If there is one PLC family that has defined three decades of global manufacturing, it is the SIMATIC S7-300. Since its debut in the 1990s, the S7-300 — together with its high-end counterpart, the S7-400 — has been the backbone of factory control rooms, production-line cabinets, and process automation systems worldwide.
But times change. Siemens has officially initiated the product phase-out process for both the S7-300 and S7-400 series. For the thousands of factories still relying on these legendary controllers, this is a signal that demands immediate attention.
This guide is compiled from Siemens' official lifecycle documentation (verified August 2026):
Data provenance and transparency (read this first). The information in this guide falls into three categories: ① Official lifecycle status — from Siemens' official support documents and product pages (links in the Sources section); status is stated "as of August 2026," and for specific models always check Siemens' official lifecycle query. ② Market observations — eBay premiums and extended lead times are observations from secondary-market platforms and channel partners in mid-2026; they are market signals, not statistical survey data. ③ Migration advice — based on Siemens' official migration guide and our own project experience serving customers. We are an industrial automation distributor supplying Siemens original spare parts, migration solutions, and alternative brands (including some Chinese brands); recommendations reflect application fit and customer needs, not purely commercial terms.
Siemens follows a standardized SIMATIC lifecycle management process. Here are the critical milestones and the current status of the S7-300/S7-400:
| Stage | Meaning | S7-300 / ET 200M Status (as of Aug 2026) | S7-400 Status (as of Aug 2026) |
|---|---|---|---|
| Active | Full production, all variants available | ❌ Closed | ❌ Largely closed |
| Phase-Out announcement (PM400) | Removed from active marketing; enters exit process | ✅ Entered on Oct 1, 2023 | ✅ In progress |
| Discontinuation (PM410/PM140) | New production stops; spare-parts/repair channels only | ✅ Effective Oct 1, 2025 (confirmed by Siemens) | Taking effect model by model |
| Spare Parts | Available only through spare-part channels at premium pricing | ⏳ In progress (industry interpretation: expected at least until Oct 2033) | In progress |
Key facts (based on Siemens' official documentation, as of August 2026):
Important: the status of a specific model (orderable / discontinued / spare-parts phase) varies — not all models phase out on the same date. Check each model individually via the Siemens TIA Selection Tool or the official support portal.
As a reference point, Siemens has announced that the S7-1200 (G1) family will officially enter phase-out on November 1, 2026 (orderable as a new part until September 30, 2027, per Siemens' official advance notice). Against that backdrop, the S7-300/400 discontinuation is triggering an even larger wave of market disruption. Mid-2026 market observations:
Our advice: the used/refurbished market is only for emergency scenarios with a clear risk appetite; for critical lines, prioritize locking in original spare parts. (For the full Q&A on refurbished-module risk, see FAQ Q3 at the end of this guide.)
Factories under phase-out pressure typically have three strategic options. We break down the pros and cons of each.
(For the full Q&A on migration workload, see FAQ Q2 at the end of this guide.)
Need help? We can assist with the asset-audit template, spare-parts locking, and migration-plan evaluation (contact details at the end of this guide).
Q1. After the S7-300 is discontinued, can I still buy spare parts, and for how long?
Yes. According to Siemens' official lifecycle documentation and industry interpretation of its 10-year spare-parts policy, the S7-300/ET 200M entered the spare-parts phase on October 1, 2025, expected to last until at least October 2033. Spares are only available through spare-part channels at rising prices, and some models may run out early — which is why we recommend locking in stock of critical models now. Check each model's status on Siemens' official lifecycle pages.
Q2. Can my S7-300 programs be migrated to the S7-1500, and how much work is involved?
Yes. Siemens' official S7-300/S7-400 to S7-1500 migration guide states that Step 7 V5.x programs can basically all be migrated to TIA Portal, with CPU cross-reference tables (e.g., 315-2 DP to 1515-2 PN). The workload depends on special instruction blocks, hardware configuration changes, and program standardization. The migration tools are mature, but hardware replacement, rewiring, and on-site commissioning verification are the main effort. We recommend a pilot line first, then rollout.
Q3. Can I buy used or refurbished S7-300 modules? How do I reduce the risk?
Yes, for emergency use, but control the risk. Refurbished modules have unknown repair history, firmware versions, and component aging. If you buy, require source documentation and test records, verify firmware compatibility, test on a bench before installation, and use them only on non-critical stations. Refurbished units suit emergencies, not long-term solutions for critical lines.
Q4. Are there alternatives to Siemens, such as Chinese PLC brands?
Yes, but evaluate rationally. Two routes: migrate within the Siemens ecosystem (S7-1500/ET 200SP, best program compatibility), or third-party/Chinese alternatives (usually lower cost, but check programming environment, PROFINET/PROFIBUS compatibility, safety certifications such as CE/UL, and spare-parts and support networks). As a distributor, we supply both Siemens spare parts and migration solutions and Chinese brands like INVT — let your requirements decide: send us your I/O list, protocols, and budget for a 2–3 tier comparison.
Q5. What is the most urgent thing to do right now?
Follow the 5-step checklist in priority order: 1) asset audit (inventory all S7-300/400 modules with MLFB, quantity, and location); 2) mark critical modules whose failure would stop the line; 3) lock in spare-part channels within about 2 weeks — prices and lead times only get worse; 4) create a migration schedule in 6-month phases by line priority; 5) verify HMI/SCADA compatibility with the target platform.
The S7-300/400 phase-out is not something that "will happen" — it is already underway: the S7-300 was formally discontinued on October 1, 2025, the S7-400 is exiting model by model, and the spare-parts phase is expected to last until around 2033. For factories still running these platforms, now is the critical window to decide between "stock spares and ride out the transition" and "plan the migration."
Whichever path you choose, the core principle is the same: audit first, lock in parts second, plan third. The cost of delay is certain — rising spare-part prices, longer lead times, and fewer available models.
How we can help: we supply S7-300/400 original spare parts (including locking in scarce models), provide S7-1500/ET 200SP migration plans and budget estimates, and can offer Chinese-alternative comparisons on request. For an asset-audit template, spare-part pricing, or migration consulting, contact us — our engineering team provides 1-on-1 service.
Shanghai Fradwell Industrial Automation Co., Ltd is a leading global supplier of high-performance industrial automation solutions, dedicated to connecting global buyers with high-quality Chinese automation solutions.
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