Description
Product Overview
The Triconex 3351 is an Analog Input Module. It has 32 input points (commoned). Each module contains three isolated electronic channels. These channels process field data independently. They send data to three MPs for voting. In TMR mode, the system uses the mid-value. In dual mode, it uses the average.
Key Specs at a Glance
- Brand: Triconex
- Model: 3351
- Product Type: Analog Input Module (TMR)
- Number of Points: 32 (commoned)
- Input Current: 4-20 mA DC (nominal)
- Operational Range: 2-22 mA DC
- Resolution: 12 bits
- Scan Time: <1 ms for all 32 points
- Absolute Error: 0.15% of full scale (20 mA)
Electrical Limits
- Maximum field voltage: 33 VDC
- Maximum reverse field voltage: -0.6 VDC
- Maximum input current: 50 mA DC
- Input bandwidth (3dB): 16 Hz
- Source impedance: 180 Ω
- Input impedance (with baseplate): 250 Ω
- I to V resistor: 100 Ω ±0.01%
Isolation Ratings
- Functional earth to protective earth: 500 VDC minimum
- Functional earth to logic functional earth: 800 VDC minimum
Supported Baseplates
- Model 2351 – For typical 4-20 mA applications
- AI External Termination Baseplate – Works with Model 9764-510 RTD/TC/AI panel or Model 9792-310 hazardous location panel
- Model 2354 – 4-20 mA with HART communication support
- Model 2354A – 4-20 mA with HART for hazardous locations
Diagnostic Features
- Complete ongoing diagnostics for each channel
- Fault indicator lights up when a channel fails
- Fault means a channel problem, not a full module failure
- Module works properly with a single fault (fault-tolerant)
- May continue working with multiple faults
- Diagnostic Force-to-value (FVD) feature included
Reliability Features
- Supports hot-spare module for redundancy
- Mechanically keyed to prevent wrong installation
- Triple Modular Redundancy (TMR) for high availability
AI/DI Variant Note
- The Analog Input/Digital Input Module has 16 digital points (1-16) and 16 analog points (17-32)
- Three isolated channels process data independently
- One channel failure cannot affect another channel
- Analog points: variable voltage signals converted to digital values
- Digital points: ASIC scans each input point and sends to MPs
Installation Guide
- Select the correct baseplate (2351, 2354, 2354A, or AI External Termination)
- Install the baseplate in the Tricon chassis
- Slide the 3351 module into the baseplate
- The keying mechanism prevents wrong insertion
- Tighten the front panel screws
- Connect field wiring to the termination panel
Debugging & Maintenance
- Check the Fault indicator LED for channel problems
- A Fault LED does not mean the whole module is bad
- Use the hot-spare module for online replacement
- System alarm activates when diagnostics find a failure
- Scan all 32 points in less than 1 ms for fast debugging
Compatibility
- Works with all Tricon systems that support analog input modules
- Compatible with Modicon Quantum PLCs via system integration
- HART communication available when using baseplate 2354 or 2354A
- Works with Configuration and Asset Management Software on a PC
Typical Applications
- 4-20 mA sensor monitoring in safety-critical systems
- Oil and gas process control with TMR fault tolerance
- Power generation analog signal acquisition
- Chemical plants requiring high reliability
- HART device integration for asset management
- Hazardous location installations (with 2354A baseplate)
Professional FAQ
- What does the Fault LED mean on a Triconex 3351?
It means one of the three internal channels has a problem. The module can still work correctly with one fault. - Can I replace a faulty 3351 module while the system runs?
Yes. The module supports a hot-spare. You can replace it online without shutting down. - What is the difference between TMR mode and dual mode?
TMR mode passes the mid-value of three channels. Dual mode passes the average of two channels. - Do I need a special baseplate for HART communication?
Yes. Use baseplate 2354 or 2354A. Standard 2351 baseplate does not support HART. - What happens if input current goes above 22 mA?
The module accepts up to 50 mA absolute max. But accuracy is only guaranteed from 2 to 22 mA.
Experience-Based Q&A
- Our 3351 shows a Fault LED but readings look normal. Should we replace it?
Not immediately. The module tolerates one fault. Plan to replace it during the next scheduled shutdown. - We need faster than 16 Hz response. Can we adjust the bandwidth?
No. The 3dB bandwidth is fixed at 16 Hz. Use a different module for high-speed signals. - We connected a 2-wire transmitter but get no reading. What is wrong?
Check if you need an external loop power supply. The 3351 does not provide loop power. - Can we mix 3351 modules with older 3350 modules in the same chassis?
Yes, but check system firmware compatibility. Mixed modules may need same scan time settings. - Our analog readings drift over time. How do we fix this?
Use the Diagnostic Force-to-value (FVD) feature to test each channel. Then recalibrate the input range.
Selection Guide
- Choose Triconex 3351 for 32 analog points with TMR fault tolerance
- Need both analog and digital inputs? Pick the AI/DI variant (16 analog + 16 digital)
- Need HART communication? Select baseplate 2354 (general) or 2354A (hazardous)
- For hazardous locations with HART, choose 2354A baseplate
- For basic 4-20 mA without HART, choose baseplate 2351
- Need external RTD/TC inputs? Use the AI External Termination Baseplate with Model 9764-510 panel
Warranty & Shipping
- Warranty: 12 months from shipment date. Covers defects.
- Shipping: FedEx, UPS, DHL. Express options available.
For inquiries: +86 158 8020 0923
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