S7-300 and S7-400 PLC Lifecycle Siemens Support Phases and Spares

Overview of Siemens SIMATIC Product Lifecycle Management

Siemens applies a four-stage Product Lifecycle Management (PLM) model to every automation component sold under the SIMATIC family, including the S7-300 and S7-400 PLC families. The PLM phases are documented in the official Siemens Industry Online Support entry SIMATIC Product Lifecycle Phases (entry ID 91688124) and are referenced whenever a part is purchased, quoted, or archived in the Siemens Mall (Industry Mall).

The PLM milestones are designated PM300, PM400, PM410, and PM490. They apply identically to CPUs, signal modules (SM), function modules (FM), communication processors (CP), power supplies (PS), interface modules (IM), and SIMATIC HMI accessories. When a project engineer asks "for how many years will Siemens provide support or spares for the S7-300 and S7-400," the correct technical answer is: up to 22 years from initial product delivery release — 12 years of active delivery plus 10 years of spare-part commitment. Field service life of properly maintained hardware frequently exceeds this window.

PM300: Active Product (Product Delivery Release)

PM300 marks the official start of normal commercial availability. From the PM300 milestone onward, the product is orderable through the Siemens Mall for up to 12 years (active selling phase). During PM300 the catalog is fully stocked, firmware updates are issued as needed, technical data sheets are actively maintained, and migration kits to successor families (e.g., ET 200SP or S7-1500) are typically offered.

PM400: Announced Phaseout

PM400 signals the end of the active selling phase and the beginning of a 10-year spare-part commitment period. From PM400 onward the product is no longer produced in volume, but new units in unopened original packaging are still available while warehouse stock lasts. Engineering changes are frozen except where safety-relevant corrections are required.

The PM400 announcement is the critical trigger for spare-part stocking decisions. Sites that depend on a specific S7-300 CPU or S7-400 CPU should place a final-volume order at this milestone, including any peripheral modules that share the same lifecycle bucket.

PM410: Product Cancellation (End of Production)

PM410 starts the dedicated spare-part phase. New production is stopped. The product can still be ordered, but only as a spare part with possible minimum-quantity rules, longer lead times, and—in some cases—replacement through refurbished (exchange) units. With few exceptions, marketing brochures, configurator entries, and the standard catalog are withdrawn.

PM490: Product Discontinuation

PM490 is the formal endpoint. The product is no longer available from Siemens, support is discontinued, and spare-part obligations expire. Documentation remains accessible as an archived entry, but no firmware patches, no corrections, and no exchange units will be supplied.

Aggregated Lifecycle Timeline

The maximum official support window for a single SIMATIC article number is therefore approximately 22 years from PM300, regardless of family (S7-300, S7-400, ET 200, HMI, SINAMICS, etc.).

Checking Lifecycle Status of a Specific Part Number

The lifecycle status of every MLFB (Siemens order number, e.g., 6ES7…) is published in two places:

1. Siemens Industry Online Support — support.industry.siemens.com → product search → entry for the article number.
2. Siemens Industry Mall — the price-and-availability lookup displays the PLM code (PM300 / PM400 / PM410 / PM490) directly on the product page.

Example part number:

Article Number:     6ES7315-2EH14-0AB0
Product Description: SIMATIC S7-300 CPU 315-2 PN/DP
Family:              CPU 315-2 PN/DP
Work memory:         384 KB
Interface 1:         MPI/DP 12 Mbit/s
Interface 2:         Ethernet PROFINET, 2-port switch
Media:               Micro Memory Card required
Product Lifecycle:   PM300 — Active Product

For a large site inventory, generate an accurate parts list (CPU + SM + FM + CP + PS + IM + HMI + cables + memory cards) and look up each MLFB individually. Mixed systems are common: an S7-300 CPU may still be PM300 while an older SM321 signal module on the same rack is already PM410. Procurement must respect the shortest remaining lifespan on the BOM.

S7-300 Lifecycle Considerations

The S7-300 family entered its PM300 active phase in 1994 (first generation CPU 312 IFM / CPU 313 / CPU 314) and is being phased out model-by-model as customers migrate to S7-1500 with ET 200SP. Successive CPU generations (e.g., CPU 315-2 PN/DP, CPU 317-2 PN/DP, CPU 319-3 PN/DP) have been moved through PM400 announcements in waves since roughly 2018.

Specific S7-300 lifecycle items to monitor:

• CPU 31x and 31xC series — early variants already reached PM410; later PN/DP variants are still PM300 or PM400.
• Micro Memory Cards (MMC) — most S7-300 CPUs from the 314 IFM era onward require an MMC; MMC part numbers have a separate lifecycle from the host CPU.
• Front connectors (6ES7392-…) — long PM300 lifespans but worth checking individually.
• Signal modules SM321 / SM322 / SM331 / SM332 — variants are split; e.g., 6ES7321-1BL00-AA0 may differ in lifecycle from 6ES7321-7BH01-0AB0.
• F-CPUs and F-modules — see dedicated section below for additional PFD/PFHD documentation.

S7-400 Lifecycle Considerations

The S7-400 family entered service in 1995 and has a longer generational tail than the S7-300. Siemens published a formal "SIMATIC S7-400 discontinuation of sale" announcement in waves starting in 2020, with most CPUs entering PM400 in 2020–2023. The standard 10-year spare-part commitment therefore runs into the 2030–2035 window for typical S7-400 installations. AS 410 single stations and AS 410H / AS 400H redundant stations share a common lifecycle but each MLFB is checked individually.

Specific S7-400 lifecycle items to monitor:

• CPU 412, 414, 416, 417 series — base variants and PN/DP variants have separate lifecycles.
• CP 443-1 / CP 443-5 Extended — these communication processors are decoupled from the CPU lifecycle and may remain PM300 longer.
• PS 405 / PS 407 power supplies — typically share the longest PM300 windows; check 10 A / 20 A variants separately.
• F-modules (F-CPU, F-SM, F-DO) — see dedicated section below.
• Memory cards (RAM, Flash, MC) — storage media have shorter practical lifespans than the host PLC and should be replaced preventively.

S7-300 / S7-400 Migration Path to S7-1500

Siemens provides explicit migration tooling and successor families for both S7-300 and S7-400:

The migration is non-trivial: STEP 7 V5.x projects must be converted to TIA Portal, I/O wiring must be remapped, and PROFIBUS DP slaves (on the S7-300/400) are commonly replaced with PROFINET IO devices (on the S7-1500). Plan migration windows in advance of PM410 to avoid rush engineering.

Special Note on F-Modules: PFD and PFHD Parameters

Fail-safe (F-) CPUs and F-modules carry additional lifecycle-relevant parameters: PFD (Probability of Failure on Demand) and PFHD (Probability of dangerous Failure per Hour). These values are used to calculate the safety integrity level (SIL) of a safety loop and are documented separately from the standard PLM phase. Refer to the official FAQ Which values can you use with F-CPUs and products of the ET 200 family for PFD and PFHD? for the latest numerical table.

Important: PFD/PFHD values are valid for the certified mission time (typically 20 years) and may be revised if the module firmware is updated. Safety lifecycle parameters are unrelated to the PM300/PM400 commercial lifecycle — a module may be PM410 commercially and still have a valid PFD/PFHD certificate, or vice versa.

Field Operating Life vs. Siemens Support Life

The Siemens PLM timeline governs Siemens' commercial support. The actual field operating life of an S7-300 or S7-400 depends on environmental conditions:

Field reports confirm that S5-115U PLCs installed in the 1980s are still operational in 2024 in well-controlled factory environments. S7-300 and S7-400 hardware has equivalent or better MTBF ratings and is expected to operate for 15–25+ years on the factory floor if maintained correctly. However, operating beyond PM490 means no Siemens spare-part guarantee; the operator assumes all obsolescence risk.

Spare-Part Planning Strategy

1. Inventory every MLFB in the control cabinets, including CPUs, SMs, FMs, CPs, PSs, IMs, HMI panels, and cables.
2. Pull lifecycle status for each MLFB from the Siemens Industry Online Support portal or the Industry Mall.
3. Classify each item by minimum remaining years to PM490.
4. Stock critical spares at PM400 — typically 1× CPU of each type, 10–15 % of the SM population, 1× of every CP and FM, plus all firmware-loaded memory cards.
5. Schedule migration before PM410 to avoid rush engineering; build the new S7-1500 system on TIA Portal V17 or later and validate in parallel with the running S7-300/S7-400.
6. Archive programs and project files on durable media; the STEP 7 V5.x project for the legacy system is the only path to firmware-equivalent operation if a CPU swap is needed.
7. Track F-module mission time separately; replace F-CPUs and F-SMs before their 20-year PFD/PFHD mission time expires, independent of PLM.

Environmental and Storage Notes

Frequently Asked Questions