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

FBR-Serial-2 (SM/ST)

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The FBR-Serial-2 (SM / ST) is a single-mode (SM), rugged, industrial-grade, multi-function RS232 / RS422 / RS485 to fiber optic converter that supports asynchronous RS232 / RS422 / RS485 communications through point-to-point fiber optic links. The FBR-Serial-2 works in pair (point to point) and it runs on light-speed fiber backbone which inherently resistant to radio and electrical interference, such as EMI / RFI, lightning, transient surges, and ground loops. This industrial Serial-to-Fiber-Optic converter supports multi-drop RS485 / RS422 networks and can be used to communicate with up to 128 nodes of RS485 / RS422 devices. It operates within a temperature range of -40ºF to 185ºF (-40ºC to 85ºC), and features 600W surge protection, 15kV ESD static protection, and data format auto-sensing and self-adjusting. No DIP switch, jumper settings or software drivers are required for this device. The FBR-Serial-2 (SM / ST) fiber optic converter can extend the RS232 / RS422 / RS485 distance to 25 miles (40 km). Standards can be mixed and matched, so RS-232 devices can be connected to RS485 / RS422 devices, or RS485 (2-wire) devices can be connected to RS422 (4-wire) devices without using a converter and isolator. The FBR-Serial-2 (SM / ST) comes with ST connectors for fiber optic links, and, thanks to the professional and unique casing design, the product can be mounted directly on a wall, panel, rack or DIN Rail, without a need of using any unsecured DIN-Rail or wall-mount brackets. A separate external power supply is included in the package.

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 fiber optic converter.
  • Transmits serial data (RS232, RS485 or RS422) over long distances through fiber links (single-mode: 25 miles or 40 km).
  • Standards can be mixed and matched (same data type; one side RS232 and the other side RS485 or RS422; one side RS485 and the other side RS422, etc.).
  • Industrial grade enclosed in a rugged, rustless ABS housing.
  • Supports serial data rates from 300 to 115,200bps.
  • Supports multi-drop RS485 / RS422 networks (up to 128 nodes).
  • Direct DIN-Rail (Rack) or Wall / Panel mounting (stackable).
  • Plug and play (hot-pluggable; data format auto-sensing and self-adjusting).
  • Data direction auto-turnaround.
  • No software drivers, DIP switch or jumper settings required.
  • Single mode with ST connectors.
  • Supports a wide range of fiber optic cables.
  • 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-CE-100005; SG-FCC-100002).
  • 5-year manufacturer's warranty.


Part Number: FBR-Serial-2
Compatibility: EIA/TIA RS-232C, RS-485, and RS-422 standards
Power Source: 9 to 30V DC (External AC to DC power adapter included)
External AC/DC Power Adapter: 9V DC / 500mA (Input: 100~240V AC 50/60Hz, US type A plug)
Consumption: Less than 100mA
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: 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);
Multi-mode: 3 miles (5km)
Connectors (Serial Port/Power): Serial port / power: 10-way terminal block
Connectors (Fiber Links): 2x ST Connector; 2x SC Connector; or 2x FC Connector
Surge protection: 600W
Electro-Static Discharge (ESD): Up to 15kV
Dimensions (H x W x D): 5.0 x 3.6 x 0.9 in (127 x 73 x 33 mm)
Weight: 4.6 oz (130 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

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