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The 6ES5928-3UB21 functions as the central processor for the S5-115U system. This processor module executes user logic and controls all connected I/O. It replaces the older CPU921 and CPU922 variants effectively. Consequently, you gain faster cycle times and expanded memory capacity.
You can program this module using the STEP 5 software environment. The 6ES5928-3UB21 supports all five standard programming languages. These include STL, LAD, CSF, SCL, and GRAPH 5. Therefore, engineers can choose their preferred method for each application.
Memory Architecture and Data Storage
This module includes both RAM and EPROM storage options. The 6ES5928-3UB21 provides 32 KB of internal user memory. A separate 16 KB holds system data and operating system code. You can expand the total memory using external submodules as needed.
The processor stores retentive data in a small capacitor-backed area. This energy storage maintains critical values for up to 48 hours. The 6ES5928-3UB21 does not rely on replaceable batteries for this purpose. Below is a complete breakdown of its technical characteristics.
| Specification | Detail |
|---|---|
| Processor Type | CPU928 (16-bit architecture) |
| User Memory | 32 KB RAM (expandable via submodule) |
| System Memory | 16 KB ROM (Operating System) |
| Energy Storage | Capacitor-backed (48 hours retention) |
| Programming Languages | STL, LAD, CSF, SCL, GRAPH 5 |
| Dimensions (H x W x D) | 250 mm x 25 mm x 190 mm |
| Weight | 0.22 kg (Approx.) |
| Operating Voltage | 24V DC (via backplane) |
Interface Layout and Connectivity Options
A single 48-pin front connector links the CPU to the I/O bus. The 6ES5928-3UB21 features one serial programming port on the front panel. This 15-pin D-sub connector uses the standard 3964R protocol. An 8-position DIP switch allows configuration of various system parameters.
Two status LEDs provide immediate diagnostic information. The green RUN light indicates normal processor operation. The red STOP light signals a hardware fault or program error. The 6ES5928-3UB21 also includes a battery-backed real-time clock option.
Operational Benefits for Control Applications
This processor module handles complex interlocking and sequencing tasks easily. The 6ES5928-3UB21 executes 1K of statement list logic in under 1.5 milliseconds. It supports up to 1024 digital I/O points and 128 analog channels. Engineers trust this module for legacy system upgrades and replacements.