SIEMENS 6ES7953-8LG20-0AA0 Micro Memory Card 8MB | Replacement, Equivalent & Selection Guide
The SIEMENS 6ES7953-8LG20-0AA0 is an 8 MB Micro Memory Card (MMC) designed for SIMATIC S7-300 programmable logic controllers. It stores user programs, data blocks, and firmware updates, serving as the primary non-volatile storage medium for S7-300 CPUs. This page provides full technical specifications, compatible replacement models, application guidance, and sourcing information to help engineers and procurement teams make confident selection decisions.
Technical Specifications
| Parameter | Value |
|---|---|
| Part Number | 6ES7953-8LG20-0AA0 |
| Brand | SIEMENS |
| Series | SIMATIC S7-300 |
| Type | Micro Memory Card (MMC) |
| Storage Capacity | 8 MB |
| Interface | Proprietary MMC slot (S7-300 CPU) |
| Operating Voltage | 3.3 V |
| Operating Temperature | 0 °C to +60 °C |
| Storage Temperature | -20 °C to +85 °C |
| Data Retention | 10 years (without power) |
| Write Cycles | 100,000 (typical) |
| Weight | Approx. 2 g |
| Dimensions | 11 mm × 15 mm × 1.4 mm |
| RoHS Compliant | Yes |
| Country of Origin | Germany / EU |
Compatible Replacement & Equivalent Models
The table below lists SIEMENS MMC cards within the same 6ES7953 family, ordered by capacity, to assist with direct replacement or upgrade decisions.
| Part Number | Capacity | Compatibility | Notes |
|---|---|---|---|
| 6ES7953-8LG20-0AA0 | 8 MB | S7-300 CPUs | This product — standard choice |
| 6ES7953-8LF20-0AA0 | 4 MB | S7-300 CPUs | Lower capacity; suitable for smaller programs |
| 6ES7953-8LJ20-0AA0 | 16 MB | S7-300 CPUs | Upgrade option for larger data blocks |
| 6ES7953-8LL20-0AA0 | 64 MB | S7-300 CPUs | High-capacity; for complex projects |
| 6ES7953-8LP20-0AA0 | 256 MB | S7-300 CPUs | Maximum capacity in the MMC series |
Note: All 6ES7953-8Lx20-0AA0 cards share the same physical form factor and are pin-compatible with S7-300 CPU MMC slots. Capacity is the only differentiator.
Why Choose the Original Model
- Guaranteed compatibility: Factory-validated for all SIMATIC S7-300 CPUs with MMC slots.
- Firmware update support: Required for CPU firmware upgrades via STEP 7 or TIA Portal.
- Non-volatile retention: Retains program data for 10+ years without backup battery.
- Industrial-grade reliability: Designed for 24/7 operation in harsh industrial environments.
- SIEMENS quality assurance: Manufactured and tested to IEC 61131-2 standards.
Typical Applications
- Program and data block storage for SIMATIC S7-300 CPUs (e.g., CPU 314, CPU 315-2 DP, CPU 317-2 PN/DP)
- CPU firmware update carrier
- Machine tool and CNC controller backup
- Process automation in chemical, pharmaceutical, and food & beverage industries
- Building automation and HVAC control systems
- Water treatment and utilities SCADA integration
- Automotive assembly line PLC systems
System Compatibility
The 6ES7953-8LG20-0AA0 is compatible with the following SIMATIC S7-300 CPU families:
- CPU 312 / 312C
- CPU 313C / 313C-2 DP / 313C-2 PtP
- CPU 314 / 314C-2 DP / 314C-2 PtP / 314C-2 PN/DP
- CPU 315-2 DP / 315-2 PN/DP
- CPU 317-2 DP / 317-2 PN/DP
- CPU 319-3 PN/DP
- CPU 31xC series (compact CPUs)
Not compatible with S7-400, S7-1200, or S7-1500 series (different memory card formats).
Selection Guide
Use the following criteria to select the correct MMC capacity for your application:
- Program size < 2 MB: 6ES7953-8LF20-0AA0 (4 MB) is sufficient.
- Program size 2–6 MB / standard projects: 6ES7953-8LG20-0AA0 (8 MB) — recommended for most applications.
- Large data logging or recipe management: Consider 6ES7953-8LJ20-0AA0 (16 MB) or higher.
- Firmware update only: Any capacity ≥ 4 MB is acceptable.
- Redundant CPU systems (H-systems): Two identical MMC cards required; use the same part number for both.
Quality Assurance & Sourcing
- All units sourced from authorized SIEMENS distribution channels or verified surplus stock.
- Each card undergoes functional verification before shipment.
- Original SIEMENS packaging and labeling preserved where available.
- Traceability documentation available upon request (batch/lot records).
- Export compliance checked for applicable trade regulations (EAR/ECCN).
How to Order
- Confirm your S7-300 CPU model and current MMC slot status.
- Select the required capacity using the Selection Guide above.
- Add to cart or contact us for bulk/project pricing.
- Provide your project PO number for B2B invoicing.
- Standard lead time: 1–3 business days (stock items); 5–10 days (sourced items).
For urgent requirements or volume orders, contact: support@konmask.com | +0086 19859288691
Replacement & Compatibility FAQ
Q: Can I use a higher-capacity MMC (e.g., 16 MB) as a direct replacement for the 8 MB 6ES7953-8LG20-0AA0?
A: Yes. All 6ES7953-8Lx20-0AA0 cards are physically and electrically interchangeable. A higher-capacity card will work correctly; unused capacity is simply not utilized.
Q: Is the 6ES7953-8LG20-0AA0 compatible with S7-1200 or S7-1500 CPUs?
A: No. S7-1200 uses a standard SD card, and S7-1500 uses a SIMATIC Memory Card (6ES7954 series). The MMC format is exclusive to S7-300 and some S7-400 variants.
Q: Can I use a standard commercial MMC card as a replacement?
A: No. SIEMENS S7-300 CPUs require the proprietary SIMATIC MMC format. Standard commercial MMC cards are not recognized by the CPU.
Q: Does the card retain data after power loss?
A: Yes. The MMC is non-volatile flash memory and retains all stored data indefinitely without power or battery backup.
Q: How do I transfer a program from an old MMC to a new one?
A: Use STEP 7 (Simatic Manager) or TIA Portal to upload the program from the CPU/old card, then download it to the new card via the CPU’s MMC slot.
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