Siemens SIMATIC S7-300 Memory Cards

Technical Dossier

Product Details And Specifications

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

The Siemens SIMATIC S7-300 Memory Card series is a standardized non-volatile storage solution designed exclusively for use with SIMATIC S7-300 programmable logic controllers. These cards store user programs, data blocks, and firmware images in a format that survives power loss without battery backup. Deployed across global heavy industry — including petrochemical complexes, nuclear auxiliary systems, offshore platforms, and continuous-process refineries — the S7-300 CPU relies on these cards as the primary program carrier. Installed base estimates place the S7-300 platform at tens of millions of I/O points worldwide, making the Memory Card one of the highest-demand spare components in industrial MRO procurement.

The Evolution of S7-300 Memory Card Architecture

The S7-300 Memory Card architecture has passed through three distinct generations since the platform's commercial introduction in the mid-1990s. The first generation used Flash EPROM cards in a proprietary form factor, requiring a dedicated programming device (PG/PC with MPI adapter) for write operations. Capacity was limited to 64 KB and 256 KB variants, sufficient for the ladder-logic programs typical of that era.

The second generation, introduced alongside the S7-300 CPU 31xC family in the early 2000s, expanded capacity to 2 MB and 4 MB and introduced the ability to store S7 programs, data, and recipe files simultaneously. The physical connector remained backward-compatible with first-generation CPUs, preserving installed-base investment.

The third and current generation extended capacity to 8 MB (6ES7951-0KG00-0AA0) and introduced improved write-cycle endurance ratings. These cards are compatible with all S7-300 CPUs from CPU 312 through CPU 319-3 PN/DP. As Siemens has formally announced the S7-300 platform end-of-sale, the Memory Card series has entered its lifecycle maintenance phase. No new hardware revisions are planned; long-term support is provided through authorized spare-parts channels and third-party MRO suppliers such as DriveKNMS.

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

The following SKUs represent the verified, commercially available and historically shipped models within the SIMATIC S7-300 Memory Card family. Each entry reflects the card's storage capacity and primary application context.

6ES7951-0KA00-0AA0: 64 KB Flash card; program storage for compact S7-300 CPUs.
6ES7951-0KB00-0AA0: 128 KB Flash card; extended program and DB storage.
6ES7951-0KC00-0AA0: 256 KB Flash card; standard capacity for CPU 313/314 applications.
6ES7951-0KD00-0AA0: 512 KB Flash card; mid-range capacity for CPU 315 series.
6ES7951-0KE00-0AA0: 1 MB Flash card; supports large user programs with multiple DBs.
6ES7951-0KF00-0AA0: 2 MB Flash card; recipe and data-intensive process applications.
6ES7951-0KG00-0AA0: 8 MB Flash card; maximum capacity for CPU 317/319 with large data archives.
6ES7951-0KH00-0AA0: 4 MB Flash card; high-capacity variant for CPU 315-2 DP/PN.
6ES7951-1KA00-0AA0: 64 KB RAM card; volatile working memory expansion (legacy).
6ES7951-1KB00-0AA0: 128 KB RAM card; volatile DB expansion for early CPU 314.
6ES7951-1KC00-0AA0: 256 KB RAM card; legacy working memory for CPU 315 (battery required).
6ES7951-1KD00-0AA0: 512 KB RAM card; maximum volatile expansion for S7-300 (discontinued).
6ES7951-0LE00-0AA0: 1 MB Flash card, alternate hardware revision; CPU 315-2 PN/DP compatible.
6ES7951-0LF00-0AA0: 2 MB Flash card, alternate hardware revision; CPU 317-2 PN/DP compatible.
6ES7951-0LG00-0AA0: 8 MB Flash card, alternate hardware revision; CPU 319-3 PN/DP compatible.

Sourcing Hard-to-Find & Obsolete S7-300 Memory Card Parts

Siemens formally placed the S7-300 platform on end-of-sale status, with standard repair and spare-parts support continuing under Siemens Industry Online Support terms. However, procurement lead times through OEM channels for low-volume Memory Card orders — particularly the 64 KB, 128 KB, and RAM-type variants — have extended significantly. Many end-users operating legacy S7-300 installations in chemical plants, water treatment facilities, and power generation auxiliaries require these cards for emergency replacements without the option of a full CPU upgrade.

DriveKNMS maintains a dedicated inventory buffer for S7-300 Memory Cards across all capacity variants, including discontinued RAM-type cards. All stock is sourced from verified industrial surplus channels and subjected to functional verification before dispatch. For plant operators requiring long-term maintenance agreements covering S7-300 spare parts, DriveKNMS provides multi-year supply contracts with guaranteed stock reservation.

Quality Control for the S7-300 Memory Card Range

S7-300 Memory Cards present specific verification challenges due to their proprietary interface and the absence of standard JEDEC test protocols applicable to this form factor. DriveKNMS applies the following test sequence to all Memory Card units prior to shipment:

Each card is inserted into a verified S7-300 CPU test bench (CPU 315-2 DP reference unit) and subjected to a full program write-verify cycle using STEP 7 v5.6. The card is then power-cycled ten times to confirm non-volatile retention. Write-cycle count registers are read where accessible to screen for high-use units. Physical connector pins are inspected under magnification for oxidation or mechanical deformation. Cards that fail any stage of this sequence are quarantined and not returned to saleable stock.