Application Scenarios
A petrochemical plant in the Middle East had been operating a SIMATIC S5-155U controller for its catalytic reformer unit since 1992. During a routine shutdown, the original 6ES5340-3KB42 memory submodule exhibited signs of data corruption—the CPU’s “memory fault” LED intermittently illuminated, and the engineering team could no longer reliably store modified process parameters. With no direct replacement available from Siemens, the plant faced a stark choice: invest $500,000+ in an S7 modernization or source a tested refurbished 6ES5340-3KB42.
By procuring a functionally tested unit from a specialized S5 spare parts provider, the maintenance team executed a seamless swap during a planned 8-hour maintenance window. The replacement 6ES5340-3KB42 was pre-loaded with a verified backup of the original program, and the reformer unit resumed operation with zero process interruptions. For plant managers overseeing legacy S5 assets, the 6ES5340-3KB42 is far more than a memory module—it is the key to avoiding a forced migration and preserving decades of proven control logic.
Parameter
| Main Parameter | Value / Description |
|---|---|
| Product Model | 6ES5340-3KB42 |
| Manufacturer | Siemens AG |
| Product Category | SIMATIC S5 340-Series Compact Memory Submodule (RAM) |
| Memory Type | Volatile RAM (requires CPU battery/PS backup for data retention) |
| Storage Capacity | 64 KB |
| Compatible Systems | SIMATIC S5-130U, S5-135U, S5-150U, S5-155U central controllers |
| Form Factor | Compact (Kompaktbauform) plug-in submodule |
| Interface | Edge connector, inserts directly into CPU memory slot |
| Power Supply | 5 V DC via CPU backplane (no separate power required) |
| Status | Officially discontinued by Siemens since January 10, 2005 (no direct replacement) |
| Operating Temperature | 0 °C to +60 °C |
| Storage Temperature | -40 °C to +70 °C |
| Net Weight | 0.5 kg |
| Dimensions (L × W × H) | 25.4 cm × 2.5 cm × 20.3 cm |
| Commodity Code | 85371098 / 85371099 |
| Country of Origin | Germany |
| Mounting | Direct insertion into dedicated memory slot on S5 CPU front panel |
| Typical Availability | Refurbished/tested units, global spare parts stock |
Technical Principles and Innovative Values
- Innovation Point 1: Compact Form Factor for Dense Cabinet Layouts. The 6ES5340-3KB42 delivers 64 KB of RAM in a slim, compact submodule that occupies minimal space on the S5 CPU front panel. This space-efficient design was revolutionary for its era, allowing engineers to maximize memory capacity without expanding the physical footprint of the control cabinet—a critical advantage in retrofit and brownfield applications.
- Innovation Point 2: Seamless S5 Backplane Integration. The 6ES5340-3KB42 interfaces directly with the S5 CPU through a dedicated edge-connector slot. No external wiring, no separate power supply, and no address configuration are required—the CPU automatically detects and maps the 64 KB memory space at power-up. This plug-and-play architecture dramatically simplifies both initial deployment and field replacement.
- Innovation Point 3: Battery-Backed Data Retention. When paired with a healthy CPU backup battery (or the rack power supply’s buffering circuit), the 6ES5340-3KB42 retains user programs and process data indefinitely during power outages. This volatile-RAM-plus-battery approach was the S5 design philosophy, balancing fast read/write access with reliable long-term storage—and the 6ES5340-3KB42 executes this role with decades-proven reliability.
- Innovation Point 4: Discontinued but Indispensable. Siemens cancelled the 6ES5340-3KB42 on January 10, 2005 without a replacement part, which has made it a highly sought-after commodity in the legacy automation aftermarket. Specialized providers now offer refurbished, functionally tested units with warranties of up
