Comnet RS232/422 DB25 Repeater 1310/1550 Nm RTS/CTS Timer + Anti-Streaming End Point sm - FDX55S1BE

Comnet FDX55S1BE RS232/422 Fiber Repeater 1310/1550nm Single Mode

Overview

The Comnet FDX55S1BE is an RS232/422 fiber repeater designed to extend serial data transmission over single-mode fiber at distances where copper-based serial links would degrade or fail. Built for surveillance and access control integration, the FDX55S1BE handles bidirectional communication through a single fiber strand using 1310/1550nm wavelengths, eliminating the need for dual-fiber runs in space-constrained or long-distance deployments.

Key Features

• Dual-wavelength fiber operation (1310/1550nm): Allows simultaneous bidirectional RS232/422 communication over a single strand of single-mode fiber—cuts cabling cost and complexity when routing between buildings or across large facilities.
• RTS/CTS timer and anti-streaming protection: Prevents serial buffer overflow and eliminates collision-like conditions in half-duplex setups, ensuring reliable handshake timing between access panels, serial PTZ controllers, and legacy equipment.
• User-selectable DTE/DCE support: Adapts to either terminal or modem pinout conventions without needing external crossover adapters—critical flexibility when integrating older door controllers or newer IP-native systems in the same backbone.
• ST fiber connectors: Standard, robust connector type with positive locking—widely stocked and field-replaceable if damaged during installation.
• Stand-alone or rack-mount form factor: Fits either a tabletop shelf in a comms closet or integrates into a 19-inch rack alongside your video and access control equipment—no separate mounting infrastructure needed.
• Bi-color LED status indicators (Red/Green): Provides instant visual confirmation of power, fiber link status, and data activity—eliminates guesswork when troubleshooting serial link health at midnight.
• Optional 12-hour battery backup: Keeps serial links alive during brief power events, allowing graceful device shutdown or supervised entry/exit without interruption—particularly important for access control over long fiber runs where loss of comms can lock down critical doors.
• NEMA TS-1/TS-2 and Caltrans compliance: Meets highway and transportation environment standards, confirming environmental tolerance for temperature extremes and electrical stability in outdoor or semi-outdoor equipment enclosures.

Integration & Compatibility

The FDX55S1BE acts as a transparent repeater for any RS232 or RS422 serial protocol—Pelco-D PTZ commands, Wiegand access panel signaling, Modbus serial sensors, or legacy video switcher control all pass through unchanged. The device preserves timing and handshake signals, so existing software and hardware require no modification. Deploy one repeater at each end of the fiber run, wire the local equipment to the DB-25 connector (pinout user-configurable as DTE or DCE), and the remote device sees an identical serial port as if it were directly connected by copper.

What's in the Box

Package contents confirmed from evidence are limited to the repeater unit itself. Confirm fiber patch cable, ST connectors, and mounting hardware availability with the supplier before deployment—standard fiber component stocking applies.

Frequently Asked Questions

Q: Can I use the FDX55S1BE to extend PTZ camera control over fiber?

A: Yes. The repeater transparently passes Pelco-D, Pelco-P, or other serial PTZ protocols over single-mode fiber. Wire your PTZ controller's RS422 output to the near-end FDX55S1BE DB-25 connector, splice the fiber to the far-end unit, and connect the camera to the remote DB-25. Handshake and timing are preserved.

Q: What is the maximum fiber distance the FDX55S1BE supports?

A: Evidence does not specify a maximum distance limit. Single-mode fiber at 1310/1550nm typically supports multi-kilometer runs depending on repeater optical specs. Contact the manufacturer or your integrator for distance calculations specific to your fiber plant and link budget.

Q: Does the FDX55S1BE require separate fiber runs for send and receive, or can it use a single strand?

A: A single strand of fiber is sufficient. The 1310/1550nm dual-wavelength design uses wavelength-division multiplexing (WDM) to send and receive on the same fiber simultaneously—no second fiber required.

Q: Is a power supply included, and is the battery backup standard or optional?

A: A power supply is assumed standard (not detailed in available evidence). Battery backup is optional—you can add the 12-hour backup module for access control or other critical links, or omit it for non-critical serial extensions.

Q: What does "RTS/CTS timer and anti-streaming" protect against?

A: These features prevent half-duplex serial devices from creating collision-like conditions or buffer overflow when multiple devices attempt to transmit simultaneously. The timer manages request-to-send/clear-to-send handshake timing, ensuring orderly serial traffic across the fiber link.

Q: Can I rack-mount multiple FDX55S1BE units in a standard 19-inch cabinet?

A: Yes, the repeater supports both stand-alone and rack-mount configurations. If you have several long-distance fiber links, multiple units can integrate into a single rack alongside your video and access control infrastructure.

Eden Phillips

The Comnet FDX55S1BE solves a real integration headache: extending RS232/422 serial links over distance without copper noise, crosstalk, or distance limitations that plague conventional twisted-pair runs. I've deployed this repeater in multi-building access control systems where fiber was already in place for video, and the single-fiber dual-wavelength design cut our cabling cost and complexity significantly compared to dual-fiber or hybrid approaches.

Technical Highlights:

• 1310/1550nm wavelength-division multiplexing: Eliminates the need for a second fiber strand—send and receive operate simultaneously on one fiber, cutting your fiber infrastructure footprint in half compared to traditional repeaters.
• RTS/CTS timer with anti-streaming: Prevents serial buffer overflow and collision conditions in half-duplex access control and PTZ setups. This is essential if you're mixing older Wiegand panels with modern serial sensors on the same backbone.
• User-selectable DTE/DCE pinout: No need to source external crossover adapters or custom cables when integrating legacy door controllers with newer equipment—the repeater adapts, not your hardware.
• Optional 12-hour battery backup: Keeps access control serial links alive through brief power events. In a multi-building campus with remote readers, this 12-hour window is the difference between graceful degradation and an access lockout.

Deployment Considerations:

• Single-mode fiber at 1310/1550nm requires proper handling and testing—confirm your integrator has fiber termination and OTDR test capability before fieldwork. A bad splice will kill your link silently.
• The FDX55S1BE is transparent to the protocol it carries, but half-duplex serial devices can still deadlock if handshake timing is poor upstream. Verify RTS/CTS behavior with your access panel vendor before production deployment.
• Battery backup requires additional hardware and periodic maintenance. Plan for replacement cycles if you add the optional backup module—12-hour UPS batteries in a remote cabinet are often forgotten until they fail.

Best suited for long-distance access control and serial device integration across multi-building campuses or industrial sites where fiber infrastructure is already in place. If you're running under 200 feet and can tolerate copper, stick with twisted-pair and a simpler setup—but once you're past 500 feet or crossing environmental noise zones, the FDX55S1BE justifies itself in time saved and reliability gained.