TRICONEX 3351S2 (AI3351S2) Analog Input Module
Product Description
TRICONEX 3351S2 is an analog input module built with TMR Triple Modular Redundancy architecture for TRICONEX Safety Instrumented System (SIS). It mainly collects 4‑20 mA analog signals from field transmitters, converts field process variables into digital signals and transmits them to the controller for safety logic execution.
TRICONEX 3351S2 incorporates three sets of isolated independent circuits. Data filtering is completed via voting mechanism; median value is output under TMR mode while average value is output under dual‑mode. Single‑channel fault will not interrupt overall module operation.
AI3351S2 features 32 common inputs with fast scanning speed and full channel‑level diagnostics. It is widely applied in safety interlock, emergency shutdown and fire‑gas monitoring for high‑risk process industries. TRICONEX 3351S2 supports hot‑standby module configuration for online faulty‑module replacement to reduce plant shutdown risks.
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Technical Specifications
| Parameter | Specification |
|---|---|
| Input Points | 32 common inputs |
| Rated Input Current | 4‑20 mA DC |
| Valid Operating Current Range | 2‑22 mA DC |
| Maximum Absolute 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‑V Sampling Resistor | 100 Ω ±0.01% |
| Resolution | 12 bit |
| Absolute Error | 0.15% of full scale (20mA) |
| Diagnostic Function | Force‑to‑Value Diagnostic (FVD) |
| Full‑32‑point Scan Time | ＜1 ms |
| Isolation: Functional Ground to Protective Ground | Minimum 500 VDC |
| Isolation Between Functional Grounds (Logic Side) | Minimum 800 VDC |
Core Advantages
Triple‑modular TMR fault‑tolerant architecture. Three independent channels perform acquisition and computation. Continuous operation is maintained upon single‑channel fault to meet high‑fault‑tolerance requirements of safety instrumented systems.
High‑density 32‑point signal acquisition. Full‑channel scan time is less than 1 ms for fast acquisition of process parameters.
Comprehensive channel‑level on‑board diagnostics. Fault LED only indicates channel abnormality instead of overall module failure. Continuous operation is available under multi‑fault conditions.
Hot‑standby module configuration supported. Module replacement can be completed without system shutdown to minimize unplanned plant downtime losses.
Sufficient electrical isolation rating resists industrial‑site surge and common‑mode interference to guarantee stable 4‑20 mA signal acquisition.
Mechanical anti‑keying design prevents mis‑installation of AI3351S2 into baseplate slots and lowers human errors during field wiring and commissioning.
Product Features
Each field input of TRICONEX 3351S2 is independently processed and acquired by three sets of isolated electronic circuits, followed by data voting in the processor.
The module is equipped with Force‑to‑Value (FVD) diagnostic to continuously inspect every channel. Once channel abnormality is detected, fault LED illuminates and system alarm is triggered.
This fault alert only indicates channel failure; the TRICONEX 3351S2 module itself remains operational. Full functionality is retained under single‑fault conditions, and continuous operation is achievable for certain multi‑fault scenarios.
Mechanical locking on baseplates only accepts compatible bases. Hot‑spare redundancy is supported; faulty modules can be replaced online without cutting off external field loop signals. Certain baseplate versions enable HART field instrument communication with PC‑based asset management configuration software.
Application Fields
- Oil & Gas: ESD emergency shutdown system, Fire & Gas (F&G) system, pressure, flow and level signal acquisition for pipeline compressor stations.
- Refining & Petrochemical: Reactor safety interlock, process unit safety monitoring, receiving 4‑20 mA signals from pressure, level and flow transmitters.
- Power Industry: Unit protection interlock, safety instrument signal acquisition for boilers and steam turbines.
- High‑risk Process Industries: HIPPS High‑Integrity Pressure Protection System, automation projects requiring SIL3‑grade safety acquisition.
Product Comparison
Model Type Channel Scale Key Differences 3351S2 Analog Input AI 32 common‑input points 4‑20mA High‑density current acquisition, FVD diagnostics, TMR architecture, compatible with standard and HART‑enabled baseplates 3700A Analog Input AI 32 differential points Supports voltage‑signal input, differential coupling, no HART capability 3703E Analog Input AI 16 isolated points Channel‑to‑channel isolation, suitable for heavy‑interference sites, fewer channels 3481S2 Analog Output AO 8 points Analog output card, outputs 4‑20mA to drive field valve actuators
Compatible Products
Matching Baseplates
- 2351: Direct‑fit baseplate for TRICONEX 3351S2 under standard 4‑20 mA operating conditions.
- 2354S2: For 4‑20 mA applications, supports communication between HART field devices and PC‑based asset‑management configuration software.
- 2354AS2: For 4‑20 mA hazardous‑area applications, enables HART instrument communication.
External Terminal Panels
- 9764‑510F RTD/TC/AI external terminal panel
- 9792‑310F AI hazardous‑area external terminal panel
FAQ
Q: Does TRICONEX 3351S2 support hot‑swap online module replacement?
A: Online faulty‑module replacement is available under hot‑spare configuration without controller shutdown, while compatible mating baseplates are required.
Q: Does illuminated fault LED on AI3351S2 mean the whole module is damaged and must be replaced?
A: Fault LED indicates single‑channel fault rather than complete module failure. Remaining channels can keep acquiring data when partial channels get damaged. Confirm fault sources via software diagnostics.
Q: Can TRICONEX 3351S2 directly accept thermocouple or RTD signals?
A: The module natively processes 4‑20 mA current signals only. Thermocouple / RTD signals require external conversion devices or signal‑conversion external terminal panels.
Q: Shall baseplates be ordered together when purchasing TRICONEX 3351S2?
A: Module and baseplate are separate part numbers. Confirm baseplate model during procurement: 2351, 2354S2 or 2354AS2.
Q: The ＜1 ms scan time for AI3351S2 applies to single channel or all 32 input points?
A: The ＜1 ms specified in technical documents refers to the overall scan cycle for all 32 input points instead of single‑channel scan duration.
Q: Is HART function built‑inside TRICONEX 3351S2 or implemented by mating baseplate?
A: HART communication depends on corresponding baseplates; no HART circuit is integrated on the module itself. Select 2354S2 or 2354AS2 baseplates for HART‑enabled applications.
Q: Within 2‑22 mA operating range, can transmitter outputs below 4 mA be recognized?
A: Hardware recognizes signals within 2‑22 mA. 4‑20 mA is the nominal transmitter range. Values below 4 mA usually indicate instrument faults, which shall be judged by upper‑level logic programs.
Q: For legacy‑system upgrade replacement, how to verify existing Tricon controller firmware compatibility with 3351S2?
A: Check TriStation software revision and controller firmware version. Import hardware configuration files to validate channel mapping before commissioning to avoid identification anomalies.
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Notes
- TRICONEX 3351S2 shall only be used with compatible mating baseplates with mechanical anti‑keying latches. Forced installation into mismatched slots is prohibited.
- Baseplate selection: use 2351 for standard conditions; select 2354S2 for HART instrument communication; select 2354AS2 for hazardous‑area HART applications.
- AI3351S2 only processes 4‑20 mA current signals. Thermocouple and RTD signals cannot connect directly to module terminals.
- Observe voltage limits for field wiring: maximum field voltage shall not exceed 33 VDC and reverse voltage shall not exceed ‑0.6 VDC to prevent channel‑circuit damage.
- Confirm hot‑spare configuration before performing online module replacement, and strictly follow system maintenance procedures.
- Validate hardware list and complete 32‑point channel mapping for 3351S2 inside TriStation software during project configuration.
Product Tags
TRICONEX 3351S2, AI3351S2, Analog Input Module, TMR AI Module, TRICONEX SIS I/O card, 4‑20mA input module, Safety Instrumented System I/O Module, Triple‑Modular‑Redundancy Analog Input Card, Tricon System Analog Input Module, 32‑point analog input card
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