The Yokogawa SNT411 is an Optical ESB Bus Repeater Master Module used in Yokogawa ProSafe-RS Safety Instrumented Systems (SIS).
It is designed to convert ESB bus electrical signals into optical fiber signals, enabling long-distance communication between safety controllers, safety nodes, and I/O subsystems. It works together with a slave-side module (typically SNT511 or S2EN501 series) to form a complete optical transmission path.
The SNT411 is a core device for building large distributed safety networks using ESB optical bus architecture.
Technical Specifications
| Parameter | Specification |
|---|---|
| Brand | Yokogawa |
| Model | SNT411 |
| Product Type | Optical ESB Bus Repeater (Master) |
| System Compatibility | ProSafe-RS / ESB bus architecture |
| Function | ESB electrical → optical signal conversion |
| Pairing Module | SNT511 / S2EN501 |
| Network Type | ESB optical fiber communication |
| Topology | Star type / Chain type |
| Max Connection Stages | 2 stages |
| Transmission Distance | Up to 5 km per segment, up to ~50 km total (2-stage system) |
| Current Consumption | ~0.5 A |
| Weight | Approx. 0.3 kg |
| Operating Temperature | -20°C to +70°C (ISA G3 class, typical) |
| Installation | 19-inch rack system module |
The module is designed to extend ESB bus communication using fiber optics while maintaining deterministic real-time behavior required for safety systems.
Physical Characteristics
| Item | Specification |
|---|---|
| Dimensions (W × H × D) | Approx. 32.8 × 130 × 142.5 mm |
| Weight | ~0.3 kg |
| Mounting Type | 19-inch industrial rack |
| Structure | Optical repeater master board |
| Installation | SIS control cabinet |
System Role
The SNT411 is the master-side optical interface in ESB bus expansion systems.
Typical architecture:
-
ESB bus from controller (SEC401 / SSB401 / SSC systems)
→ SNT411 (Master)
→ Optical fiber link
→ SNT511 / SNT10D side (Slave / repeater side)
→ Remote safety node (SNB / I/O modules)
This enables long-distance distributed safety system communication with high reliability.
Recommended Related Models
- Yokogawa SNT511 – Optical ESB Bus Repeater Slave
- Yokogawa SNT10D – ESB repeater rack unit
- Yokogawa SNT401 – earlier master variant
- Yokogawa SNB10D – safety node unit
- Yokogawa SEC401 / SEC402 – ESB coupler modules
