SIEMENS 6ES7953-8LF31-0AA0 – 8MB Micro Memory Card | SIMATIC S7-300 / ET 200 Platform
The SIEMENS 6ES7953-8LF31-0AA0 is an 8MB Micro Memory Card (MMC) engineered exclusively for the SIMATIC S7-300 PLC and ET 200 distributed I/O platform. As the mandatory non-volatile program storage medium for S7-300 CPUs, this MMC retains the user program, data blocks, and configuration data without battery backup — eliminating a critical single point of failure in industrial control systems.
Procurement engineers and automation integrators rely on the 6ES7953-8LF31-0AA0 as a direct OEM replacement or capacity upgrade for existing S7-300 installations. Konmask.com maintains verified stock sourced through authorized industrial distribution channels, with full traceability documentation available on request.
Complete Technical Specifications
| Part Number | 6ES7953-8LF31-0AA0 |
| MLFB / Order No. | 6ES7953-8LF31-0AA0 |
| Product Family | SIMATIC S7-300 Micro Memory Card |
| Memory Type | Flash EEPROM (Non-volatile) |
| Storage Capacity | 8 MB |
| Form Factor | MMC (Micro Memory Card) – proprietary SIMATIC format |
| Compatible CPUs | All SIMATIC S7-300 CPUs (e.g. CPU 312, 313, 314, 315, 317, 319); ET 200 CPUs |
| Battery Backup Required | No – retains data without battery |
| Write Cycles | ≥ 100,000 (per SIEMENS specification) |
| Data Retention | 10 years (at 55 °C) |
| Operating Temperature | 0 °C to +60 °C |
| Storage Temperature | -20 °C to +85 °C |
| Humidity | 5% to 95% RH (non-condensing) |
| Protection Class | IP20 (when inserted in CPU slot) |
| Dimensions (W×H×D) | Approx. 24 × 32 × 2.1 mm |
| Weight | Approx. 2 g |
| Manufacturer | Siemens AG, Germany |
| HS Code | 8523.52 |
| RoHS Compliance | Yes |
Proven Application Environments
- Discrete Manufacturing: Automotive assembly lines, CNC machine tool controllers, robotic cell PLCs requiring large user program storage.
- Process Industry: Chemical plant DCS integration nodes, water treatment SCADA outstations, oil & gas wellhead RTUs using S7-300 CPUs.
- Building Automation & Infrastructure: HVAC control panels, power distribution substations, tunnel ventilation systems.
- Spare Parts & MRO: Direct OEM replacement for failed or corrupted MMCs; capacity upgrade from 2MB / 4MB variants (8LG31, 8LJ31) to 8MB.
- Commissioning & Cloning: Program transfer medium for rapid CPU replacement and multi-site replication of identical machine configurations.
Engineering Advantages
- Battery-Free Retention: Flash EEPROM architecture eliminates battery maintenance cycles and associated downtime risk — critical for remote or unmanned installations.
- 8MB Headroom: Accommodates large user programs, extensive DB structures, and S7-Graph / SCL source code storage within a single card — the largest standard MMC capacity in the S7-300 range.
- Plug-and-Play Replacement: Identical mechanical and electrical interface to all S7-300 MMC variants; no firmware update or CPU reconfiguration required.
- Certified Industrial Grade: Qualified to SIEMENS SIMATIC environmental and EMC standards; suitable for Class I, Division 2 / Zone 2 installations when mounted in compliant enclosures.
- Long Service Life: 10-year data retention at 55 °C and ≥100,000 write cycles ensure multi-decade operational reliability in continuous-process environments.
System Architecture & Signal Flow
In the SIMATIC S7-300 architecture, the MMC occupies the dedicated card slot on the CPU front panel and serves as the load memory. At power-up, the CPU copies executable code from the MMC into internal work memory (RAM). All program downloads from STEP 7 / TIA Portal are written directly to the MMC; the CPU’s internal RAM is volatile and is always restored from the MMC on restart.
- Load Memory (MMC): Stores OB/FB/FC/DB source and object code, hardware configuration, and system data.
- Work Memory (CPU RAM): Executes the program; populated from MMC at each CPU restart.
- Retentive Memory: Selected DB and M-bit ranges can be declared retentive; these are written back to MMC on power-down (requires CPU support).
- Programming Interface: STEP 7 v5.x (Classic) and TIA Portal V13+ with S7-300 support; MMC appears as a standard download target.
Sourcing & Quality Verification
All SIEMENS modules listed on Konmask.com are sourced through verified industrial distribution channels. Each unit undergoes the following verification process before dispatch:
- Visual inspection for label authenticity, hologram integrity, and housing condition.
- Functional read/write test using SIMATIC CPU or dedicated MMC programmer.
- Firmware version and capacity verification against SIEMENS MLFB specification.
- Anti-static packaging with humidity indicator card for international shipment.
Certificates of conformity and test reports are available upon request for MRO and OEM procurement teams.
Procurement Process
- Lead Time: In-stock items ship within 1–3 business days; ETA confirmation provided at order placement.
- MOQ: 1 piece (no minimum order quantity).
- Bulk Pricing: Volume discounts available for orders of 5+ units — contact support@konmask.com for a formal quotation.
- Export Documentation: Commercial invoice, packing list, and certificate of origin provided for all international shipments.
- Payment: T/T bank transfer, PayPal, and major credit cards accepted.
- Warranty: 12-month warranty against manufacturing defects; DOA replacement within 7 days of receipt.
Technical FAQ
- Q: Is the 6ES7953-8LF31-0AA0 compatible with S7-400 or S7-1200/1500 CPUs?
- No. This MMC uses the proprietary SIMATIC S7-300 card format and is not compatible with S7-400 (which uses a different flash card) or S7-1200/1500 (which use SIMATIC Memory Cards with a different interface).
- Q: Can I use a standard SD card or USB drive instead?
- No. S7-300 CPUs require the proprietary SIMATIC MMC format. Standard SD cards are not recognized by the CPU hardware or STEP 7 software.
- Q: What is the difference between 8LG31 (2MB), 8LJ31 (4MB), and 8LF31 (8MB)?
- The suffix encodes capacity: LG=2MB, LJ=4MB, LF=8MB. All are mechanically and electrically identical; choose based on your program size requirements. The 8LF31 (8MB) is recommended for new installations to maximize headroom.
- Q: Will the program be lost if I remove the MMC while the CPU is running?
- Removing the MMC while the CPU is in RUN mode will cause an immediate CPU STOP fault. Always switch the CPU to STOP mode before inserting or removing the MMC.
- Q: Do you provide STEP 7 project files or programming support?
- We supply hardware only. For STEP 7 / TIA Portal programming support, consult your local Siemens Technical Support or a certified SIMATIC automation integrator.
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