Siemens SIMATIC S5-115U Modules: 6ES5947-3UA22

Technical Dossier

Product Details And Specifications

Siemens SIMATIC S5-115U Series Technical Notes

The Siemens SIMATIC S5-115U is a mid-range programmable logic controller platform that achieved widespread deployment across global heavy industry from the early 1980s through the 2000s. It remains installed in active production environments including petrochemical refineries, nuclear auxiliary systems, offshore platforms, and continuous-process chemical plants. Its modular backplane architecture, deterministic scan cycle, and robust industrial-grade hardware made it a standard reference design for process automation engineers during its production lifecycle. The 6ES5947-3UA22 is the central processing unit of this platform, executing the user program, managing I/O communication across the backplane bus, and coordinating all connected peripheral modules.

The Evolution of SIMATIC S5-115U Architecture

The S5-115U was introduced as part of Siemens' second-generation SIMATIC S5 family, succeeding the S5-110 and S5-130 platforms. Its architecture is built around the SINEC H1 and SINEC L2 communication buses, with a parallel backplane that supports up to 32 I/O modules per rack via the EU 183/185/186 expansion units. Early CPU variants such as the 6ES5941-7UA11 offered 16 KB program memory; successive revisions culminated in the 6ES5947-3UA22 with 48 KB RAM and integrated battery-backed data retention. The platform uses STEP 5 programming software (versions 6.x through 7.x), which remains the only compatible programming environment. Siemens officially declared the S5-115U end-of-life and discontinued new production in 2013, with extended spare parts support running through 2023. Installations still in service require third-party lifecycle support for CPU modules, I/O cards, and power supplies. The successor platform is the SIMATIC S7-400, with migration paths documented under Siemens Migration Service offerings.

SIMATIC S5-115U Full Catalog & Functionalities (SKU List)

CPU / Processor Modules

• 6ES5941-7UA11: CPU 941, 16 KB RAM, basic S5-115U processor unit
• 6ES5942-7UA11: CPU 942, 32 KB RAM, enhanced scan performance
• 6ES5943-7UA11: CPU 943, 48 KB RAM, extended I/O addressing
• 6ES5944-7UA11: CPU 944, 48 KB RAM, high-speed interrupt processing
• 6ES5945-7UA21: CPU 945, 96 KB RAM, multiprocessor-capable unit
• 6ES5947-3UA22: CPU 947, 48 KB RAM, battery-backed SRAM, integrated MPI interface, primary CPU for S5-115U systems
• 6ES5948-3UA21: CPU 948, 96 KB RAM, dual-port RAM for multiprocessor configurations

Digital Input / Output Modules

• 6ES5420-7LA11: DI 420, 32-channel 24 VDC digital input module
• 6ES5430-7LA11: DI 430, 32-channel 24 VDC digital input, isolated
• 6ES5440-7LA11: DO 440, 32-channel 24 VDC digital output, 0.5 A per channel
• 6ES5451-7LA11: DO 451, 32-channel relay output module, 230 VAC

Analog Input / Output Modules

• 6ES5460-4UA13: AI 460, 8-channel analog input, ±10 V / 4–20 mA
• 6ES5464-8MA11: AI 464, 16-channel analog input, thermocouple/RTD compatible
• 6ES5470-4UA12: AO 470, 4-channel analog output, 12-bit resolution

Communication & Interface Modules

• 6ES5521-8MA11: CP 521, serial communication processor, RS-232/RS-422
• 6ES5524-3UA15: CP 524, SINEC H1 Ethernet communication processor
• 6ES5525-3UA21: CP 525, PROFIBUS-DP master interface module

Power Supply Modules

• 6ES5955-3LC41: PS 955, 24 VDC / 10 A regulated power supply for S5-115U rack
• 6ES5955-3NC41: PS 955, 120/230 VAC input, 24 VDC / 15 A output

Quality Control for the SIMATIC S5-115U Range

Each S5-115U module processed by DriveKNMS undergoes a structured verification protocol specific to the platform's backplane bus architecture. CPU modules including the 6ES5947-3UA22 are tested under live STEP 5 program execution using a dedicated S5-115U test rack, verifying: program memory read/write integrity across the full 48 KB address space; battery-backed SRAM data retention after simulated power cycle; backplane bus communication at rated clock speed; and MPI port continuity. Analog I/O modules are calibrated against NIST-traceable reference instruments. Digital I/O modules are cycled through full channel-by-channel functional verification. Communication processors are tested for protocol handshake and data throughput under load. All modules are inspected for capacitor condition, connector pin integrity, and conformal coating status before dispatch.