TRICONEX 3721 Analog Input Module
TRICONEX 3721 is a Triple Redundancy (TMR) analog input module under Schneider Electric’s Triconex brand, designed specifically for Safety Instrumented Systems (SIS), Emergency Shutdown Systems (ESD), and Fire and Gas Systems (F&G). It complies with the IEC 61508 SIL 3 safety level and is primarily used for high reliability acquisition and conversion of industrial field analog signals.

1、 Core parameters
Channel configuration: 32 differential inputs, DC coupling.
Signal type:
Voltage: 0-5 VDC (unipolar), ± 5 VDC (bipolar).
Current: 0-20 mA (with an external 250 Ω shunt resistor).
Performance indicators:
Update rate: 10 ms.
Resolution: 12 bit/14 bit programmable.
Accuracy: better than 0.15% FSR within the range of 0-60 ℃.
Common mode rejection ratio: ≥ 85 dB (DC-100 Hz).
Electrical protection: The input can withstand continuous overvoltage of 150 VDC/115 VAC, with channel isolation of 420 k Ω.
Working environment: Temperature range of -40 ℃ to+60 ℃, suitable for harsh industrial scenarios.
2、 Key characteristics
TMR Triple Redundancy: Internal three independent circuits for synchronous acquisition and majority voting, single channel failure does not affect system operation, with extremely high availability and safety.
High density acquisition: 32 channel design, compatible with parallel access of multiple sensors such as temperature, pressure, and flow.
Complete diagnosis: equipped with running/fault/activation/on-site status indicator lights, supporting module level self diagnosis and status monitoring.
Safety certification: Through SIL 3 certification, it meets the functional safety requirements of high-risk industries such as petroleum, chemical, and power.
3、 Typical applications
Widely used in key process control scenarios such as oil and gas, chemical, power, and offshore platforms, as the core I/O module of SIS/ESD systems, it collects on-site analog signals and transmits them to the controller to ensure production safety and continuous operation.