Transport 2 Active Channels of Serial Data Over Fiber​

Fiber Optic Isolation Systems - RS-232 & 485/422
RS-232 & 485/422

The Serial Data Fiber Link Card 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 EMI/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.

The system supports serial data rates from 50 bps to 921.6Kbps, and has an auto-sensing feature that eliminates the need to manually set serial data rates. The included Pull High / Pull Low rotary dials allows for fast and easy biasing adjustment. Each Fiber Link Card requires 24-48VDC and has a comprehensive set of LEDs on the front panel that indicate power status, fiber status, and activity for RS-232 and RS-485/422 channels.


  • Rugged design for wide operating temperature of -25°C to +70°C
  • 24-48VDC powering required
  • Available with ST or SC connectors for single or multimode fiber
  • ST and SC singlemode and multimode fiber units available
  • Supports baud rates of 50 bps to 921.6 Kbps baud
  • Supports 2 & 4 Wire RS-485 operation
  • Critical, high voltage, remote or un-manned locations operating 24/7/365
  • On/Off Termination Resistor Dip Switch for RS-485/422
  • Protocols tested: DNP, Modbus, DF1, and Profibus
  • Limited Lifetime Warranty
  • Made in USA

Transmission Method:
Frequency modulated light via two optical fibers

Multimode: 1310nm
Singlemode: 1310nm

Fiber Type/Distance:
Multimode (62.5/125µm, 50/125µm): 1.2 mi./2km
Singlemode (9/125µm): 12.4 mi./20km, 37 mi./60km, 74 mi./120km

Fiber Connector Type:
ST or SC

24~48VDC nominal, 150mA @ 24VDC or 3.6 Watt

Serial RS-232 & RS-485/422 Data

H 3.93” x W 1.24” x D 6.94”
(Standard RLH Fiber Link Card Form Factor)

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

General Information Specialized Drawings Miscellaneous
RS232 & 485/422 Single Channel Application
RS232 & 485/422 Single Channel Application
RS232 & 485/422 2 Channel Application
RS232 & 485/422 2 Channel Application


Lead Time: 1 to 2 Weeks*

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


RS-232 & 485/422

Product configurationModeConnectorDistanceFibersPart numberPricehf:att:pa_modehf:att:pa_connectorhf:att:pa_distance
Multimode, ST, 2km/1.25 miles, Dual FiberMultimodeST2km/1.2 milesDual FiberSD4-04-2$830.00
Singlemode, SC, 20km/12.4 miles, Dual FiberSinglemodeSC20km/12.4 milesDual FiberSD4-40-2$930.00
Singlemode, SC, 60km/37 miles, Dual FiberSinglemodeSC60km/37 milesDual FiberSD4-41-2$1,030.00
Singlemode, SC, 120km/74 miles, Dual FiberSinglemodeSC120km/74 milesDual FiberSD4-45-2$1,220.00
Singlemode, ST, 20km/12.4 miles, Dual FiberSinglemodeST20km/12.4 milesDual FiberSD4-50-2$930.00
Singlemode, ST, 60km/37 miles, Dual FiberSinglemodeST60km/37 milesDual FiberSD4-51-2$1,030.00
Singlemode, ST, 120km/74 miles, Dual FiberSinglemodeST120km/74 milesDual FiberSD4-55-2$1,220.00
Singlemode, SC, 20km/12.4 miles, Single Fiber - Side ASinglemodeSC20km/12.4 milesSingle Fiber - Side ASD4-10-2$970.00
Singlemode, SC, 20km/12.4 miles, Single Fiber - Side BSinglemodeSC20km/12.4 milesSingle Fiber - Side BSD4-11-2$970.00
Singlemode, SC, 60km/37 miles, Single Fiber - Side ASinglemodeSC60km/37 milesSingle Fiber - Side ASD4-14-2$1,110.00
Singlemode, SC, 60km/37 miles, Single Fiber - Side BSinglemodeSC60km/37 milesSingle Fiber - Side BSD4-15-2$1,110.00
  • Plug and play compatible with -1 model RS-232 & 422/485 Serial Data Fiber Link Card systems
  • Bidirectional single fiber models require an A side and B side card for a complete system
  • This card is designed to be installed into a Card Housing

*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

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