date/time functions differ. CBA is not supported. Review every warning in the log.
Compile and test. Compile, then test the program in S7-PLCSIM Advanced against test cases from the functional description, including interlocks and modes.
Commission. Plan the cutover in a stop, with the S7-300 and its program kept as fallback until sign-off.

Decisions the tool cannot make for you

Keep the old structure, or restructure to a modern standard with optimised blocks and libraries.
Replace ET 200M with ET 200SP or keep it as distributed I/O during a transition.
Migrate the HMI at the same time (for example to WinCC Unified or Ignition) or later.

Where AI helps

AI reads the old program and writes the functional description that is often missing, lists every block the migration log flags, drafts replacements for unsupported instructions and generates test cases for S7-PLCSIM Advanced. An engineer reviews and tests everything. See our AI toolkit and how to document a legacy PLC with AI.

Questions we get

Can TIA Portal migrate a STEP 7 V5.x project automatically?

It migrates the project and converts the program, but hardware, networks and some instructions need engineering work. Treat the result as a starting point to review and test.

Can I migrate without TIA Portal installed?

Siemens offers a separate Migration Tool for that. The final conversion to S7-1500 is done in TIA Portal.

What about S7-400 and PCS 7?

Those follow other migration paths and are not covered by the S7-300 to S7-1500 guide.

Do we need to replace the I/O?

Not always on day one. Many plants keep ET 200M distributed I/O for a while and replace it later; the spare-parts dates decide how long that is wise.

How to convert an S7-300 program to S7-1500 in TIA Portal