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Migrating S7-300 and S5 to S7-1500: When, How, and Can It Fit One Shutdown?

Since 1 October 2025, SIMATIC S7-300 and ET 200M have been in Siemens lifecycle phase PM410: no new orders, supply in spare-part quantities only. S5 has been out of manufacturer support for years. This guide helps you decide whether to stock spares or migrate to S7-1500 now, and how to fit the cut-over into one planned shutdown.

Author: Piot Engineering technical teamPublished:

An open control cabinet: an older, bulky PLC with its I/O modules on the upper rail, a new compact PLC on the lower rail, and an I/O list on a clipboard inside the door.

What changed for the S7-300 in October 2025?

The SIMATIC S7-300 and ET 200M families have been in Siemens lifecycle phase PM410 since 1 October 2025. They are no longer sold for new projects or extensions, only in spare-part quantities. Siemens announced the phase-out (PM400) in October 2023. The successors are the S7-1500 CPUs with the ET 200MP and ET 200SP I/O systems.

In practice, three things are different now:

  • No new procurement or extensions. Adding modules to a running line, or building another copy of a machine on S7-300, is no longer something you can plan around.
  • Parts arrive as spare parts. You can still buy a module to replace a failed one like for like, but stock and lead time are not guaranteed.
  • Prices are going up. As with earlier phase-outs, Siemens is expected to raise spare-part prices noticeably, citing storage, production and logistics costs.

How long will S7-300 spare parts be available?

Siemens' S7-300 product page states that the S7-300/ET 200M families will be available until 2033. That matches the rule industry sources describe: Siemens counts its ten-year spare-parts commitment from the phase-out announcement (PM400), so October 2023 plus ten years.

Two caveats. "Available" does not mean available at today's price and lead time. And status and dates can differ by order number. Rather than relying on a single date, check each critical module in your plant against the Siemens online catalogue (Industry Mall) and the notices on Industry Online Support.

Where does the S5 stand?

For SIMATIC S5 there is no timeline left to discuss. In the Siemens online catalogue, S5 modules show status PM500, end of product lifecycle and support, reached between 2013 and 2022 depending on the module. Industry sources confirm that Siemens no longer supplies spare parts or repairs for S5. Today S5 parts come only from the second-hand and refurbished market.

An S5 line usually carries a knowledge risk as well. Whoever wrote the program left long ago, few maintenance technicians still read STEP 5, and the old programming device and software needed to go online are not in every plant. When it fails, the length of the stoppage depends on whether a tested spare is on the shelf.

Stock spares or migrate now?

The answer depends on three things: how critical the line is, the state of your program backups and documentation, and the planned shutdowns ahead of you. The table below is a starting framework.

Your situation Reasonable course
If the line stops, shipments stop, and production can't move to another line Put the migration into the first suitable shutdown; until then, keep tested spares for critical modules
The machine will be retired within a few years anyway Stocking tested spares is often enough
The same CPU and modules run on many machines Build a shared spares pool and migrate machine by machine
No current, verified program backup exists Whatever you choose, take and document a backup first
No long enough shutdown in the next 12 months Finish the engineering now and tie the cut-over to the first long window
A capacity increase or change to the line is planned Don't build the change on S7-300; combine it with the migration

One rule: a spare is only a spare if it has been tested. An untested CPU or second-hand module on the shelf is worth nothing if it doesn't start on the night of the breakdown.

How does the migration work, step by step?

A PLC migration comes down to four jobs: record what you have, map it to new hardware, move the program, and test all of it before the shutdown. Siemens' own migration guides follow the same order: inventory and analysis first, then strategy and fallback planning, commissioning last.

  1. Backup and documentation. Take an online backup of the program running in the CPU and compare it with the project file you have. Check the cabinet drawings against the real wiring.
  2. I/O list. List every input and output with address, signal type, connected field device and terminal number. This list is the backbone of the project.
  3. Hardware mapping. Pick the S7-1500 CPU to replace the S7-300, ET 200MP for central I/O and ET 200SP for distributed I/O. Siemens' mapping tables are a starting point; check voltage, current and channel count module by module. S7-300 modules don't fit an S7-1500 rail, but Siemens' Interface Module Adapters connect the existing front-connector wiring to the new modules. Compatible remote ET 200M stations can stay in place in a first phase.
  4. Moving an S7-300 program. A project that compiles without errors in STEP 7 V5.x is migrated into TIA Portal and then moved to the new CPU with the "Migrate to S7-1500" function. Hardware configuration and program blocks come across. Some system functions and message blocks (ALARM_S, for example) are not supported on S7-1500, FM modules are replaced by technology objects, and there is no MPI interface. These are fixed by hand, and the migrated program must be tested.
  5. Moving an S5 program. Siemens' path is the S5/S7 converter in STEP 7 V5.5 first, then TIA Portal. The converter carries over most of the code, but it comments out instructions with no IEC equivalent and flags them as errors. The functions of system blocks such as DB0, DB1 and DX0 move into the hardware configuration, and special OBs from OB110 upwards have to be rewritten. In practice an S5 migration is engineering, not conversion. On many projects a structured rewrite is faster and safer than cleaning up converted code.
  6. HMI and drives. Old operator panels connected over MPI or PROFIBUS are usually replaced, because communication and alarm handling change. Ask the same question for drives: end-of-life families such as MASTERDRIVES carry the same spare-part problem.
  7. Test before the shutdown. Run the program on a PC without hardware using S7-PLCSIM or S7-PLCSIM Advanced and work through the scenarios one by one. Test the new cabinet's I/O in the workshop. The goal is to arrive on site only for mounting, connection and signal checks.
  8. Cut over in a planned shutdown. In Turkey these windows are typically the bayram (public holiday) breaks, year-end and the summer shutdown; elsewhere it is usually Christmas and summer. Write the plan hour by hour and fix the fallback time in advance.
  9. Commissioning and handover. Signal checks first, then dry runs without product, then production with real parts. At handover you get the current project file, I/O list, cabinet drawings and a backup copy of the program together.

Can it fit one shutdown?

For most S7-300 migrations, yes. For S5, only if all engineering and testing is finished before the shutdown starts. The shutdown window is for installing a system that has already been tested, not for writing the program.

Two tools lower the risk. The first is a phased migration: Siemens' S7-300 guide explicitly describes replacing the CPU first while keeping compatible peripherals, and leaving the full move to ET 200MP or ET 200SP for a second step. The second is a fallback plan: the old CPU and modules are not thrown away but labelled and shelved. If the new system isn't ready for production by the agreed hour, you go back to the old one.

Safety programs are a topic of their own. When a safety program from an S7-300F is moved to an S7-1500F and compiled, its collective F-signature changes, and as Siemens states, the safety program then needs a new acceptance. Put that validation into the schedule from the start.

Where do migrations usually go wrong?

  • Undocumented changes. The program running in the CPU may not be the project file you have. Years of small changes on the shop floor only show up in an online comparison.
  • Forgotten field devices. A sensor outside the cabinet, a measuring instrument or a single signal from another machine that isn't on the I/O list will be missing on commissioning night.
  • Communication partners. Other PLCs, robots, SCADA, barcode readers and old serial links all need to be listed. Older networks such as MPI and SINEC L1 don't exist on S7-1500.
  • Safety circuits. Emergency stops, door interlocks and light curtains are tested one by one on the new system before the line goes back into production.
  • No fallback plan. If neither the new nor the old system can run on Monday morning, the shutdown is no longer planned.

Checklist

Step What must be ready When
Program backup Online backup, compared with the project file First week
I/O list Address, signal type, field device, terminal Start of engineering
Communication list Networks, partner devices, protocols Start of engineering
Hardware list S7-1500 CPU, ET 200MP / ET 200SP, adapters, HMI, drives Early, based on lead times
Program Migrated or rewritten, compiled, reviewed Before the shutdown
Simulation test Scenario tests in PLCSIM Before the shutdown
Cabinet test I/O test in the workshop Before the shutdown
Safety validation Validation plan and forms Inside the shutdown plan
Shutdown plan Hour-by-hour plan, owners, fallback time At least two weeks before
Handover Current project, drawings, I/O list, backup copy After commissioning

How Piot helps

We migrate SIMATIC S5 systems to S7-1500 and replace end-of-life drives with current series. The scope is described on our PLC migration page, and after the cut-over our PLC, HMI and SCADA support is available 24/7. The first step is a free site visit: we look at your cabinet and program together and answer the spares-or-migrate question with data from your own line.

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