Model Interpretation

3505E: Enhanced Digital Input (EDI), 24VDC, 32‑point, TMR, wire‑break detection

P/N: 3505E (base)

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

Key Feature: 32 channels (8 groups × 4 commoned), 24VDC, wire‑break (open‑circuit) detection

Technical Parameters

Electrical & Input

Input Type: Dry/wet contact, 24VDC only (no AC)

Voltage Range: 20–42.5VDC (max 42.5VDC)

Channels: 32, commoned in 8 groups (4 channels/group), group‑isolated

Input Current: ~6mA (on‑state)

Backplane Power: 24VDC (20.4–28.8VDC), ~150mA

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

Special Feature: Wire‑break detection (open‑circuit monitoring for each channel)

Redundancy & Safety

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

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

Diagnostics: >99.9% fault coverage; SOE (≤40ms resolution); open/short detection + wire‑break alarm

MTBF: >150,000 hours

Mechanical

Form Factor: 3U, 19” rack, 1 slot

Dimensions (W×H×D): 114 × 30 × 185 mm

Weight: ~2.4 kg (5.3 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, WIRE‑BREAK

Fault Detection: Open/short circuit, TMR deviation, wire‑break (open‑circuit) per channel

Core Functions

24VDC Safety Input with Wire‑Break Detection

Designed for 24VDC field devices (ESD pushbuttons, limit switches, proximity sensors); unique wire‑break detection identifies broken wires or disconnected sensors—critical for high‑safety loops where open circuits pose risks.

TMR Fault‑Tolerant Voting

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

Group Isolation & Noise Immunity

8 isolated groups reduce cross‑talk; opto‑isolation rejects ground loops and electrical noise—suitable for oil/gas/chemical plants.

Hot‑Swap & Online Maintenance

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

Enhanced Diagnostics for Safety Compliance

Beyond standard open/short detection, per‑channel wire‑break monitoring ensures 100% visibility of field circuit health—ideal for IEC 61511 compliance.

Applications

Oil & Gas: ESD systems with 24V safety switches; F&G detectors requiring wire‑break monitoring

Chemical/Refining: Process interlocks with critical 24V discrete signals; HIPPS loops

Power Generation: Turbine ESD; boiler BMS with safety‑critical 24V sensors

SIS Retrofits: Upgrade 3503E systems to add wire‑break detection for higher safety integrity