Siemens 6ES7951-0KE00-0AA0 Flash Memory Card – SIMATIC S7-300

Siemens 6ES7951-0KE00-0AA0 — 32KB Flash Memory Card for SIMATIC S7-300 Control Systems

The 6ES7951-0KE00-0AA0 is a non-volatile Flash EEPROM memory card manufactured by Siemens AG for the SIMATIC S7-300 programmable controller platform. Within the S7-300 control architecture, this module occupies the memory card slot on the CPU front face and serves as the primary persistent storage medium for user programs (OBs, FBs, FCs, DBs) and system configuration data. Unlike battery-backed RAM modules used in earlier S5 generations, the Flash-based design of the 6ES7951-0KE00-0AA0 eliminates the dependency on a backup battery for program retention, making it operationally suitable for installations where periodic battery maintenance is impractical or prohibited by safety protocols.

At 32 KB of usable Flash capacity, this card targets S7-300 CPU variants whose user program footprint falls within the lower memory tier — typically compact automation cells, standalone machine controllers, and distributed I/O nodes running structured control programs of moderate complexity. The card interfaces with the CPU via the standard S7-300 memory card slot, which uses a proprietary Siemens connector geometry incompatible with commercial MMC or SD form factors, ensuring that only certified Siemens memory modules can be inserted, thereby preventing accidental use of uncertified media in safety-relevant control loops.

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Technical Parameters

Hardware Logical Analysis

The 6ES7951-0KE00-0AA0 integrates into the S7-300 CPU’s internal memory management architecture at the hardware level. When the CPU powers up, the firmware boot sequence reads the memory card’s content into the CPU’s internal load memory space before transferring executable code into work memory (RAM). This two-stage load process — load memory → work memory — is a deliberate architectural decision by Siemens to separate persistent storage from execution-speed-optimized RAM, allowing the Flash card to operate at its native read latency without impacting the CPU’s scan cycle determinism.

EMC Design Considerations: The S7-300 memory card slot is shielded within the CPU housing, which provides a degree of electromagnetic isolation from the backplane bus signals. The card’s Flash controller operates at low clock frequencies relative to the CPU’s main oscillator, minimizing radiated emissions from the memory interface. Siemens specifies the S7-300 platform to EN 61000-6-2 (industrial immunity) and EN 61000-6-4 (industrial emissions), and the memory card, as an integral CPU component, is covered under these certifications when installed in a compliant enclosure.

Write Protection and Data Integrity: The Flash EEPROM cells in the 6ES7951-0KE00-0AA0 implement hardware-level write protection during normal CPU run mode. Program writes to the card occur exclusively during STOP mode download operations initiated by STEP 7 or TIA Portal, preventing accidental overwrite of the user program during active process control. The card’s controller also implements internal error correction logic to maintain data integrity across the rated write cycle count, which is consistent with Siemens’ industrial-grade Flash specifications for the S7-300 memory card family.

Slot Interlock Mechanism: The proprietary connector geometry of the S7-300 memory card slot provides a mechanical interlock that prevents card removal while the CPU is in RUN mode on certain CPU variants. This design reduces the risk of program loss due to accidental card ejection in high-vibration industrial environments such as press lines, compressor stations, and mobile machinery.

System Integration Benefits

• Battery-Free Program Persistence: Flash EEPROM retains the full user program and all data blocks across power cycles without requiring a backup battery, eliminating a maintenance variable in long-lifecycle installations.
• Deterministic Boot Sequence: The CPU’s firmware loads the program from the Flash card into work memory in a fixed, predictable sequence, ensuring consistent startup behavior across power cycles — critical for safety-instrumented systems and process restart protocols.
• STEP 7 / TIA Portal Native Compatibility: The card is recognized natively by both STEP 7 v5.x and TIA Portal without additional drivers or configuration, enabling direct online download, memory reset, and card copy operations from the programming environment.
• Simplified Spare Parts Management: A single 6ES7951-0KE00-0AA0 card can serve as a complete program backup medium — a replacement CPU can be brought online by inserting the card and powering up, without requiring a programming device on-site.
• Reduced Commissioning Time: For multi-unit machine lines with identical S7-300 CPU configurations, the memory card enables rapid replication of the control program across multiple CPUs without repeated STEP 7 download sessions.
• Diagnostic Transparency: The S7-300 CPU reports memory card status (present / absent / write-protected / incompatible) via system diagnostics accessible in STEP 7 and TIA Portal, providing clear fault isolation without physical inspection of the card slot.
• Vibration and Shock Tolerance: Flash EEPROM has no moving parts and no battery electrolyte, making the 6ES7951-0KE00-0AA0 inherently more tolerant of mechanical shock and vibration than battery-backed SRAM modules used in earlier PLC generations.
• Scalable Upgrade Path: If program size grows beyond 32 KB due to added functionality, the S7-300 platform supports direct card replacement with higher-capacity variants (64 KB, 128 KB, 256 KB, 512 KB, 2 MB) without CPU hardware changes, protecting the existing control system investment.

Quality Assurance & Global Logistics

Every 6ES7951-0KE00-0AA0 unit supplied by siemensplc.com is sourced as genuine Siemens original product. Each unit undergoes a structured pre-dispatch verification process: physical label authentication against Siemens’ current part marking standards, connector and housing integrity inspection, and ESD-safe packaging in anti-static bags with moisture barrier sealing for long-haul air freight.

Dispatch operations are based in Xiamen, China — a major logistics hub with direct access to international air cargo routes serving Europe, North America, Southeast Asia, the Middle East, and Australia. Standard shipment lead times from Xiamen are 3–7 business days to most destinations via DHL Express, FedEx International Priority, or UPS Worldwide Express, depending on destination customs clearance conditions. For urgent plant-down situations, same-day dispatch is available for orders confirmed before 14:00 CST. All shipments include full tracking, commercial invoice, and packing list documentation. Export compliance documentation (including HS code classification and country of origin certification) is provided upon request for regulated procurement environments.

A 12-month warranty covers all units against manufacturing defects. In the event of a confirmed defect, replacement or credit is processed within 5 business days of return receipt and inspection. Technical support for installation, compatibility verification, and STEP 7 / TIA Portal configuration is available via email and WhatsApp at no additional charge.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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