Siemens SIMATIC S7-300 - Buy Now in the Shop

The SIMATIC S7-300 was introduced by Siemens in the early 1990s. Market launch took place around 1994 as the successor to the SIMATIC S5 series. It quickly became the standard PLC system in automation technology and was continuously expanded over many years. Today, the SIMATIC S7-300 series is therefore around 30 years old. 

Despite its age, the S7-300 is still widely used, which is also the reason why Siemens has scheduled a transition and support period until around 2033. 

1. Market launch (from around 1994) - initial release as the successor to the SIMATIC S5. Over the years, it was expanded with numerous CPUs, signal assemblies and communication processors.
2. Active marketing / full availability (1994 - approx. 2020s) - standard PLC in many industries. Deployed millions of times worldwide. Fully supported in STEP 7 (Classic).
3. Phase-out announcement (PM400) - October 2023: Siemens officially announces the product phase-out. Start of phase-out planning for customers.
4. End of new procurement - 1 October 2025: new orders for S7-300 / ET 200M components from Siemens will no longer be possible (only remaining stock, distributors or spare part inventories).
5. Spare part and service phase - Siemens guarantees spare part availability and technical support until at least 2033. Based on experience, key spare parts may still be available afterwards through third-party suppliers or remaining stock - however, at increasing prices and with growing risk.
6. Product phase-out (End of Service and Repair, EOSR) - expected after 2033, the SIMATIC S7-300 will reach End of Life (EOL). After that, only third-party service or replacement via the secondary market will be possible. 
    

Yes, Siemens is discontinuing production of the SIMATIC S7-300 / ET 200M components. The official product phase-out (Phase-Out, PM400) was initiated on 1 October 2023. The date from which no new S7-300 / ET 200M components can be ordered (Discontinuation, PM410) is 1 October 2025. After 1 October 2025, the manufacture of new components will come to an end. 

The official successor to the SIMATIC S7-300 and ET 200M is the SIMATIC S7-1500 in combination with the ET 200MP peripheral. The S7-1500 has been on the market since 2012 and was developed by Siemens specifically as a modern platform to carry forward the strengths of the S7-300 while at the same time meetings all the requirements of today's and future automation systems. 

The ET 200MP peripheral is the direct successor generation to the classic S7-300 assemblies, as well as the ET 200M assemblies. Since the S7-1500 CPUs are technically different from the S7-300 CPUs (new backplane, new slots, new power supply), the old S7-300 / ET 200M range with assemblies that are functionally very similar to the well-known S7-300 / ET 200MP assemblies, mechanically and electrically compatible with the S7-1500 design, and seamlessly integrated into the TIA Portal. 

The key difference between SIMATIC S7-300 and S7-1500 assemblies are:

 
Performance & memory
S7-300: Medium processing performance, limited memory, suitable for standard automation tasks. 
S7-1500: Significantly faster CPUs, more memory and short response times - also ideal for complex applications. 

Engineering & software
S7-300: Programmed traditionally with STEP 7 (Classic); in some cases also usable in TIA Portal, but with limitations. 
S7-1500: Programmed exclusively in TIA Portal, with a unified interface for PLCs, HMIs, drives and networks. 
 

Diagnostics & operation
S7-300: Diagnostics only possible to a limited extent, usually via external tools or operator panels. 
S7-1500: Integrated diagnostics, web server, plain-text messages and display directly on the CPU. 
 

Safety & technology
S7-300: Safety and technology functions only available with separate CPUs or additional assemblies. 
S7-1500: Safety (F-CPUs) and technology (e.g. motion control) are directly integrated into the CPU. 
 

Security (IT security)
S7-300: Hardly any integrated protection functions.
S7-1500: Comprehensive protection against unauthorised access, tampering and know-how theft.
 

Future viability
S7-300: Production phase-out until 2025, spare parts supply guaranteed until at least 2033. 
S7-1500: Current Siemens platform, available in the long term and continuously developed. 

For programming the SIMATIC S7-300, the standardised PCL languages according to IEC 61131-3 are used. Siemens implemented these in STEP 7 (Classic). The most important programming languages are: 

• KOP (Ladder Logic), graphical representation, based on electrical circuit diagrams.
• FBD (Function Block Diagram), also graphical, using logical function blocks.
• STL(Statement List, AWL), text-based language, similar to assembler, very flexible and often used for complex processes.
• SCL (Structured Control Language) (optional with add-on package), high-level language similar to Pascal, suitable for calculations and structured programming.
• SFC (Sequential Function Chart) (optional), language for modelling sequential steps and state transitions.
   

Yes, S7-300 and S7-400 controllers can in principle be programmed in the TIA Portal, but with certain limitations. Support began with TIA Portal V13 (around 2014). Not all older CPUs and assemblies are compatible. In particular, older assemblies that were already discontinued before the introduction of the TIA Portal. However, blocks, libraries or special functions often need to be adapted, as not everything can be transferred on a one-to-one basis. For new projects, Siemens still recommends migrating to the S7-1500, despite the compatibility of the S7-300 and S7-400 in TIA Portal, since only here the full range of TIA Portal functionality can be used without restrictions. 
 

• S7-300 CPU 312/313 → only partially usable in TIA Portal; many older CPUs are no longer supported.
• S7-300 CPU 314/315/317 → supported as of TIA Portal, but with restrictions on older hardware versions.
• S7-300 CPU 319 → well supported; migration into TIA Portal is possible
• S7-400 CPU 412/414 → supported as of TIA Portal V13, though not all communication processors are covered.
• S7-400 CPU 416/417 → generally supported, but with restrictions regarding special modules. 

Older special assemblies (e.g. Cx or older T-CPUs) → not supported in TIA Portal, only usable with STEP 7 Classic. 

The SIMATIC S7-300 and S7-400 both belong to the same generation of Siemens controllers, but they differ significantly in their intended purpose and performance.

The S7-300 was for many years the standard solution in machine and system engineering. It is particularly suitable for medium-sized automation tasks, such as in packaging machines, conveyor systems or assembly equipment. Its CPUs provide solid but limited processing performance and can be expanded in a modular way - though only within a manageable scope. Communication is usually via PROFIBUS or PROFINET, with additional modules required. 

The S7-400, on the other hand, was developed for larger and more complex applications, as found in the process industry (chemicals, energy, water/ wastewater, paper or steel systems). It features significantly more powerful CPUs, can handle far more inputs and outputs, and offers high scalability through large racks and numerous expansion options. A key difference is the possibility of using redundancy - that is, operating with duplicate CPUs or networks - which ensures very high system availability. Memory sizes and address ranges are also considerably larger in the S7-400 compared to the S7-300. While the S7-300 is aimed at medium-sized control tasks with moderate performance requirements, the S7-400 is designed for large, complex and critical systems where performance, scalability and reliability are crucial. 

Both systems are now in phase-out. For new projects and migrations, Siemens recommends switching to the S7-1500 (as successor to the S7-300) or, in combination with the PCS 7 process control system / S7-410, as a replacement for the S7-400.