Siemens 6ES7953-8LF20-0AA0 – 4MB Micro Memory Card | SIMATIC S7-300 Platform
Engineering Background
The SIMATIC S7-300 series has been the backbone of industrial automation worldwide for over two decades, deployed across automotive assembly lines, chemical processing plants, water treatment facilities, and discrete manufacturing cells. Reliable non-volatile program storage is mission-critical in these environments — a power interruption must never result in program loss or unplanned downtime.
Product Positioning
The Siemens 6ES7953-8LF20-0AA0 is a 4MB Flash-based Micro Memory Card (MMC) designed exclusively for SIMATIC S7-300 CPUs. It serves as the primary non-volatile storage medium, retaining the user program, data blocks, and configuration data without battery backup. This card is the standard choice for mid-complexity S7-300 applications requiring robust, maintenance-free program retention.
Complete Technical Specifications
| Parameter | Value |
|---|---|
| Order Number (MLFB) | 6ES7953-8LF20-0AA0 |
| Product Family | SIMATIC S7-300 Micro Memory Card |
| Storage Capacity | 4 MB (Flash) |
| Memory Type | Non-volatile Flash (no battery required) |
| Form Factor | Micro Memory Card (MMC), proprietary Siemens format |
| Compatible CPUs | All SIMATIC S7-300 CPUs with MMC slot (CPU 312, 313, 314, 315, 316, 317, 318, 319 series) |
| Stored Data | User program (OB/FB/FC/DB), system data, configuration |
| Data Retention | 10 years (without power) |
| Write Cycles | ≥ 100,000 (per Siemens specification) |
| Operating Temperature | 0 °C to +60 °C |
| Storage Temperature | -20 °C to +70 °C |
| Humidity | 5% to 95% RH (non-condensing) |
| Protection Class | IP20 (when inserted in CPU) |
| Programming Interface | STEP 7 V5.x / TIA Portal (via CPU) |
| Dimensions (W×H×D) | Approx. 11 × 15 × 1 mm |
| Weight | Approx. 2 g |
| Certifications | CE, UL, cULus, ATEX (zone 2), FM (Class I, Div. 2) |
| RoHS Compliance | Yes |
Proven Application Environments
- Automotive Manufacturing: Body-in-white welding lines, paint shop conveyors, powertrain assembly — where program integrity across shift changes and power cycles is non-negotiable.
- Chemical & Pharmaceutical: Batch process controllers requiring validated, tamper-evident program storage with long data retention.
- Water & Wastewater Treatment: Remote pump stations and SCADA-integrated PLCs operating in high-humidity environments with infrequent maintenance windows.
- Food & Beverage: Packaging lines and filling machines requiring rapid CPU replacement with instant program restore via MMC swap.
- Energy & Utilities: Substation automation and turbine control panels demanding battery-free, maintenance-free memory solutions.
- Machine Tool & OEM: CNC auxiliary controllers and special-purpose machines shipped with pre-loaded programs on MMC for plug-and-play commissioning.
Engineering Advantages
- Battery-Free Retention: Flash memory eliminates the maintenance burden and failure risk of backup batteries — program is retained for 10+ years without power.
- Instant Program Restore: Replace a failed CPU, insert the MMC, power on — the S7-300 automatically loads the program. Zero STEP 7 intervention required on-site.
- Firmware & OS Updates: The MMC can also carry CPU firmware updates, enabling field upgrades without a programming device.
- Secure Program Transfer: Programs can be know-how protected and copied to replacement CPUs via MMC without exposing source code.
- 4MB Capacity: Sufficient for the vast majority of S7-300 applications including large DB arrays, recipe management, and multi-language message texts.
- Plug-and-Play: Hot-swap capable (with CPU in STOP mode); no special tools or adapters required.
System Architecture & Signal Flow
In the SIMATIC S7-300 architecture, the Micro Memory Card occupies the dedicated MMC slot on the CPU front panel. At power-up, the CPU copies the load memory contents (stored on the MMC) into internal work memory (RAM) for execution. All program downloads from STEP 7 / TIA Portal are written directly to the MMC via the CPU’s internal programming interface — no external card reader is required. Data blocks marked as non-retentive are re-initialized from the MMC image on each restart, while retentive DBs and memory areas are preserved across power cycles.
Signal Flow Summary: STEP 7 / TIA Portal → CPU MPI/PROFIBUS/Ethernet → CPU Internal Bus → MMC (Load Memory) → CPU Work Memory (RAM) → I/O Modules
Sourcing & Quality Verification
- Origin: Sourced from authorized Siemens distribution channels and verified industrial surplus with full traceability.
- Inspection: Each unit undergoes visual inspection for label integrity, connector condition, and physical authenticity markers.
- Functional Test: Cards are verified for read/write functionality prior to shipment using Siemens-compatible test equipment.
- Packaging: Anti-static pouch + protective case; original Siemens packaging preserved where available.
- Warranty: 12-month warranty against manufacturing defects. DOA replacement within 7 days of receipt.
Procurement Process
- Confirm Compatibility: Verify your S7-300 CPU model accepts the MMC format (all CPUs from CPU 312 onward do). CPU 31xC compact CPUs also use this card.
- Place Order: Add to cart and complete checkout. Bulk pricing available for orders of 5+ units — contact us for a quote.
- Lead Time: In-stock units ship within 1–2 business days. Express DHL/FedEx international shipping available.
- Documentation: Commercial invoice, packing list, and certificate of conformity provided with every shipment.
- After-Sales: Technical support available via email or WhatsApp for integration questions.
Technical FAQ
Q: Can I use this MMC with an S7-400 or S7-1200/1500 CPU?
A: No. The 6ES7953-8LF20-0AA0 is exclusively for SIMATIC S7-300 CPUs. S7-400 uses a different memory card format; S7-1200/1500 use standard SD cards.
Q: Do I need a card reader/programmer to write to this MMC?
A: No. Programming is done through the CPU via STEP 7 or TIA Portal. The CPU writes directly to the MMC during program download.
Q: What happens if the MMC is removed while the CPU is in RUN mode?
A: The CPU will transition to STOP mode and generate a diagnostic error. Always set the CPU to STOP before inserting or removing the MMC.
Q: Can I copy a program from one MMC to another?
A: Yes, using the STEP 7 “Memory Card” function or by downloading the program to a new MMC via the CPU. Know-how protection can restrict copying.
Q: Is 4MB sufficient for my application?
A: 4MB covers the majority of S7-300 programs. For very large applications with extensive DB data or message libraries, consider the 8MB (8LG) or 64MB (8LL) variants.
Q: What is the difference between 6ES7953-8LF20-0AA0 and 6ES7953-8LF31-0AA0?
A: Both are 4MB MMCs. The -8LF31- is a newer hardware revision with identical functionality and full backward compatibility.
© 2026 Konmask.com. All rights reserved.
Original Source: https://Konmask.com
Contact: support@konmask.com | +0086 19859288691
