SIEMENS 6ES7953-8LJ31-0AA0 Micro Memory Card 512KB | Replacement, Equivalent & Selection Guide
The SIEMENS 6ES7953-8LJ31-0AA0 is a 512 KB Micro Memory Card (MMC) designed for use with SIMATIC S7-300, C7, and ET 200 distributed I/O systems. It serves as the non-volatile program and data storage medium for S7-300 CPUs — no battery backup required. Whether you are sourcing an original unit, evaluating compatible replacements, or selecting the right memory size for your application, this guide provides the technical detail and selection criteria you need.
Technical Specifications
- Part Number: 6ES7953-8LJ31-0AA0
- Manufacturer: Siemens AG
- Product Family: SIMATIC S7-300 Micro Memory Card
- Memory Capacity: 512 KB
- Memory Type: Flash EEPROM (non-volatile, battery-free)
- Form Factor: MMC (Micro Memory Card), proprietary Siemens format
- Compatible CPU Slots: S7-300 CPU MMC slot
- Operating Temperature: 0 °C to +60 °C
- Storage Temperature: −40 °C to +85 °C
- Write Cycles: ≥ 100,000 (typical)
- Data Retention: ≥ 10 years without power
- Weight: approx. 30 g
- Firmware Version: V3.1 (0AA0 suffix)
- RoHS Compliant: Yes
Compatible Replacement & Equivalent Models
The table below lists direct replacements and functionally equivalent Siemens MMC variants. Always verify CPU compatibility before substituting.
| Part Number | Capacity | Notes |
|---|---|---|
| 6ES7953-8LJ31-0AA0 | 512 KB | This product — original Siemens MMC |
| 6ES7953-8LJ30-0AA0 | 512 KB | Previous hardware revision (V3.0); functionally equivalent for most CPUs |
| 6ES7953-8LG11-0AA0 | 256 KB | Smaller capacity; suitable only if program size allows |
| 6ES7953-8LL31-0AA0 | 2 MB | Larger capacity; drop-in compatible, recommended for data-logging applications |
| 6ES7953-8LM32-0AA0 | 4 MB | Maximum standard MMC size; use for large programs or extensive data archiving |
Note: Third-party MMC clones are not officially supported by Siemens and may cause CPU boot errors or data corruption. Konmask.com supplies only genuine Siemens-branded MMC cards.
Why Choose the Original Model
- Guaranteed compatibility: Validated by Siemens for all S7-300 CPU variants that accept a 512 KB MMC.
- Firmware integrity: The 0AA0 hardware revision ensures compatibility with current STEP 7 and TIA Portal programming tools.
- Long-term data retention: Flash EEPROM technology retains program data for 10+ years without battery — critical for infrequently powered machinery.
- Proven write endurance: ≥ 100,000 write cycles supports frequent program updates and data logging without card degradation.
- Regulatory traceability: Genuine Siemens parts carry full CE/UL documentation for audit and compliance purposes.
Typical Applications
- Program storage for SIMATIC S7-300 CPUs (e.g., CPU 314, CPU 315-2 DP, CPU 317-2 PN/DP)
- Firmware and configuration backup for C7 all-in-one controllers
- Recipe and parameter storage in food & beverage processing lines
- Data logging in water treatment and utilities SCADA systems
- Spare/replacement card for maintenance inventory in automotive and discrete manufacturing
- Program transfer between CPUs during commissioning or field replacement
System Compatibility
- Compatible Systems: SIMATIC S7-300 (all CPU models with MMC slot), C7-626, C7-633, C7-634, ET 200 CPUs
- Programming Software: SIMATIC STEP 7 V5.x, TIA Portal V13 and above (via legacy S7-300 project)
- Card Reader: Siemens SIMATIC Micro Memory Card Reader/Writer (6ES7792-0AA00-0XA0) for offline programming
- Not Compatible With: S7-400 (uses a different memory card format), S7-1200/S7-1500 (use SD-based SIMATIC Memory Cards)
Selection Guide
Use the following criteria to select the correct MMC capacity for your application:
- Program size only (< 256 KB): 6ES7953-8LG11-0AA0 (256 KB) is sufficient and more cost-effective.
- Standard program + moderate data (< 512 KB): 6ES7953-8LJ31-0AA0 (512 KB) — this product — is the most common choice and covers the majority of S7-300 applications.
- Large programs or data logging (< 2 MB): Select 6ES7953-8LL31-0AA0 (2 MB) for applications with extensive recipe tables, alarm logs, or large FB/DB structures.
- Maximum capacity required: 6ES7953-8LM32-0AA0 (4 MB) for the most demanding data archiving or multi-program storage scenarios.
- Unsure of program size? Check the CPU’s online memory overview in STEP 7 (PLC > Module Information > Memory) or contact our team for a free pre-sales consultation.
Quality Assurance & Sourcing
- Source: Konmask.com procures directly from authorized Siemens distributors and certified industrial surplus channels.
- Inspection: Every unit undergoes visual inspection and label verification prior to dispatch.
- Packaging: Ships in original Siemens anti-static packaging or equivalent ESD-safe packaging.
- Warranty: 12-month warranty against manufacturing defects.
- Traceability: Batch and serial documentation available upon request for regulated industries.
How to Order
- Online: Add to cart directly from this page. Stock availability is shown in real time.
- Bulk / Project Inquiry: Email support@konmask.com with your BOM or project requirements for a volume quotation.
- Lead Time: In-stock orders ship within 1–2 business days. Out-of-stock items: contact us for ETA.
- Export & Cross-border: We support international shipping with full commercial invoice and HS code documentation (HS: 8473.30).
- Phone / WhatsApp: +0086 19859288691
Replacement & Compatibility FAQ
Q: Can I use a 2 MB MMC (6ES7953-8LL31-0AA0) in place of the 512 KB card?
A: Yes. Larger-capacity MMCs are backward compatible with all S7-300 CPUs that accept the 512 KB card. The CPU will simply use the capacity it needs.
Q: Will my program be lost if I remove the MMC while the CPU is powered?
A: Siemens recommends switching the CPU to STOP mode before removing the MMC. Hot-swapping is not supported and may cause data corruption.
Q: Is the 6ES7953-8LJ30-0AA0 (V3.0) a safe replacement for the 8LJ31-0AA0 (V3.1)?
A: For most applications, yes. The V3.1 revision introduced minor improvements in write endurance. If your CPU firmware is current, either revision will function correctly.
Q: Can this MMC be used with an S7-1200 or S7-1500 PLC?
A: No. S7-1200 and S7-1500 use a different SIMATIC Memory Card (SD-based, e.g., 6ES7954-8LF03-0AA0). The MMC format is exclusive to S7-300/C7/ET200 systems.
Q: How do I transfer a program from one CPU to another using the MMC?
A: In STEP 7, use PLC > Download to Memory Card to write the program to the MMC offline via a card reader, then insert the MMC into the target CPU and power on. The CPU will load the program automatically.
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