Yokogawa ProSafe-RS Modules: PS31*A,

Technical Dossier

Product Details And Specifications

Yokogawa ProSafe-RS Series Technical Notes

The Evolution of ProSafe-RS Architecture

ProSafe-RS was introduced by Yokogawa in the early 2000s as a successor to its earlier safety relay and hardwired interlock systems, providing a programmable SIS platform with full IEC 61508 certification. The initial architecture used a dual-redundant CPU structure with dedicated safety buses isolated from the process control network. Subsequent generations introduced enhanced diagnostic coverage, faster scan times, and tighter integration with CENTUM VP via Vnet/IP. The PS31 power supply series (including PS31*A and PS31*B) represents the standardized 24 VDC power distribution modules used across multiple chassis generations. Compatibility between early and later ProSafe-RS chassis generations requires verification of firmware revision and backplane bus version before substitution. Modules from the SSC, SCP, SDV, SAI, and SDO families are not interchangeable across all chassis types without engineering review. As the platform has entered a mature lifecycle phase, Yokogawa continues to provide long-term maintenance support, but new production of certain modules has been discontinued, increasing reliance on certified refurbished and surplus inventory sources.

ProSafe-RS Full Catalog & Functionalities (SKU List)

The following SKUs represent the core module range of the Yokogawa ProSafe-RS platform, classified by functional category. All models listed are verified ProSafe-RS components.

Power Supply Modules

• PS31*A: 24 VDC redundant power supply module, standard chassis power distribution unit.
• PS31*B: 24 VDC power supply module, alternate revision with updated inrush protection circuitry.

Safety CPU / SIL Solver Modules

• SSC60D: Dual-redundant SIL 3 safety CPU module, 100 ms scan cycle, Vnet/IP interface.
• SSC57S: SIL 3 safety CPU, single configuration, for smaller safety loop counts.
• SSC50: Earlier-generation safety CPU module, compatible with first-generation ProSafe-RS chassis.
• SSC10: Entry-level safety CPU for low-density SIS applications, SIL 2 rated.

Safety Controller / Communication Modules

• SCP451: Safety communication processor, Vnet/IP to safety bus gateway, redundant configuration.
• SCP461: Enhanced safety communication processor with extended diagnostic logging.
• SB401: Safety bus interface module for inter-chassis communication in large SIS configurations.

Digital Output Modules

• SDV541: 16-channel 24 VDC digital output module, SIL 3 rated, short-circuit protected.
• SDV531: 8-channel 24 VDC digital output module, SIL 2/3, used in de-energize-to-trip circuits.

Analog Input Modules

• SAI143: 4–20 mA analog input module, 8 channels, HART pass-through, SIL 3.
• SAI133: 4–20 mA analog input module, 4 channels, earlier revision, SIL 2/3.

Digital Input Modules

• SDI147: 32-channel 24 VDC digital input module, SIL 3, high-density field wiring.
• SDI141: 16-channel 24 VDC digital input module, SIL 3, standard field termination.

Digital Output (Relay) Modules

• SDO144: 8-channel relay output module, SIL 3, used for final element actuation in ESD systems.
• SDO141: 4-channel relay output module, SIL 2/3, compact form factor for low-density applications.

Quality Control for the ProSafe-RS Range

ProSafe-RS modules incorporate complex safety backplane bus interfaces and dual-channel diagnostic circuitry that require specialized test procedures beyond standard functional checks. DriveKNMS applies the following verification steps to all ProSafe-RS inventory: (1) Visual inspection for backplane connector wear, capacitor condition, and conformal coating integrity. (2) Powered functional test using ProSafe-RS chassis with known-good CPU and bus configuration, verifying module enumeration, diagnostic status, and channel-level I/O response. (3) For CPU modules (SSC series), firmware version verification and memory integrity check. (4) For analog input modules (SAI series), calibration verification across the 4–20 mA range with HART communication test. (5) For power supply modules (PS31 series), load regulation test under rated current draw with ripple measurement. All tested units are labeled with test date, technician ID, and pass/fail record. Units that fail any stage are quarantined and not offered for sale.