Rugged, Compact, and Reliable 9-PIN RS-232 over Fiber Solution

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Fiber Optic

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  • Rugged design - Extreme operating temperature rating
  • 9-PIN RS-232 Signal - DCD, RXD, TXD, DTR, GND, DSR, RTS, CTS, RI
  • Selectable DTE/DCE switch
  • Each PIN is optically isolated
  • Optional Breakout Cable for 3 channels of RS-232 serial data
  • Convenient LEDs for power, fiber, and serial signals
  • Non-removable transceiver for ease of ordering and maximum operating reliability
  • Available with ST or SC connectors
  • Available in Single or Multi-mode fiber, supports fiber distances up to 74mi /120km
  • Dual and single (Bi-directional) fiber models available
  • LED's for power, fiber, and serial signal activity
  • System power range options: 24-48VDC or 125 VDC
  • Redundant Power Inputs
  • Built-in surge, over current, and polarity reversal protection
  • DIN rail or wall mount (Includes wall mount ears)
  • Limited Lifetime Warranty

  • Made in USA

This Industrial Serial Data DIN Fiber Link system transports a full 9-PIN RS-232 copper signal over fiber optic cable. This is an ideal solution for extending serial data communications over long distances or near large electrical equipment. Fiber optics provide long distance communication up to 74 mi. (120km) and immunity to EMI/RFI and potential transient surges which can cause noise or damage equipment.

The system supports asynchronous serial data rates from 50 bps to 1Mbit/s and has an auto-sensing feature that eliminates the need to manually set serial data rates. A comprehensive set of LEDs on the front panel indicate power status, fiber status, and serial data activity. Powering options include standard 24-48VDC or high range DC powering of 125VDC. This rugged system is designed to operate over a wide operating temperature -40 to +70°C and features are dual redundant power inputs, and a system alarm relay for maximum uptime and reliability. Included is a DIN clip and wall mount ears for easy installation into to a wide range of environments.


For a comprehensive review of the product specs, please see the Data Sheet, or feel free to contact us with any questions.

Powering Voltage:
Standard Model - 24-48VDC
-A Model - 125VDC

Power Consumption:
3.6 Watts (Maximum)

Fiber Connectors:
ST or SC

Fiber Type:
Singlemode up to 120km
Multimode up to 2km, supports 62.5μm and 50μm


DB-9 Port:

RS-232 Signal Isolation:
Optical Isolation 3000 Vrms

DIP Switches:
DCE / DTE - Specifies the DB-9 Ports Operational Mode

FIBER - Fiber Connection OK
TX - RS-232 Copper Transmit
RX - RS-232 Copper Receive

Surge Protection:
Varistors & Automatic resettable fuses
DC Input Isolation 1.5kV
Voltage Reversal Protection

Powder coated steel and aluminum alloy
Physical Dimensions H 4.93” x W 1.20” x D 3.93” (125mm x 31mm x 100mm)

Mounting Style:
Standard DIN rail (T-35)
Wall mount (with included ears)

Temperature -40°F to +158°F (-40°C to +70°C)
Humidity 95%

Limited Lifetime

DTE Device (PC) To DCE Device (Modem)

Industrial RS-232 Serial Data Fiber Converter

Industrial RS-232 Serial Data Fiber Converter

DCE Device To DCE Device

Industrial RS-232 Serial Data Fiber Converter

Breakout Cable Application Diagram

Industrial RS-232 Serial Data Fiber Converter

Straight Through 9 Pin Serial Cable

Industrial RS-232 Serial Data Fiber Converter

Null (Crossover) 9 Pin Serial Cable


Download the RLH Data Sheet

Download the RLH User Guide


RS-232 DIN Fiber Link Devices

OpticsSideDistanceWavelengthFiberProduct Number
Dual Fiber
Multimode SC
-2 km/1.2 mi.1310nm50/62.5 μmSED-03-2
Dual Fiber
Multimode ST
-2 km/1.2 mi.1310nm50/62.5 μmSED-04-2
Single Fiber
Singlemode SC
A20km / 12.4 mi.Tx 1310nm
Rx 1550nm
B20km / 12.4 mi.Tx 1550nm
Rx 1310nm
A60km / 37 mi.Tx 1310nm
Rx 1550nm
B60km / 37 mi.Tx 1550nm
Rx 1310nm
Dual Fiber
Singlemode SC
-20km / 12.4 mi.1310nm8~9μmSED-40-2
-60km / 37 mi.1310nm8~9μmSED-41-2
-120km / 74 mi.1550nm8~9μmSED-45-2
Dual Fiber
Singlemode ST
-20km / 12.4 mi.1310nm8~9μmSED-50-2
-60km / 37 mi.1310nm8~9μmSED-51-2
-120km / 74 mi.1550nm8~9μmSED-55-2
  • Add -A to the end of the part number for 125VDC input power option
  • Bidirectional single fiber models require an A Side and B Side unit for a complete system

DB-9 Serial Cables

DescriptionLengthConnector EndsProduct Number
Straight Through Cable
(DB-9 Serial)
6 FeetMale / MaleDB9-S-MM-06FT
Male / FemaleDB9-S-MF-06FT
Female / FemaleDB9-S-FF-06FT
Null / Crossover Cable
(DB-9 Serial)
6 FeetMale / FemaleDB9-X-MF-06FT
Female / FemaleDB9-X-FF-06FT
DB-9 Breakout Cable4 FeetMale / 3 FemaleDB9-BREAKOUT-MF-04FT
DB-9 Gender ChangerN/AMale / MaleDB9-GENDER-MM

Please submit a quote request or contact your RLH sales representative for pricing and delivery information.