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The Siemens 6ES5947-3UA11 functions as the main processor for the S5-115U PLC. This central processing unit executes your ladder logic and controls all I/O operations. It occupies the leftmost slot in a standard SIMATIC S5 rack.
Technical specifications of Siemens 6ES5947-3UA11
| Parameter | Specification |
|---|---|
| Brand | Siemens |
| Model | Siemens 6ES5947-3UA11 |
| Product Family | SIMATIC S5 |
| Sub-Family | S5-115U |
| Category | Central Processing Unit (CPU) |
| Memory Type | RAM with battery backup |
| User Program Memory | 8 KB |
| Processing Speed | 2 ms per 1K binary operations |
| Power Supply | 24V DC external |
| Current Consumption | 250 mA typical |
| Integrated Interfaces | 1 x RS-485 (15-pin D-sub), 1 x programming port |
| Number of Components | 1 main PCB, 1 battery holder, 4 status LEDs |
| Energy Storage | 1 x lithium battery (for RAM retention) |
| Battery Type | 3.6V lithium (Siemens 6ES5980-0AA11) |
| Battery Life | Approximately 1 year |
| Dimensions (L x W x H) | Approx. 25 cm x 12 cm x 5 cm |
| Weight | Approx. 0.45 kg |
| Operating Temperature | 0°C to 60°C |
Detailed Technical Analysis
The Siemens 6ES5947-3UA11 processes 1K binary operations in just 2 milliseconds. This execution speed suits most medium-scale automation applications perfectly. The unit stores your control program in battery-backed RAM. Therefore, a functioning lithium battery preserves your code during power outages.
Now let us examine its physical construction. The Siemens 6ES5947-3UA11 contains one main circuit board inside a sturdy metal housing. It features four front-panel status LEDs. These indicators show RUN, STOP, BATTERY, and SYSTEM ERROR conditions. The CPU weighs approximately 0.45 kilograms.
The processor includes two built-in communication interfaces. One RS-485 port connects to remote I/O racks or other CPUs. The second port serves exclusively as a programming interface. You can connect a Siemens programmer or an operator panel to this port. The Siemens 6ES5947-3UA11 draws 250 milliamps from the 24V DC supply.
Energy Storage and Battery Management
The Siemens 6ES5947-3UA11 relies on a single 3.6V lithium battery. This battery preserves your program and system parameters when power fails. A typical battery lasts about one year in normal operation. Replace the battery annually to prevent unexpected program loss.
The CPU warns you when the battery voltage drops too low. The BATTERY LED will either flash or remain steady. You can change the battery while the PLC stays powered on. This procedure prevents any loss of your valuable user program.
Installation and Compatibility
You mount the Siemens 6ES5947-3UA11 into the leftmost slot of an S5-115U rack. The CPU requires a 24V DC external power supply. Connect this supply to the dedicated power terminals on the module. The unit communicates with I/O modules through the backplane bus automatically.
Summary
To conclude, the Siemens 6ES5947-3UA11 delivers 8KB of battery-backed program memory. It weighs 0.45 kilograms and includes two integrated communication ports. Choose this CPU to keep your S5-115U system running reliably.