The Siemens SIMATIC S5 CPU 947R (part number 6ES5 947-3UR21) is a central processing unit designed for the S5-155H PLC system, offering redundancy capabilities for high-availability applications. Below is a detailed overview:

Device Description

The CPU 947R serves as the central controller within the S5-155H PLC system, managing and executing user programs, processing inputs and outputs, and facilitating communication with other system components. Its redundancy feature ensures continuous operation by switching to a backup CPU in case of a failure.

Technical Specifications

    Model Number: 6ES5 947-3UR21
    Memory: Specific RAM size not specified in the available sources
    Compatibility: Designed for use with the S5-155H PLC system
    Redundancy: Supports redundant configurations for high-availability applications
    Dimensions: Approximately 8.0" x 2.0" x 11.0" (20.3 cm x 5.1 cm x 27.9 cm)
    Weight: Approximately 0.5 kg

Programming

Programming the CPU 947R is accomplished using Siemens' STEP 5 software, which allows for the development, testing, and debugging of user programs tailored to specific automation tasks.

Data Program Information

The CPU 947R manages data blocks and user programs within its memory, providing sufficient space for complex automation processes.

Special Commands

The CPU 947R supports a comprehensive set of instructions, including logic operations, arithmetic functions, and data handling commands, enabling the execution of intricate control strategies.

Repair and Commissioning Recommendations

    Maintenance:
        Regularly inspect the CPU for signs of wear or damage.
        Ensure that firmware updates are applied as recommended by Siemens.

    Commissioning:
        Verify all connections and configurations before initiating the system.
        Conduct thorough testing of user programs in a controlled environment prior to full deployment.

Editor's Recommendations and Experiences

    Practical Tips:
        When implementing redundancy, ensure that both CPUs are synchronized and configured correctly to prevent system conflicts.

    Reliability Advice:
        Maintain a clean operating environment to prevent dust accumulation, which can affect performance.

    Thermal Management:
        Ensure adequate ventilation around the CPU to prevent overheating, which can lead to system failures.

+ Siemens S5 PLC User Manual (pdf page)

+ Siemens 6ES5 947-3UR21 User Manual (pdf)

+ Siemens Automation Homepage >

+ Siemens Automation Contact (for Automation Mall)