Siemens 6ES5928-3UA12 SIMATIC S5 Central Processing Unit

The Siemens 6ES5928-3UA12, also cataloged as the 6ES5928-3UA12 CPU Processor Module, operates as a dedicated hardware component for central sequence execution and logical task evaluation within SIMATIC S5-135U/155U automation platforms. The hardware acts as an intelligent processing unit that runs STEP 5 machine instructions, updates bit-addressable images, and manages hardware interrupts across the parallel backplane bus structure.

Hardware Specifications

Siemens Local Backplane Execution

• Backplane Bus Communication Velocity Integration: The CPU 928 processor interfaces directly with the robust parallel S5 backplane bus assembly. It reads and writes memory blocks at the native bus communication velocity, processing inter-processor flags and coordinating peripheral digital or analog I/O addressing slots without introducing software instruction delay.
• I/O Density Scaling Control Matrix: The memory-mapped processing structure permits extensive I/O density scaling across extended multi-tier subracks. The internal memory allocation divides memory pages to allow concurrent access to input/output bit vectors while maintaining real-time task priorities during high-density cyclic processing operations.

Frequently Asked Questions

Q: How is the application program retained inside the volatile memory during a major panel power drop?

A: The 46 Kbyte integrated RAM is volatile and requires continuous power. To secure the logic parameters during a supply drop, the subrack backplane must be equipped with a functional backup battery, or the program must be burned into a non-volatile 64 Kbyte EPROM cartridge inserted into the faceplate socket.

Q: Can the 6ES5928-3UA12 processor module be unseated or hot-swapped while the subrack is energized?

A: No. The SIMATIC S5 backplane does not support active module extraction under live power. Pulling this CPU module while the 5 V DC or 24 V DC rails are live can induce electrical transients that disrupt the parallel data lines, cause fatal memory loss, or permanently damage the internal logic arrays.

Field Installation Guidelines

• Chassis Layout Alignment, Clearance Constraints, and Mechanical Seating: Insert the top and bottom tracking guides of the 0.86 lbs module into the designated slot lines of the S5-135U/155U subrack frame. Slide the card backward firmly until the rear connector blocks seat fully into the motherboard socket, then actuate the front locking lever to secure the hardware against industrial vibrations.
• Conductor Separation, Wireway Constraints, and Shield Grounding: Route any low-voltage programming adapter connections or communication interface cables inside separate wireways isolated from three-phase AC power lines or high-potential inductive lines. Ensure the chassis grounding springs on the card edges make direct contact with the subrack frame to route ambient electromagnetic transients away from the memory bus.