Siemens SIMATIC S7-300 Memory Cards: 6ES7951-0KE00-0AA0

Technical Dossier

Product Details And Specifications

Siemens SIMATIC S7-300 Series: Comprehensive Memory Module Range and Technical Overview

The Siemens SIMATIC S7-300 is one of the most widely deployed programmable logic controller (PLC) platforms in global heavy industry. Installed across petrochemical refineries, nuclear power auxiliary systems, offshore platforms, steel mills, and pharmaceutical batch processing facilities, the S7-300 has maintained a dominant position in process automation since its commercial introduction in the early 1990s. The memory card subsystem — referenced under the 6ES7951-xxxx-xxxx product family — is a critical consumable component within this architecture, responsible for storing user programs, data blocks, and firmware images independently of the CPU's volatile RAM. The 6ES7951-0KE00-0AA0 specifically is a 32KB Flash Memory Card designed for use with S7-300 CPU modules, providing non-volatile program retention without battery dependency.

The Evolution of S7-300 Memory Card Architecture

The S7-300 memory subsystem has undergone three distinct architectural generations since platform launch. In the initial release (circa 1993–1998), program storage relied on EEPROM-based memory cards with limited write-cycle endurance and capacities ranging from 16KB to 256KB. These early cards used a proprietary Siemens card form factor incompatible with standard PCMCIA or CompactFlash standards, a deliberate design choice to enforce platform integrity in safety-critical environments.

The second generation (1999–2008) introduced Flash-based memory cards under the 6ES7951 series, dramatically improving write endurance and extending capacity up to 8MB. This generation introduced the distinction between RAM cards (volatile, for data logging) and Flash cards (non-volatile, for program storage), a separation that remains architecturally significant for system integrators today. Compatibility between CPU generations within S7-300 is not universal: older CPUs (e.g., CPU 312, CPU 314) accept only lower-capacity cards, while later CPUs (e.g., CPU 317, CPU 319) support the full capacity range.

The third generation (2009–present) saw the introduction of the SIMATIC Micro Memory Card (MMC) format, which replaced the earlier card form factor across new CPU variants. However, legacy installations continue to operate on second-generation Flash cards, creating sustained demand for 6ES7951-series components in the MRO (Maintenance, Repair & Operations) market. Siemens officially announced the S7-300 platform as reaching end-of-sale in 2023, with end-of-support projected for 2028, making third-party lifecycle support providers essential for continued plant operation.

S7-300 Memory Card Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly deployed components within the Siemens SIMATIC S7-300 memory card product family. Each entry reflects a distinct capacity, card type, or compatibility profile.

Flash Memory Cards (Non-Volatile Program Storage)

6ES7951-0KE00-0AA0: 32KB Flash Memory Card; non-volatile program storage for S7-300 CPUs; no battery required.
6ES7951-0KF00-0AA0: 64KB Flash Memory Card; extended program capacity for mid-range S7-300 CPUs.
6ES7951-0KG00-0AA0: 128KB Flash Memory Card; suitable for CPU 315/316 with larger user program requirements.
6ES7951-0KH00-0AA0: 256KB Flash Memory Card; high-capacity non-volatile storage for complex ladder/FBD programs.
6ES7951-0KJ00-0AA0: 512KB Flash Memory Card; supports large structured control programs on CPU 317/318.
6ES7951-0KK00-0AA0: 1MB Flash Memory Card; maximum capacity for standard S7-300 Flash card format.
6ES7951-0KL00-0AA0: 2MB Flash Memory Card; extended capacity variant for data-intensive applications.
6ES7951-0KM00-0AA0: 4MB Flash Memory Card; used in high-density I/O configurations with large DB blocks.
6ES7951-0KN00-0AA0: 8MB Flash Memory Card; maximum capacity Flash card in the 6ES7951 series.

RAM Memory Cards (Volatile Data Storage)

6ES7951-1KA00-0AA0: 32KB RAM Card; volatile data logging and recipe storage; requires CPU battery backup.
6ES7951-1KB00-0AA0: 64KB RAM Card; extended volatile storage for process data acquisition applications.
6ES7951-1KC00-0AA0: 128KB RAM Card; used in batch process environments requiring large data block retention.
6ES7951-1KD00-0AA0: 256KB RAM Card; high-capacity volatile storage for historian-integrated S7-300 systems.
6ES7951-1KE00-0AA0: 512KB RAM Card; maximum standard RAM card capacity for S7-300 platform.

Micro Memory Cards (MMC — Later S7-300 CPU Variants)

6ES7953-8LF20-0AA0: 64KB Micro Memory Card (MMC); compatible with CPU 312C, 313C, 314C-2 and later variants.
6ES7953-8LG11-0AA0: 128KB MMC; standard replacement card for CPU 315-2 DP and CPU 316-2 DP.
6ES7953-8LJ20-0AA0: 512KB MMC; supports CPU 317-2 DP/PN with large program and data block requirements.
6ES7953-8LL20-0AA0: 2MB MMC; used in CPU 319-3 PN/DP for maximum program complexity deployments.
6ES7953-8LM20-0AA0: 4MB MMC; highest-capacity Micro Memory Card in the S7-300 MMC range.

Quality Control for the S7-300 Memory Card Range

Memory cards for PLC applications present a specific failure mode profile distinct from general-purpose Flash storage: write-cycle exhaustion, contact oxidation on the card edge connector, and firmware version mismatches between card and CPU are the three primary causes of field failures. DriveKNMS applies a structured test protocol to all S7-300 memory cards prior to shipment.