The Triconex 3481 (commonly designated as AO3481) is an 8-channel Analog Output (AO) Module manufactured by Triconex (Schneider Electric / Invensys). Designed for high-availability Tricon Safety Instrumented Systems (SIS), the 3481 module provides current outputs to drive final control elements such as control valve positioners, variable speed drives, and actuators in critical safety applications up to SIL 3.
The AO3481 utilizes Triple Modular Redundant (TMR) architecture internally. Three independent signal legs receive commanded output values from the active main processors, vote on the correct output level, and drive a voting output circuit to ensure fault-tolerant operation without loss of function during single-point hardware failures.
Technical Specifications
| Parameter | Specification |
| Manufacturer | Triconex / Schneider Electric (Invensys) |
| System Platform | Tricon TMR Safety Instrumented System (v9 / v10) |
| Model / Part Number | 3481 (AO3481) |
| Module Type | TMR Analog Output Module |
| Output Channels | 8 isolated 4–20 mA DC channels |
| Output Current Range | 4 mA to 20 mA (extended 0 mA to 22 mA diagnostic range) |
| Resolution | 12-bit D/A conversion |
| Accuracy | \pm 0.15\% of full scale (25^\circC) |
| Safety Integrity Rating | SIL 3 Certified (IEC 61508 / IEC 61511) |
| Field Power Requirement | 24 V DC external field power supply |
| Operating Temperature | 0°C to +60°C (32°F to 140°F) |
Core Features & System Capabilities
- Triple Modular Redundant (TMR) Architecture: Features three isolated processing paths running parallel diagnostic algorithms, providing voter circuitry at the output stage to guarantee uninterrupted loop control.
- Online Hot-Swappability: Supports live module insertion and replacement in paired slot configurations without interrupting active safety loops or shutting down the chassis.
- Continuous Loop Diagnostics: Automatically tests output circuitry, field loop integrity, and internal D/A converters for open circuits, short circuits, or ground faults.
- Galvanic & Optical Isolation: Provides high isolation ratings between the backplane logic rail and field circuits to guard against electrical transients and ground loops.
- External Termination Panel (EGA/ETP) Interfacing: Connects to standard Triconex external termination panels via pre-fabricated cables for simplified field wiring and loop fusing.
Related Triconex Hardware Components
- 3482 / AO3482 — High-Density 16-Channel Analog Output Module.
- 3351 / AI3351 — 32-Channel TMR Analog Input Module.
- 3008 / 3009 — Tricon Main Processor Modules (SIL 3).
- 8312 / 8310 — Tricon High-Density Chassis Power Supply Units.
