Core parameters

Channels: 32 isolated digital inputs (DI), 8-point common ground grouping

Input signals: 24V DC high level (wet contacts)

Effective voltage: High level ≥ +18V; Low level ≤ +6V

Input current: Typical 5mA @ 24V

Redundancy architecture: TMR (triplication redundancy), 2oo3 voting

Isolation: Channel / backplane 2500V DC isolation; Group-to-group isolation

Diagnosis: Channel LED, open circuit / short circuit / power failure diagnosis

Module power supply: 24VDC ±10%

Power consumption: Approximately 8W

Operating temperature: -40°C ~ +70°C

Certifications: SIL3, CE, UL, CSA, ATEX Zone 2, TÜV

Installation: Tricon 19" I/O rack, hot-swappable

Size / Weight: Approximately 483×254×51mm / 1.8–2.3kg

Difference from 3503E (EN = Enhanced)

3503E: Standard type, 24V dry / wet contacts, diagnostic basic version

3503EN: Enhanced version

Stronger EMC / anti-interference

More complete channel-level diagnosis

Compatible with higher-density FTA

Better consistency in industrial temperature range

New orders are mainstream 3503EN

Quick comparison of DI in the same series

3501E: 32-point 115V AC/DC DI

3502E: 32-point 48V AC/DC DI

3503E/3503EN: 32-point 24V DC high-level DI

3504E: 32-point 24V DC dry contact DI

Typical applications

Chemical / Oil and Gas: 24V electromagnetic valve feedback, limit switch, ESD button, PLC interlock output

Power Plant / Metallurgy: 24V switches for boiler / turbine auxiliary equipment, combustion engine ignition, fire protection F&G signals

SIS/ESD: Critical safety circuits 24V active signal acquisition, building SIL3 interlock

General industry: Proximity switches, photoelectric switches, relay contacts, alarm panel input

Pairing list

CPU: 1600071‑001B (Tricon TMR CPU)

FTA: 3503EN dedicated 24V DI terminal board (32 points, 8-point common ground)

Same series: 3501E, 3502E, 3504E