Overview
The SAI533-H33/PRP is a safety-rated analog input module developed by Yokogawa for deployment within the ProSafe-RS safety instrumented system. It is engineered to acquire and process critical analog field signals with high integrity while supporting PRP (Parallel Redundancy Protocol) networking to eliminate single points of failure at the communication layer.
Designed for use in high-risk industrial environments, this module delivers deterministic performance, robust diagnostics, and long-term operational stability required for certified safety loops.
Functional Characteristics
The SAI533-H33/PRP provides sixteen independent analog input channels, each electrically isolated to prevent fault propagation and signal interference. The module is optimized for standard 4–20 mA current signals commonly used by safety transmitters measuring pressure, flow, level, and temperature.
Integrated PRP functionality compliant with IEC 62439-3 allows the module to operate on dual Ethernet networks simultaneously, ensuring zero-time recovery from network failures. Combined with ProSafe-RS system redundancy, this architecture supports SIL2 and SIL3 applications when correctly configured.
Key Technical Advantages
High-density 16-channel analog signal acquisition in a single safety module
Native PRP support for seamless network-level redundancy
High-resolution A/D conversion for accurate process value representation
Complete channel-to-channel and channel-to-system isolation
Online replacement capability without stopping the safety controller
Built-in diagnostics covering input status, wiring faults, and internal health
Clear front-panel LED indicators for maintenance and troubleshooting
Electrical and Performance Specifications
Input signal type: 4–20 mA current (safety transmitter compatible)
Number of inputs: 16 isolated channels
A/D conversion: 16-bit resolution typical of the SAI series
Input impedance: Optimized for loop-powered field devices
Isolation rating: Channel-to-channel and channel-to-bus galvanic isolation
Power supply: Logic and field power supplied via ProSafe-RS baseplate
Network and Safety Compliance
Network protocol: PRP (Parallel Redundancy Protocol)
Standard reference: IEC 62439-3
Safety integrity: Suitable for SIL2 / SIL3 safety functions in redundant systems
Diagnostics coverage: Supports safety integrity calculations and proof testing
Environmental and Mechanical Data
Operating temperature range: 0 °C to 55 °C
Storage temperature range: −40 °C to 70 °C
Relative humidity: 5–95% non-condensing
Cooling method: Natural air convection
Installation: ProSafe-RS FIO baseplate slot
Maintenance: Hot-swap supported under system power
Typical Applications
Emergency shutdown systems (ESD)
Fire and gas detection systems (F&G)
Critical process interlocks in oil & gas and petrochemical plants
Turbine and boiler protection systems in power generation
High-availability safety loops requiring network redundancy
FAQ
Q: What is the benefit of PRP in the SAI533-H33/PRP?
A: PRP allows the module to communicate over two independent Ethernet networks simultaneously, providing uninterrupted data flow even if one network fails.
Q: Can this module be used in non-redundant systems?
A: While the module can operate in various architectures, SIL2/SIL3 certification requires use within a properly designed redundant ProSafe-RS system.
Q: Is the module limited to 4–20 mA inputs only?
A: The primary supported signal type is 4–20 mA, which aligns with most safety-rated field transmitters used in SIS applications.
