Transmit 4 Contact Closures Over a Single Fiber​

Fiber Optic Isolation Systems - 4 Channel Contact Closure

The RLH 4 Channel Contact Closure fiber link system provides a transmission of up to four independent contact closure signals over one optical fiber. The system comprises two 4 channel cards, a transmitter card and a receiver card.

The transmitter card provides the electrical-to-optical interface between dry contact closure relay input and a fiber strand.

The receiver card is locally powered by a 24-56VDC source and provides LED indicators to display relay conditions, power, and fiber carrier receive.

This fiber link card is designed to be installed into any of the RLH Fiber Link Card Housings, and occupies a single card slot.


  • Available with ST or SC Connectors
  • Convenient LED status indicators
  • Single and Multimode fiber models available
  • RX side includes alarm contact for status monitoring
  • Alarm contact may be set to Normally Open or Normally Closed
  • DC power is not polarity sensitive, simplifying wiring duties
  • Environmentally rugged with wide operating range: -40˚F to +158˚F (-40˚C to +70˚C)
  • Single slot RLH Fiber Link Card form factor allows up to 12 cards in a 12 card housing, or multiple housings for larger installations
  • Limited Lifetime Warranty
  • Made in USA

Transmission Method:
Frequency modulated light via two optical fibers

Multimode: 850nm
Singlemode: 1310nm

Fiber Type/Distance:
Multimode (62.5/125µm, 50/125µm): 6dB / 1.2 miles (2km)
Singlemode (9/125µm): 8dB / 9 miles (15km)
Singlemode Long Haul: 24dB* / 29 mi. (48 km), min. required loss *-8dB

*Note: Distances equated using industry standard fiber and connector attenuation of 3dB/km. Fiber condition, splices and connectors may affect actual range.

Fiber Connector Type:
ST or SC

7in. x 4in. x 1.24in. (177.8mm x 101.6mm x 31.5mm)
(Standard RLH Fiber Link Card Form Factor)

Operating Temperature:
-40˚F to +158˚F (-40˚C to +70˚C)

Operating Humidity:
95% non-condensing

4 Channel Contact Closure Application
4 Channel Contact Closure Application


Lead Time: 1 to 2 Weeks*

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


4 Channel Contact Closure

Product configurationCard TypeModeConnectorDistanceFibersPart numberPricehf:att:pa_card-typehf:att:pa_modehf:att:pa_connector
Transmitter Card, Multimode, ST, 2km/1.2 miles, Single FiberTransmitter CardMultimodeST2km/1.2 milesSingle Fiber4C4-M2STT-02$890.00
Receiver Card, Multimode, ST, 2km/1.2 miles, Single FiberReceiver CardMultimodeST2km/1.2 milesSingle Fiber4C4-M2STR-02$890.00
Transmitter Card, Singlemode, ST, 15km/9 miles, Single FiberTransmitter CardSinglemodeST15km/9 milesSingle Fiber4C4-S3STT-02$990.00
Transmitter Card, Singlemode, ST, 48km/29 miles, Single FiberTransmitter CardSinglemodeST48km/29 milesSingle Fiber4C4-S4STT-02$1,200.00
Receiver Card, Singlemode, ST, 15km/9 miles & 48km/29 miles, Single FiberReceiver CardSinglemodeST15km/9 miles & 48km/29 milesSingle Fiber4C4-S3STR-02$990.00
Transmitter Card, Singlemode, SC, 15km/9 miles, Single FiberTransmitter CardSinglemodeSC15km/9 milesSingle Fiber4C4-S3SCT-02$990.00
Transmitter Card, Singlemode, SC, 48km/29 miles, Single FiberTransmitter CardSinglemodeSC48km/29 milesSingle Fiber4C4-S4SCT-02$1,200.00
Receiver Card, Singlemode, SC, 15km/9 miles & 48km/29 miles, Single FiberReceiver CardSinglemodeSC15km/9 miles & 48km/29 milesSingle Fiber4C4-S3SCR-02$1,110.00
  • A complete system requires one Transmitter and one Receiver

*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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