Transport 2 Active Channels of Serial Data Over Fiber

Industrial Media Converters - Serial Data RS-232 & RS-485/422
Serial Data RS-232 & RS-485/422

The RLH Serial Data DIN Fiber Link system transports two active channels of copper serial data over fiber optic cable, allowing for both RS-232 and RS-485/422 to be used at the same time. Fiber optics not only provide long distance communication up to 74 mi. (120km), but also provide immunity to EM/RFI and transient surges. This is ideal for extending serial data communications over long distances, or near large electrical equipment where resistance to EMI is desired.

A comprehensive set of LED’s on the front panel indicate power status, fiber status, RS-232 and RS-485/422 activity. Powering options include our standard 24-48VDC, or high range DC powering of 125VDC. This rugged system also features redundant power inputs with a system alarm contact, and comes standard with DIN clip and wall mount ears.


  • Supports 2 active channels of serial data
  • Simultaneously transmits both RS-232 and RS485/422
  • Convenient LEDs for power, fiber, and serial signals
  • Supports baud rates of 50 bps to 921.6 Kbps baud
  • Extends communication up to 74 mi. (120km)
  • Transparent RS-232 & RS-485/422 extension over fiber
  • Supports 2 & 4 Wire RS-485 operation
  • DC power alarm contact
  • Dual redundant power inputs
  • Rugged design for wide operating temperature is standard
  • Protocols tested: DNP, Modbus, DF1
  • DIN or wall mount with included wall mount accessories
  • Singlemode and multimode models available
  • Limited Lifetime Warranty
  • Made in USA

Transmission Method:
Frequency modulated light via two optical fibers

Multimode: 850nm
Singlemode: 1310nm, 1550nm

Bi-Directional Connector Fiber Type/Distance:
Multimode: (62.5/125µm) 1.24 mi. (2 km), (50/125µm): 1.24 mi./2km
Singlemode: (9/125µm) 12.4mi /20km, 37mi / 60km

Dual Fiber Connector Fiber Type/Distance:
Multimode (62.5/125µm): 1.24 mi./2km, (50/125µm): 1.24mi./2km
Singlemode (9/125µm): up to 74.5mi/120km

Fiber Connector Type:
ST or SC

24~48VDC / 125VDC
Dual Redundant Power Inputs

Serial RS-232 & RS-485/422 Data

H 4.93” x W 1.20” x D 3.93” (not including DIN clip)
Standard T-35 DIN rail mounting or wall mount with included brackets

Operating Temperature:
-25˚C ~ 70˚C (-13˚F ~ 158˚F)

General Information


Point to Point Application
Point to Point Application
2 Channel Point to Point
2 Channel Point to Point


Lead Time: 1 to 2 Weeks*

For product questions, volume pricing and/or delivery outside of the US and Canada, please contact sales.


Serial Data RS-232 & RS-485/422

Product configurationModeConnectorDistanceFibersPart numberPricehf:att:pa_modehf:att:pa_connectorhf:att:pa_distance
Multimode, SC, 2km/1.2 miles, Dual FiberMultimodeSC2km/1.2 milesDual FiberSDD-03-2$380.00
Multimode, ST, 2km/1.25 miles, Dual FiberMultimodeST2km/1.2 milesDual FiberSDD-04-2$380.00
Singlemode, SC, 20km/12.4 miles, Dual FiberSinglemodeSC20km/12.4 milesDual FiberSDD-40-2$480.00
Singlemode, SC, 60km/37 miles, Dual FiberSinglemodeSC60km/37 milesDual FiberSDD-41-2$580.00
Singlemode, SC, 120km/74 miles, Dual FiberSinglemodeSC120km/74 milesDual FiberSDD-45-2$660.00
Singlemode, ST, 20km/12.4 miles, Dual FiberSinglemodeST20km/12.4 milesDual FiberSDD-50-2$480.00
Singlemode, ST, 60km/37 miles, Dual FiberSinglemodeST60km/37 milesDual FiberSDD-51-2$580.00
Singlemode, ST, 120km/74 miles, Dual FiberSinglemodeST120km/74 milesDual FiberSDD-55-2$660.00
Singlemode, SC, 20km/12.4 miles, Single Fiber – Side ASinglemodeSC20km/12.4 milesSingle Fiber – Side ASDD-10-2$520.00
Singlemode, SC, 20km/12.4 miles, Single Fiber – Side BSinglemodeSC20km/12.4 milesSingle Fiber – Side BSDD-11-2$520.00
Singlemode, SC, 60km/37 miles, Single Fiber – Side ASinglemodeSC60km/37 milesSingle Fiber – Side ASDD-14-2$620.00
Singlemode, SC, 60km/37 miles, Single Fiber – Side BSinglemodeSC60km/37 milesSingle Fiber – Side BSDD-15-2$620.00
  • For the 125VDC input power option, please note your part number, add -A to the end, and get your quote here
  • Bi-Directional single fiber models require an A side and B side unit for a complete system

*Lead times are estimates and may vary. You will be contacted within 1 business day to go over the details of your order. If you require a specific date, let us know!
*Days = Business Days

WarningWarning: This product can expose you to chemicals including arsenic, which is known to the State of California to cause cancer. For more information, go to

RLH Industries - Fiber Optic Link
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