Yokogawa SNB10D-243 S2 Safety Node Unit

Product Parameters

• Model Number: SNB10D-243 S2
• Manufacturer: Yokogawa Electric Corporation
• System Series: ProSafe-RS (Safety Instrumented System)
• Node Type: Safety Node Unit (SNU)
• Power Supply: 240 Vac (indicated by the “-2” suffix)
• Communication Interface: Dual-redundant ESB Bus (S2 configuration)
• I/O Slot Capacity: 10 slots for safety I/O modules
• Redundancy: Supports redundant power supply and communication modules

Product Description The SNB10D-243 S2 is a fundamental hardware component of the Yokogawa ProSafe-RS Safety Instrumented System (SIS). It serves as a ruggedized enclosure and communication hub for safety-critical I/O modules. The “S2” version denotes the enhanced performance and reliability standards required for modern industrial safety applications. This unit facilitates high-speed, deterministic data exchange between field sensors and the safety control station via the ESB bus. Designed with internal hardware diagnostic capabilities, it ensures that the system can achieve and maintain Safety Integrity Level 3 (SIL3) in accordance with IEC 61508 standards.

Product Applications This safety node is primarily deployed in high-risk industrial environments such as oil and gas refineries, petrochemical plants, and large-scale power generation facilities. It is utilized for Emergency Shutdown (ESD) systems, Fire and Gas (F&G) monitoring, and Burner Management Systems (BMS). The SNB10D provides the distributed architecture necessary to monitor remote field devices and execute safety logic independently of the standard distributed control system (DCS).

Product Specifications

• Weight: 6.50 kg (approx. without modules)
• Dimensions: 13.0 cm x 48.3 cm x 25.0 cm (Standard 19-inch rack mount)
• Country of Origin: Japan
• Operating Temperature: 0°C to +50°C

Operational Precautions

• Bus Termination: Ensure the ESB bus is correctly terminated at the final node in the chain to prevent signal reflections that can cause intermittent safety system communication errors.
• Module Seating: When inserting safety I/O modules into the 10 available slots, ensure they are firmly seated and locked; a loose module can trigger a system-wide diagnostic alarm or a partial safety shutdown.
• Grounding Protocol: Maintain a dedicated safety ground separate from the functional/instrument ground to prevent electrical noise from interfering with sensitive safety-critical signals.
• Voltage Verification: As this is a 240 Vac model, verify the local mains voltage before applying power to avoid damaging the internal power supply units (PSUs).

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