Model Interpretation

3504E: High‑Density TMR Digital Input Module, 24/48VDC, 64‑point, commoned

TMR: Triple Modular Redundancy (core architecture, always included)

P/N: 3504E (no separate “TMR” suffix)

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

Key Feature: 64 channels (no channel‑to‑channel isolation), DC‑coupled, 20–72VDC range

Technical Parameters

Electrical & Input

Input Type: Dry/wet contact, DC‑coupled (24VDC or 48VDC nominal)

Voltage Range: 20–72VDC (max 72VDC)

Channels: 64, commoned (non‑isolated channel‑to‑channel)

Input Current: 2–3mA (on‑state)

Hysteresis: 4VDC (24V range) / 7VDC (48V range)

Backplane Power: 24VDC (20.4–28.8VDC), ~180mA

Isolation: Field‑to‑backplane galvanic isolation (1,500VDC); no channel‑to‑channel isolation

Redundancy & Safety

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

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

Diagnostics: >99.9% fault coverage; ON/OFF stuck‑test; SOE (≤40ms resolution)

MTBF: >140,000 hours

Mechanical

Form Factor: 3U, 19” rack, 1 slot

Dimensions (W×H×D): 114 × 30 × 185 mm

Weight: ~2.0 kg (4.4 lbs)

Mounting: Plug‑in backplane, hot‑swappable

Color Code: Dark Red

Environmental

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: Open/short circuit, TMR deviation, stuck‑state (ON/OFF)

Core Functions

64‑Point High‑Density 24/48VDC Safety Input

Accepts 20–72VDC signals (ESD pushbuttons, limit switches, F&G detectors); 64 commoned channels minimize slot usage for large safety systems.

TMR Fault‑Tolerant Voting

Three independent input circuits per signal; 2oo3 voting eliminates single‑point failures—critical for SIL3 ESD/F&G/BMS loops.

Stuck‑Test for ON/OFF State Verification

Built‑in self‑test verifies detection of both “stuck‑on” and “stuck‑off” faults, enhancing safety for both energize‑to‑trip and de‑energize‑trip circuits.

Hot‑Swap & Online Maintenance

Replace module without system shutdown; supports online diagnostics and SOE logging for compliance.

Wide Voltage Range & Noise Immunity

20–72VDC range covers both 24V and 48V field devices; opto‑isolation rejects ground loops and electrical noise.

Applications

Oil & Gas: Large‑scale ESD/F&G systems; high‑count 24/48V safety switches

Chemical/Refining: Complex process interlocks; dense discrete safety signal arrays

Power Generation: Turbine ESD; boiler BMS with numerous safety interlocks

SIS Retrofits: Maximize I/O capacity in existing Tricon chassis; reduce slot count for large loops