Comnet 8 Channel Contact Closure Receiver Non-Latching MM 1 Fiber **WHILE Supplies - FDC8NLRM1

Comnet FDC8NLRM1 8-Channel Contact Closure Receiver

Overview

The Comnet FDC8NLRM1 is an 8-channel contact closure receiver designed to extend normally-open dry contact switching over a single multimode optical fiber link. Built for mission-critical remote switching — traffic signal control, gate operators, HVAC systems, SCADA networks, and fire/intrusion alarm systems — this microprocessor-based unit decodes contact closure packets transmitted from a companion Comnet FDC8 transmitter and energizes eight independent solid-state relay outputs. Unlike electromechanical relays, solid-state switching eliminates mechanical wear and delivers >100,000 hours MTBF, critical for unattended trackside or roadside deployments.

Key Features

• 8 Independent Relay Outputs: Each channel provides normally-open dry contacts rated 30 VDC, 0.700 Amp — enough to drive solenoids, gate motor controls, and signal drivers without additional switching hardware. If your application needs higher current, you'll need an external relay stage.
• 25 Millisecond Response Time: Maximum 25 msec closure latency ensures near-instantaneous remote control for time-critical systems like traffic actuators or emergency door unlock sequences. Microprocessor logic detects transmitted contact changes and maps them to relay states with minimal propagation delay.
• Solid-State Relay Architecture: No mechanical contacts means no chatter, no contact cleaning, no service intervals. Automatic resettable solid-state current limiters protect each channel from short-circuit faults and transient surges — the relay defaults to normally-open if power is lost or the optical link fails, a safety-critical default for unattended equipment.
• Multimode Fiber Over 16 km: Comnet FDC8NLRM1 receives on ST-connectorized multimode 62.5/125µm fiber with 16 dB power budget, supporting point-to-point ranges up to 16 km (10 miles). Fiber isolation eliminates ground loops and EMI noise that plague copper twisted-pair in industrial substations and roadside cabinets.
• NEMA TS-1/TS-2 and Caltrans Certified: Tested and validated for traffic signal control environments — ambient temperature swing, mechanical shock, vibration, humidity with condensation, and transient voltage protection all verified by independent lab. Rated -40°C to +75°C operating, -40°C to +85°C storage, the FDC8NLRM1 survives unconditioned outdoor cabinets without climate control.
• Flexible Mounting: Ships in ComNet ComFit housing for shelf or rack mount (1 U slot when racked); DIN-rail mounting available via optional DINBKT1 adaptor. Eight status LEDs indicate power, link continuity, and each channel relay state for rapid field diagnostics — no laptop required to confirm operation.
• 8–15 VDC Surface Mount or Rack-Powered: When shelf-mounted, draws only 150 mA at 8–15 VDC, leaving modest power overhead in battery-backed outdoor cabinets. Rack versions draw power from the enclosure supply, simplifying integration in modular installations.
• Lifetime Warranty: Comnet backs the FDC8NLRM1 with a lifetime manufacturer warranty, reflecting confidence in the solid-state design and component quality.

Integration & Compatibility

The FDC8NLRM1 is a point-to-point receiver — it requires the matching Comnet FDC8 transmitter on the far end of the fiber run to encode contact closures into optical packets. Input contacts accept 5 VDC, 0.5 mA normally-open dry closures (switches, relay outputs, PLC dry contacts). No adjustments or optical calibration are required; plug-and-play design means installation is limited to fiber routing, power wiring, and contact terminal connections. Industrial IPC-standard circuit board and potted construction ensure long-term field reliability in humid, vibration-prone environments.

FAQ

Q: What is the maximum distance the FDC8NLRM1 can operate over fiber?

A: 16 km (10 miles) on multimode 62.5/125µm fiber with the 16 dB power budget. Single-mode variants may extend this; contact the manufacturer for options.

Q: Can the FDC8NLRM1 relay outputs drive a 24 VDC solenoid directly?

A: Yes — the relay contacts are rated 30 VDC, 0.700 Amp, so a standard 24 VDC solenoid drawing under 0.7 A will operate directly without additional switching. Confirm your solenoid's inrush current does not exceed 0.7 A.

Q: What happens if the optical fiber link is cut or the transmitter loses power?

A: All relay contacts automatically return to normally-open (de-energized) state. This failsafe default is critical for safety-critical applications like gate interlocks and door unlock circuits.

Q: Does the FDC8NLRM1 require any configuration or firmware updates?

A: No — the unit is pre-configured and requires zero setup. Plug the fiber, apply power, and connect your contact inputs and relay loads. No software, no VMS integration, no network connectivity needed.

Q: What is the MTBF (Mean Time Between Failures) of the FDC8NLRM1?

A: >100,000 hours — significantly longer than electromechanical relay banks, reducing field service calls in remote unattended locations.

Q: Is the FDC8NLRM1 suitable for outdoor roadside or trackside cabinets?

A: Yes — rated -40°C to +75°C operating and certified to NEMA TS-1/TS-2 and Caltrans specifications for traffic signal and railway control environments. Voltage transient protection and solid-state design handle power supply spikes and EMI common in those installations.

Ted Perry

The Comnet FDC8NLRM1 is purpose-built for remote switching over fiber in environments where copper twisted-pair either won't survive the EMI or the distance rules it out. I've deployed these in traffic signal control cabinets and railway trackside installations, and the 25 millisecond response time is tight enough that you won't see lag in actuator response — your gate, signal aspect, or HVAC changeover happens when you expect it to.

Technical Highlights:

• 30 VDC, 0.700 Amp Relay Outputs: Enough to drive most 24 VDC solenoids and signal control loads without a second relay stage. If you're feeding a 120 VAC contactor or high-current motor, you'll still need intermediate control logic, but for direct solenoid or PLC input switching, these contacts close the loop cleanly.
• Solid-State Relays with Automatic Resettable Limiters: No moving parts means no contact bounce, no arcing, and no mechanical failure modes in 20-year unattended deployments. Current limiters auto-reset — a short circuit on one relay channel won't take down the entire unit.
• 16 km Multimode Fiber Range on 16 dB Power Budget: Fiber isolation is your EMI shield when you're running fiber through a cabinet full of VFDs, motor starters, or high-voltage switching. The 16 dB budget is moderate — if you're pushing the distance, account for connector loss and fiber age, or spec single-mode if the distance requirement is critical.

Deployment Considerations:

• Point-to-point only — you cannot daisy-chain or split one receiver to multiple transmitters. Confirm your fiber run is truly 1:1 before ordering.
• The failsafe default (relays open on power or link loss) is a feature for safety, but confirm it matches your system's fail-safe logic — if you need a relay to stay closed on link loss, this unit won't do it without external logic.

Deploy this in gate control systems, traffic signal remote actuation, or SCADA field switching where fiber isolation and solid-state reliability outweigh the cost of multimode transceivers. For warehouse automation, I'd skip this unless your facility is too electromagnetically noisy for Ethernet or you're already running dark fiber.