Description
The ICS Triplex T3481A (manufactured under Rockwell Automation) is a 16-channel, 24 V DC high-density guarded digital output module designed for the Regent fault-tolerant control system. Engineered for high-availability and safety-critical applications, the module uses a dual-redundant internal architecture and an integrated Safetybus interface to ensure that no single internal failure can inadvertently apply power to an external field load.
Commercial Availability & Terms
- Condition: New Original (New Surplus) or Refurbished (Fully Bench Tested)
- Warranty: 12 months from delivery date
- Availability: In stock
- Lead Time: Ships within 1–3 business days via global couriers (DHL, FedEx, UPS)
- Pricing Note: Price subject to market conditions; contact us for a firm quote.
Technical Specifications
| Parameter | Value |
| Output Channels | 16 Guarded outputs, divided into 2 isolated groups of 8 channels |
| Operating Voltage | 24 V DC nominal field supply |
| Module Type | High-Density Guarded Output (Fail-Safe) |
| System Bus Interface | Triplicated Safetybus interface |
| Field to Logic Isolation | 250 V AC minimum electrical isolation |
| Line Monitoring | Automatic continuous sensing for open and short circuits |
| Fusing | Front-panel accessible individual fuses per channel |
| Diagnostics | Automatic background testing of all internal output switches |
| Status Indicators | Front panel LEDs for module fault/active status, shutdown state, individual output status, and load/fuse fault |
| Operating Temperature | 0 to +60 °C (+32 to +140 °F) |
| Weight | 1.82 kg (4.01 lbs) |
| Dimensions (H x W x D) | 265 mm x 32 mm x 358 mm |
Architecture & Safety Integrity Features
In field deployments of Regent systems, the T3481A is classified as a “Guarded” module due to its specialized fault-containment design. Unlike standard digital output cards, its primary engineering directive is to prevent dangerous uncommanded failures (spurious trips or failures-to-danger).
Safetybus Integration
The module communicates with the triplicated Regent processor chassis via three independent Safetybus lines. Output commands must be validated across these channels before the module updates its physical output stage, ensuring that a communication fault or backplane glitch does not trigger an incorrect field action.
Dual-Redundant Internal Switches
Each of the 16 channels features a dual-redundant series switch configuration. If an internal component fails short (welded state), the secondary supervisory switch acts as a circuit breaker to ensure the module can still de-energize the channel when commanded by the safety program.
Advanced Line Monitoring
The T3481A constantly executes automated background testing sequences to monitor the health of both the internal circuits and the external field wiring:
- Short Circuit Detection: Identifies abnormal current draw and reports a load fault before the downstream component damages the card.
- Open Circuit/Fuse Monitoring: Tracks the integrity of the loop even when the output is in the “Off” state via minimal trickle-current diagnostics. If a front-panel fuse blows or a field wire is severed, the corresponding front-panel LED illuminates immediately and passes the diagnostic flag to the application software.
Frequently Asked Questions
Can the T3481A be configured for fault-tolerant output operation?
Yes. Two T3481A Guarded Output modules can be wired in a parallel configuration to achieve full fault-tolerant control. In this setup, either module can be removed and hot-swapped under power without dropping the active field loads or disrupting the process.
What is the purpose of having two distinct output groups?
The 16 channels are divided into two independent groups of eight channels. This physical and electrical isolation allows plants to segregate different sub-systems or separate power distribution lines, preventing a catastrophic localized grounding fault on one field branch from disabling all 16 outputs simultaneously.
Does the T3481A handle 110 V AC or 120 V DC field loads?
No. The T3481A is strictly rated for 24 V DC field power supplies. If your application requires higher voltage thresholds, you must source the corresponding variants within the Regent Guarded Output product family designed explicitly for 110 V AC or 120 V DC interfaces. Always verify part number suffixes against the OEM system design manual prior to installation.
