The TRICONEX 3704E is a TMR (Triple Modular Redundant) High-Density Analog Input Module for Tricon safety systems. It accepts voltage or current signals and provides redundant analog signal processing for safety-critical control applications. Tricon system documentation identifies the 3704E as a 64-point, commoned, DC-coupled analog input module with 0–5 VDC or 0–10 VDC input ranges.
The module uses three redundant processing paths to support fault-tolerant operation. Its input range can be configured through TriStation 1131, making it suitable for different analog instrumentation requirements within a compatible Tricon chassis.
Key Features
- TRICONEX Trusted/Safety System I/O
- 3704E TMR Analog Input Module
- 64 analog input points
- Commoned, DC-coupled inputs
- 0–5 VDC or 0–10 VDC input range
- 0–20 mA operation with external shunt resistor
- 12-bit resolution
- 75 ms input update rate
- TMR architecture
- PASS / FAULT / ACTIVE status indication
- Designed for continuous industrial safety applications
Product Datasheet
| Parameter | Specification |
|---|---|
| Brand | TRICONEX |
| Model | 3704E |
| Product Type | TMR Analog Input Module |
| Architecture | Triple Modular Redundant (TMR) |
| Input Points | 64 |
| Input Configuration | Commoned, DC-coupled |
| Voltage Range | 0–5 VDC / 0–10 VDC |
| Current Range | 0–20 mA |
| Current Interface | 250 Ω shunt for 5 V / 500 Ω shunt for 10 V |
| Resolution | 12 bits |
| Input Update Rate | 75 ms |
| Accuracy | <0.25% of FSR, 0–60°C |
| Input Resistance | 30 MΩ minimum |
| Power-Off Resistance | 30 kΩ typical |
| Channel-to-Channel Isolation | 200 kΩ typical |
| Overrange Protection | 150 VDC / 115 VAC continuous |
| Diagnostics | PASS / FAULT / ACTIVE |
| Color Code | Copper |
| Configuration | TriStation 1131 |
| Mounting | Tricon chassis |
These specifications are consistent with the Tricon v9–v11 technical documentation.
Functional Description
The 3704E receives analog signals from field instrumentation and processes them through the Tricon system’s redundant architecture. The module’s three processing legs provide the signal redundancy required by the TMR safety architecture.
For voltage applications, the module supports 0–5 VDC or 0–10 VDC. Current signals from 0–20 mA transmitters can also be accommodated using the appropriate external shunt resistor.
The module is intended to be installed in a compatible Tricon chassis and should not be treated as a standalone analog input card.
Typical Applications
- Emergency Shutdown Systems (ESD)
- Safety Instrumented Systems (SIS)
- Oil & gas processing
- Chemical plants
- Power generation
- Turbine protection
- Compressor protection
- Process monitoring
- Critical analog instrumentation
Installation & Configuration
- Verify the module marking 3704E.
- Confirm the Tricon chassis and system version.
- Check the existing I/O configuration in TriStation 1131.
- Identify each field-channel connection.
- Confirm whether the application uses voltage or current signals.
- Install the module in the correct keyed chassis position.
- Connect the appropriate field termination assembly.
- Verify configuration and channel assignments.
- Power up and check PASS, FAULT, and ACTIVE indicators.
- Perform analog loop testing.
- Compare the three redundant signal paths.
- Complete the safety-system functional test.
Commissioning Checklist
- Confirm 3704E model
- Verify chassis compatibility
- Check keying and seating
- Inspect field termination
- Verify signal range
- Check shunt resistor selection for current inputs
- Verify TriStation configuration
- Check PASS indicator
- Check FAULT indicator
- Check ACTIVE status
- Test all required analog channels
- Verify redundant signal processing
- Record commissioning results
⚠️ Important Replacement Note
There is incorrect information circulating online about the 3704E. Some third-party listings describe it as a 16-channel isolated analog module, but the Tricon technical documentation identifies the 3704E as a 64-point commoned TMR analog input module.
Do not confuse the 3704E with the closely related 3720 or 3721 modules. Their input configurations are different: the 3720 provides 64 single-ended isolated inputs, while the 3721 provides 32 differential DC-coupled inputs.
Ordering Information
TRICONEX 3704E | TMR Analog Input Module | 64-Channel Analog Input | 0–5/0–10 VDC | 0–20 mA | Tricon Safety System
