PLC · 9 min read · Updated October 2026
Siemens S7-300 End of Life: Key Dates, Spare Parts and Migration to S7-1500
The S7-300 has entered its phase-out. New components are no longer the default, spare parts have a horizon, and every plant still running S7-300 needs a plan. Here is what the dates mean, which spares to secure now and how to migrate without a long shutdown.
S7-300 end of life is no longer a future event. Siemens set the product phase-out announcement for the SIMATIC S7-300 system and the ET 200M distributed I/O system on 1 October 2023. New components were available until 1 October 2025; after that, the range is supplied as spare parts, which Siemens plans to provide until at least 1 October 2033. For a controller family that runs thousands of machines and process lines worldwide, that changes how maintenance and investment should be planned.
Key dates at a glance
| Date | Milestone for S7-300 / ET 200M | What it means for you |
|---|---|---|
| 1 Oct 2023 | Product phase-out announced | Start planning: list installed systems and critical spares |
| 1 Oct 2025 | End of new-component delivery | Supply shifts to spare parts; availability and lead times become less predictable |
| Until at least 1 Oct 2033 | Spare parts planned | Keep lines running with spares while you migrate in stages |
Dates as published in Siemens' phase-out information for S7-300 and ET 200M. Always confirm the status of a specific order number with the manufacturer or your supplier.
What S7-300 end of life means in practice
- Spares get harder to find. As distributor and factory stock runs down, popular modules — CPUs, power supplies, interface modules and common I/O cards — are the first to become scarce.
- Prices and lead times rise. Plants that wait until a CPU fails usually pay the most and wait the longest.
- Know-how ages too. SIMATIC Manager (STEP 7 V5.x) skills and spare programming PCs are becoming as rare as the hardware.
- The risk is concentrated. One failed CPU without a spare can stop a whole line, while the rest of the I/O keeps working for years.
Option 1: secure the critical spares now
Even if a migration is planned, every running S7-300 system should have a minimum spare kit on the shelf. Prioritise by impact, not by price:
- CPU — one per CPU type in the plant, with the same or a compatible firmware version.
- Memory card — S7-300 CPUs of the newer generation run from a SIMATIC Micro Memory Card (MMC); keep a spare card with a current program backup.
- Power supply modules and interface modules (IM) for racks and ET 200M stations.
- Communication modules used for PROFIBUS, PROFINET or serial links to drives and other systems.
- The I/O cards that fail most often in your plant — usually digital outputs and analog inputs in harsh areas — plus front connectors.
When new stock is no longer available, spares come from remaining distributor stock and the surplus market. Insist on documented origin: authentication matters more for end-of-life parts than for any other product. Our obsolete parts service searches three layers of stock in parallel and only offers parts that pass traceability checks.
Option 2: staged migration to S7-1500
The direct successor of the S7-300 is the SIMATIC S7-1500, engineered in TIA Portal; distributed I/O moves from ET 200M to ET 200SP. A staged migration spreads cost and downtime:
- Stage 1 — controller first. Replace the S7-300 CPU with an S7-1500 and migrate the program. S7-1500 CPUs with a PROFIBUS DP interface, or a DP communication module, can continue to communicate with existing ET 200M stations, so field wiring stays untouched.
- Stage 2 — I/O by area. Replace ET 200M stations with ET 200SP during planned shutdowns, one area at a time.
- Stage 3 — HMI and networks. Move panels and SCADA connections to the new controller and, where useful, from PROFIBUS to PROFINET.
For small, simple machines, an S7-1200 can be a cost-effective alternative — but check memory, I/O count, communication and performance against the existing application first.
Migrating the program: what to expect
An S7-300 program does not run on an S7-1500 as it is: the project must be migrated from STEP 7 V5.x into TIA Portal and then adapted. Siemens publishes a migration guide for S7-300/S7-400 to S7-1500 and tools to check whether a STEP 7 V5.x hardware configuration is ready for migration. In practice, plan time for:
- System functions and blocks (SFC/SFB) that have different or newer equivalents on S7-1500.
- Indirect addressing and pointer code, which often needs rework, especially with optimised block access.
- Communication — serial point-to-point, PROFIBUS and S7 connections need to be re-checked and sometimes re-engineered.
- Timing and scan behaviour — faster CPUs can expose race conditions that were hidden before.
- HMI projects that must move to the TIA Portal environment as well.
- Testing — a simulation or factory acceptance test before cut-over shortens the shutdown dramatically.
A migration planning checklist
- Inventory every S7-300 system: CPU type, firmware, I/O count, networks, connected HMIs and drives.
- Collect and back up the latest programs from the running CPUs, not from old engineering PCs.
- Rank systems by production impact and by spare-part risk.
- Buy a minimum spare kit for every system that will run beyond the next 12–24 months.
- Choose the target architecture (S7-1500 + ET 200SP, or S7-1200 for small machines).
- Migrate and test the program offline, with simulation where possible.
- Plan cut-over in planned shutdowns, with a tested fallback to the old CPU.
How HOANTRANTDH helps
We work from Hai Phong, Vietnam, for plants in Vietnam and abroad: we source S7-300 spares through our obsolete parts network with an answer within 48 hours, supply S7-1500 and ET 200SP hardware, and our engineers carry out PLC migration and commissioning. Send us your list of order numbers through the quote form and we will check spares and migration options together.
Frequently asked questions
Is the Siemens S7-300 discontinued?
The S7-300 and ET 200M are in the phase-out process. Siemens announced the phase-out for 1 October 2023, new components were available until 1 October 2025, and spare parts are planned until at least 1 October 2033.
Can I still buy S7-300 parts?
Yes, as spare parts and from remaining stock. Availability differs by order number, so check critical parts early and make sure their origin is documented.
Can an S7-300 program run on an S7-1500?
Not directly. The STEP 7 V5.x project has to be migrated into TIA Portal and adapted, for example system functions, indirect addressing and communication.
Do I have to replace the ET 200M I/O at the same time?
No. In a staged migration, an S7-1500 with a PROFIBUS DP interface or DP module can keep communicating with existing ET 200M stations while the I/O is replaced area by area later.
Is S7-1200 a replacement for S7-300?
For small, simple machines it can be. For larger or process applications the S7-1500 is the usual successor; compare memory, I/O, communication and performance first.