PLCs, Power Supplies & Others

Core Specifications of the SIMATIC S5 CPU Module

The 6ES5928-3UA21 belongs to the Siemens SIMATIC S5 family of CPU modules. This processor card handles control logic, arithmetic operations, and data exchange in industrial automation racks. Moreover, it suits legacy S5-115U and S5-135U systems that remain in active service.

Each module occupies a single slot in the central rack. Additionally, the unit weighs roughly 0.55 kg with its front connector installed. The front panel measures 20 mm in width and 130 mm in height, while the 3UA21 suffix defines the memory and interface configuration.

Interface and Mounting Details

The 6ES5928-3UA21 slides into the S5 central rack and locks with the backplane bus. Consequently, technicians complete replacement without rewiring field terminations. This module communicates through the S5 parallel bus at high speed. Therefore, it coordinates multiple I/O cards within the same system.

A front serial port supports programming and diagnostic access. Meanwhile, the battery-backed RAM retains program data during power interruptions.

Performance and Application Notes

Plant operators keep the 6ES5928-3UA21 in service for continuous process control. Furthermore, the module executes scan cycles with predictable timing behavior. Its CMOS RAM stores the user program and internal flags reliably. Meanwhile, the battery backup protects critical data during outages.

The module stores energy only in its backup battery, since the CPU itself draws backplane power. As a result, maintenance teams replace the battery on a scheduled basis.

Details