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This Siemens central processing unit serves as the core controller for S5 automation systems. The Siemens 6ES5905-3RA11 executes user programs with high efficiency and precision. Its powerful architecture handles complex logic and arithmetic operations effectively. This unit supports extensive system expansion with additional I/O modules.
Physical Dimensions and Mounting Specifications
The central processing unit measures 232 mm in height and 25 mm in width. Its overall depth reaches 160 mm including the front connector. This unit weighs approximately 0.65 kilograms for stable rack installation. The housing features a robust metal casing for electromagnetic shielding. The Siemens 6ES5905-3RA11 plugs directly into any S5 rack slot. A 48-pin backplane connector transfers power and signals to the system.
Processor and Memory Architecture
A 16-bit microprocessor with 10 MHz clock speed handles all computational tasks. This processor executes bit operations in 0.3 microseconds for rapid response. Word operations complete in 1.2 microseconds for efficient data handling. The unit includes 48 KB of RAM for user program and data storage. A separate 96 KB EPROM holds the operating system firmware. The Siemens 6ES5905-3RA11 provides 24 KB of retentive memory for critical data. An integrated lithium battery maintains this memory for up to 5 years. An internal capacitor of 680 µF bridges brief power interruptions.
Communication and System Capabilities
This CPU offers one RS-232 port for programming device connection. A second RS-485 interface supports remote I/O and inter-controller communication. The unit handles up to 1024 digital I/O points for system flexibility. It also manages up to 128 analog channels for process monitoring. The Siemens 6ES5905-3RA11 processes 1024 instructions in approximately 2.2 milliseconds. Six interrupt inputs enable priority-based event handling. A watchdog timer monitors program execution continuously.
Detailed Specification Table
| Parameter | Specification |
|---|---|
| Dimensions (H x W x D) | 232 mm x 25 mm x 160 mm |
| Weight | Approx. 0.65 kg |
| Processor Type | 16-bit microprocessor |
| Clock Frequency | 10 MHz |
| Bit Operation Time | 0.3 µs |
| Word Operation Time | 1.2 µs |
| RAM Capacity | 48 KB |
| EPROM Capacity | 96 KB |
| Retentive Memory | 24 KB |
| Battery Backup Life | 5 years |
| Energy Storage Capacitance | 680 µF |
| Digital I/O Capacity | 1024 points |
| Analog Channel Capacity | 128 channels |
| Program Execution Time | 2.2 ms / 1024 instructions |
| Communication Ports | RS-232, RS-485 |
| Interrupt Inputs | 6 |
Application and Commissioning Guidelines
Insert this CPU into the designated slot of the S5 rack system. Connect the programming device to the RS-232 port for initial setup. Download the user program and system parameters via the serial interface. The Siemens 6ES5905-3RA11 operates reliably between 0°C and 60°C. Ensure sufficient airflow around the CPU for proper heat dissipation. Configure the communication settings to match peripheral device requirements. Monitor the front-panel LEDs for system status and fault indicators. Replace the backup battery every four years to prevent memory loss.