Comnet 24-Channel Duplex Contact Closure Transceiver RS-422 Interface - FDC24NL

Comnet FDC24NL 24-Channel Duplex Contact Closure Transceiver

Overview

The Comnet FDC24NL is a 24-channel duplex contact closure transceiver designed to transmit alarm signals, relay outputs, and contact status over fiber-optic or copper RS-422 networks. This solves the distance and noise-immunity problem when your control signals need to travel beyond standard wired limits — whether you're integrating gate controllers, door sensors, or access systems into a remote monitoring or recording facility. The FDC24NL handles non-latching relay contacts and delivers automatic resettable solid-state current limiting, so a shorted output won't take down your entire I/O chain.

Compatibility

The FDC24NL pairs with Comnet's fiber-optic and copper transmission ecosystem. It works with access control systems, alarm panels, and video management systems that support RS-422 serial communication. The module is hot-swappable, allowing you to pull and replace individual units without shutting down the entire installation. Up to 12 FDC24NL units can be daisy-chained or networked together, scaling contact closure capacity from 24 channels to 288 channels in a single system. Mount it on DIN-rail, wall, or rack — standard in telecom and security equipment rooms.

Installation Notes

The FDC24NL meets NEMA TS-1/TS-2 and Caltrans specifications, making it suitable for outdoor telecom cabinets and highway infrastructure. Use twisted-pair RS-422 cabling for copper runs; SFP optical ports accept standard single-mode or multi-mode fiber modules depending on your transmission distance and environment. Automatic resettable current limiting protects the relays against faults — no manual reset or breaker cycling required. Confirm RS-422 termination (120-ohm resistors at network endpoints) to avoid signal reflections on longer runs.