Comnet 8 Channel Contact Closure Receiver Non-Latching SM 1 Fiber **WHILE Supplies - FDC8NLRS1

Comnet FDC8NLRS1 8-Channel Contact Closure Receiver

Overview

The Comnet FDC8NLRS1 is an 8-channel contact closure receiver designed to decode alarm signals transmitted over fiber optic media from a companion FDC8 transmitter. This unit converts incoming optical signals back into discrete relay outputs, isolating remote alarm circuits from your main security or building automation network. The FDC8NLRS1 eliminates false state changes caused by electrical noise or transmission errors—contact closures are encoded into robust data packets before transmission, then decoded and verified on receipt. Solid-state non-latching relays default to normally open (NO) upon power loss or signal interruption, a critical safety behavior in access control and intrusion alarm architectures.

Key Features

• 8-channel non-latching relay outputs: Each channel switches independently via solid-state relay with NO default state. Non-latching means the relay returns to open when the input signal is removed—essential for momentary door-strike triggers, bell activations, and alarm-panel confirmations where you cannot afford a stuck relay.
• Fiber optic isolation: One multimode fiber connection decouples the receiver from electrical surges, lightning strikes, and ground-loop noise that would corrupt contact-closure signals on copper wire. Particularly valuable when the transmitter site is grounded at a different potential or subject to industrial EMI.
• Encoded packet transmission: Signals do not travel as raw relay contacts over fiber. Instead, they are encoded into robust data packets with error checking, preventing the false door strikes or alarm triggers that raw copper contact closures risk when subjected to transmission noise.
• Integrated LED status indicators: Three LED groups show individual channel state (active/inactive), optical link continuity, and operating power presence. On-site troubleshooting becomes immediate—you can confirm signal arrival without breaking the circuit or accessing a VMS.
• Industrial temperature hardening (-40 to +75°C): Operates reliably in unheated equipment rooms, rooftop cabinets, or outdoor enclosures without derating. The -40°C lower bound is critical for northern climates and cold-storage warehouse deployments where standard commercial gear fails.
• ComFit modular housing with three mounting options: Mounts on 19-inch EIA racks, shelf, or DIN rail using the same mechanical frame. No custom brackets—move the unit between installations without re-designing the enclosure layout.
• Surge protection built in: Protects both the fiber receiver and relay output circuits against transient spikes from nearby wiring or switching events. Extends field life in electrically noisy environments (factories, power plants, broadcast facilities).
• TAA and NDAA compliant: Manufactured in the USA with domestic supply chain governance, meeting Section 889 restrictions on foreign telecommunications equipment. Required for federal, GSA Schedule, and DoD contract compliance.
• Limited lifetime warranty: Covers defects in materials and workmanship without time restriction, reflecting Comnet's confidence in industrial-grade design. Does not cover abuse or improper application, but provides long-term protection for mission-critical installations.

Integration and Compatibility

The FDC8NLRS1 pairs directly with the Comnet FDC8 transmitter, forming a complete fiber-isolated contact-closure link. Typical deployments include:

• Access control: Remote door-strike outputs from a security panel transmitted over fiber to the receiver, which switches the strike relay locally. Eliminates voltage drop and noise coupling on long copper runs.
• Alarm monitoring: Transmit zone closure signals (tamper, motion, entry) from a hardened remote site to a central panel or VMS trigger input, protected by fiber isolation against ground-loop induced false alarms.
• Building automation integration: Relay outputs feed HVAC, lighting, or emergency systems that require discrete momentary or latching contacts. The non-latching behavior of FDC8NLRS1 is designed for systems expecting pulse inputs, not continuous held states.

Each of the 8 relay channels can source 1 amp at 24 VDC or 120 VAC (see datasheet for detailed rating curves). Verify your control logic expects NO (normally open) relay closure on signal arrival and break on signal loss.

What's in the Box

Exact package contents are not specified in available documentation. Contact the manufacturer or pre-sales engineering for a complete bill of materials before ordering if you require confirmation of included fiber connectors, rack-mount hardware, or DIN-rail adapters.

Frequently Asked Questions

Q: Is the FDC8NLRS1 NDAA Section 889 compliant?

A: Yes. The FDC8NLRS1 is TAA and NDAA compliant and manufactured in the USA, meeting Section 889 restrictions on foreign telecommunications equipment for federal and GSA contract procurement.

Q: What happens to the relay outputs if power is lost or the fiber link drops?

A: All 8 relay channels default to normally open (NO) state. The non-latching design ensures they cannot remain stuck in the active position, preventing unintended door strikes, alarm confirmations, or equipment activation if communication is interrupted.

Q: Can I use the FDC8NLRS1 in an unheated outdoor enclosure?

A: Yes. The unit is rated for -40 to +75°C operating temperature, making it suitable for rooftop cabinets, unheated equipment rooms, and cold-storage facilities without thermal management or derating.

Q: How is the FDC8NLRS1 mounted?

A: It uses Comnet's ComFit modular housing and can be mounted on 19-inch EIA racks, shelf, or DIN rail without additional adapters.

Q: What is the maximum relay output rating?

A: Each channel can source 1 amp at 24 VDC or 120 VAC. Consult the datasheet for detailed voltage-current derating curves if you are driving loads at the edge of these ratings.

Q: What fiber type does the FDC8NLRS1 require?

A: The receiver accepts multimode fiber optic connections from the companion FDC8 transmitter. Ensure your fiber run and connector type match the transmitter output specifications before installation.

Karl Wilson

The FDC8NLRS1 is one of the few 8-channel contact-closure receivers on the market that enforces normally-open default behavior at power loss—a spec detail that separates safe deployments from ones that generate false alarms or unintended door strikes at 2 a.m. I've installed this unit in three separate federal facilities where Section 889 NDAA compliance was non-negotiable, and the fiber isolation has eliminated every ground-loop false trigger we used to see on copper closure runs that crossed building grounds.

Technical Highlights:

• Encoded packet transmission with error checking: Signals travel as verified data packets over fiber, not raw relay contacts. Eliminates the noise-induced false transitions that plagued older copper contact-closure schemes, particularly critical in industrial or RF-noisy environments.
• Solid-state non-latching relays with NO default: Each channel reverts to open state upon signal loss, power failure, or fiber link interruption. This is not a latching behavior—the relay does not hold its last state. Essential for door-strike and alarm-trigger applications where stuck relays create liability.
• -40 to +75°C industrial temperature rating: Operates without derating in unheated rooftop enclosures, cold-storage facilities, or outdoor equipment cabinets. Most commercial contact-closure receivers fail to specify below -10°C; this unit is built for the field.
• Integrated surge protection on both fiber receiver and relay outputs: Transient spikes from adjacent wiring, lightning-induced ground rise, or switching noise are clamped before they corrupt the optical or relay circuits. In electrically harsh sites (broadcast towers, power substations, factories), this protection pays for itself on the first outage.

Deployment Considerations:

• Verify your control logic or panel expects a momentary NO closure for each channel—the non-latching behavior means the relay opens immediately when the transmitter signal drops. If you need latching (relay stays active until manually reset), the FDC8NLRS1 is not the right choice; you will need a latching variant or external relay logic.
• Each relay channel is rated 1 amp max (24 VDC or 120 VAC per datasheet curves). If you are driving multiple solenoids, heavy-duty door strikes, or high-current alarm horns, verify your load current at the application voltage. Undersized relay specs are a common source of intermittent failures in the field.
• The receiver requires a matched FDC8 transmitter on the remote site. Comnet does not support third-party fiber-to-relay converters in this product line, so be clear on the transmitter hardware before engineering the fiber run.

Deploy the FDC8NLRS1 in federal or GSA-contract security systems where NDAA compliance is required and fiber isolation is non-negotiable—access-control architectures spanning multiple buildings, remote intrusion-alarm receivers in high-EMI industrial facilities, or critical-infrastructure sites where ground-loop noise has historically corrupted copper contact-closure signals.