RS232 / RS485 / RS422 to Multi-Drop Fiber Optic Converter (Industrial / SingleMode / ST)

FBR(M)-Serial-2 (SM/ST)

  •    In Stock

- Instant Volume Discounts
- FREE Worldwide Shipping / Optional Express Shipping
- Require a Custom Solution? Contact us now


The FBR(M)-Serial-2 (SM / ST) is an advanced, single-mode (SM), rugged, industrial-grade RS232 / RS422 / RS485 to fiber optic converter that supports asynchronous RS232 / RS422 / RS485 communications through multi-drop fiber optic links. The FBR(M)-Serial-2 supports up to 255 fiber nodes, and each fiber node can extend the RS232 / RS422 / RS485's distance to 25 miles (40km) for single-mode converters and cables. Depending on the site situation, the FBR(M)-Serial-2 can be configured as a daisy-chain or a self-healing / redundant ring fiber network. When configured as a ring fiber network, the built-in self-healing feature allows the data to be transmitted clockwise or counterclockwise; therefore, failure of any individual converter will not affect other devices located on the same fiber ring, making the entire data network more robust and reliable. The unit also features redundant power supplies and power alarm outputs for uninterrupted system performance and easy maintenance. The FBR(M)-Serial-2 runs on a light-speed fiber backbone inherently resistant to radio and electrical interference, such as EMI / RFI, lightning, transient surges and ground loops, and it overcomes the limitations of conventional point-to-point fiber network and dramatically expands the serial data network in terms of distance, flexibility, and reliability. The FBR(M)-Serial-2 (SM / ST) comes with ST connectors for fiber optic links, and it accepts a wide range of industrial DC input (from 18V to 36VDC). The product can be mounted directly on a DIN Rail, without a need of using any unsecured DIN-Rail brackets or adapters.

CommFront's products quality is ensured by our ISO-9001 quality control system (Cert No. SG12/04213, strictly certified by SGS), and we back our high-quality products with a 5-year replacement warranty and a 30-day risk-free money-back guarantee.


  • Rugged industrial-grade RS232 / RS485 / RS422 to multi-drop fiber optic converter.
  • Daisy-chain or self-healing / redundant ring fiber network configurations.
  • Extends serial data network uninterruptedly over extremely large areas.
  • Designed for harsh industrial environments.
  • Direct DIN-Rail mounting without using any unsecured brackets or adapters.
  • Single mode with ST fiber optic connectors.
  • Supports up to 255 fiber nodes.
  • Supports up to 128 nodes of RS-485 / 422 devices per fiber node.
  • Fiber link distance (single-mode): 25 miles (40km) per fiber node.
  • Full redundant power supply and fiber network.
  • No software drivers required.
  • Power loss alarm relay output.
  • Built-in selectable 120-Ohm end-of-line terminator for RS485/RS422 busses.
  • Operating temperature: -40ºF to 185ºF (-40ºC to 85ºC).
  • Built-in 600W surge protection, 15kV static protection and circuit protection.
  • Surface Mount Technology manufactured to RoHS and ISO-9001 standards.
  • Safety: Strictly certified by TUV (Cert No. SG-FCC-140002; E8N140387592001).
  • 5-year manufacturer's warranty.


Part Number: FBR(M)-Serial-2
Compatibility: EIA/TIA RS-232C, RS-485, and RS-422 standards
Power Source: 18 to 36VDC (with opto-isolation)
Consumption: Less than 5W
Wavelength: 1310nm
Output Power (Fiber): Single-Mode: -8dBm(Min); -7dBm(Typical); -5dBm(Max)
Multi-Mode: -15dBm(Min); -10dBm(Typical); -8dBm(Max)
Sensitivity (Fiber): Single-Mode: -35dBm; Multi-Mode: -34dBm
FO Connector Type: PC/UPC
Usable Fiber Optic Cables: Single-mode: 8.3 / 125, 8.7 / 125, 9 / 125, 10 / 125µm
Multi-mode: 50 / 125, 62.5 / 125µm (supports OM1OM2, OM3, and OM4)
Maximum Number of Nodes: Fiber: 255 nodes; RS485 / RS422: 128 nodes
Serial Data Rates: 300 to 115,200bps (auto-sensing and self-adjusting)
Distance (Serial Port): RS232: 16ft (5m); RS485 / RS422: 4000ft (1.2km)
Distance (Fiber Lines): Single-mode: 25 miles (40km) per fiber node;
Multi-mode: 3 miles (5km) per fiber node
Connectors (Serial Port): 7-way terminal block (1x RS-232, 1x RS-485, 1x RS-422)
Connectors (Fiber Links): 4x ST Connector; 4x SC Connector; or 4x FC Connectors
Connectors (Power): 6-way terminal block (1x V1 power, 1x V2 power, 1x Alarm)
Surge protection: 600W
Electro-Static Discharge (ESD): Up to 15kV
Dimensions (H x W x D): 5.7 x 3.8 x 1.3 in (144 x 97 x 33 mm) - excluding connectors
Weight: 1 lb (460 g)
Operating Temperature: -40ºF to 185ºF (-40ºC to 85ºC)
Operating Humidity: Up to 90% RH (no condensation)





CommFront products are strictly certified by SGS and/or TUV - the Nationally Recognized Testing Laboratories [NRTLs] in North America (approved by OSHA) and the Notified Bodies in the European Union. Learn More




CommFront products are designed and manufactured to ISO 9001 standards. Our quality control system is strictly certified by SGS (Cert No. SG12/04213). Learn More




CommFront products have been proven to be reliable. We back our high-quality products with a 5-year replacement warranty and a 30-day risk-free money-back guarantee. Learn More

We Also Recommend

FBR(M)-Serial-2 (MM/ST)

RS232 / RS485 / RS422 to Multi-Drop Fiber Optic Converter (Industrial / MultiMode / ST)


FBR(M)-Serial-2 (MM/SC)

RS232 / RS485 / RS422 to Multi-Drop Fiber Optic Converter (Industrial / MultiMode / SC)


FBR(M)-Serial-2 (SM/SC)

RS232 / RS485 / RS422 to Multi-Drop Fiber Optic Converter (Industrial / SingleMode / SC)