Model Interpretation

3721: 32‑Ch TMR Analog Input, differential, ±5V / 0–5V, 12/14‑bit

P/N: 3721

Compatibility: Tricon v9–v12 chassis (8110/8111/8112/8115/8116); hot‑swappable

Key Difference from 3700: ±5VDC bipolar range (vs. 0–5V unipolar on 3700); programmable resolution

Technical Parameters

Electrical & Input

Input Type: Differential, DC‑coupled

Voltage Ranges: 0–5VDC (unipolar) or ±5VDC (bipolar)

Channels: 32, differential (non‑isolated channel‑to‑channel)

Resolution: 12‑bit or 14‑bit programmable

Accuracy: <±0.15% FSR (0–60°C)

Input Impedance: ≥30MΩ (DC)

Common‑Mode Rejection: ≥−85dB (DC–100Hz)

Response Time: 10ms update rate (all channels)

Backplane Power: 24VDC, ≤15W (full load)

Isolation: 1,500VDC field‑to‑backplane galvanic isolation

Input Protection: 150VDC / 115VAC continuous

Redundancy & Safety

Architecture: Triple Modular Redundancy (TMR), 2oo3 voting

Safety Certification: IEC 61508 SIL3, TÜV, UL, CE, ATEX, FM

Diagnostics: Per‑channel continuous diagnostics; fault coverage >99.9%; SOE ≤40ms

MTBF: >130,000 hours

Mechanical & Environmental

Form Factor: 3U, 19” rack, 1 slot

Dimensions (W×H×D): 114 × 30 × 185 mm

Weight: ~1.36 kg (3.0 lbs)

Color Code: Dark Red (same as 3700/3700A)

Operating Temp: −40°C to +70°C

Storage Temp: −40°C to +85°C

Humidity: 5%–95% RH, non‑condensing

Diagnostics & Indicators

LEDs: PASS, FAULT, ACTIVE, TMR, ALARM

Fault Detection: Over/under‑range, TMR deviation, channel fault, resolution mismatch

Core Functions

32‑Channel Bipolar/Unipolar Voltage Input

Selectable ±5VDC (bipolar) or 0–5VDC (unipolar) ranges; ideal for transmitters with offset or bidirectional signals.

Programmable High Resolution (12/14‑bit)

Switch between 12‑bit (fast) and 14‑bit (high‑precision) to balance speed and accuracy in safety loops.

TMR Fault‑Tolerant Signal Acquisition

Three independent circuits with 2oo3 voting; eliminates single‑point failures for SIL3 ESD/F&G/BMS applications.

High Noise Immunity & Isolation

1,500VDC isolation and −85dB CMRR suppress ground loops and EMI in harsh industrial environments.

Hot‑Swap & Online Maintenance

Replace module without shutdown; per‑channel diagnostics and SOE logging support IEC 61511 compliance.

Applications

Oil & Gas: ESD/F&G systems; bipolar pressure/flow transmitters (±5V) on platforms

Chemical/Refining: HIPPS loops; reactor/column analog monitoring with offset signals

Power Generation: Turbine ESD; boiler BMS with bidirectional sensor outputs

SIS Retrofits: High‑density bipolar/unipolar AI in existing Tricon chassis