Industrial Contact Closure System Transports 4 Signals Over Fiber​

Industrial Media Converters - 4 Channel Contact Closure SFP

The system provides transmission of four (4) independent input signals over fiber optic cable. Applications include alarm event triggering, building automation, environmental control systems, fire & alarm systems, gate control, traffic signal control equipment, and more.

Fiber optic cable is immune to RF noise, EMI, high voltages, and may extend the signal up to 100km. A complete system requires a Transmitter and Receiver, a 24-48VDC power source, and a compatible SFP transceiver for the fiber interface.

Each unit features a wide operating temperature, redundant power terminals, and a system alarm contact for monitoring the unit for proper operation. LED indicators provide a convenient view of the systems current status. This hardened system can be wall or DIN rail mounted with the included DIN clip and wall mount ears, is made in the USA, and backed by our Limited Lifetime Warranty.

Contact Input – Transmitter Device

The input terminals have the ability to sense 4 independent inputs. The dry contact model makes installation of the unit quick and simple. Wet contact models have the ability to receive an input signal between 5~12VDC or 24~48VDC.

Contact Output – Receiver Device

Each receiver device is paired with a transmitter on the opposite end of the system. The relays will be factory set to Normally Open or Normally Closed and for both these options the switching power is rated at 60Watts (DC or AC).


  • Hardened to operate in -40°F to +158°F (-40°C to +70°C)
  • Compact DIN (T35) rail mount enclosure
  • Can be powered by 24-48VDC (12VDC and 125VDC power options also available)
  • Redundant power inputs with polarity reversal protection, 1.5kV isolation
  • SFP transceiver interface
  • Each output relay is rated for 60 Watts. (Available with NO or NC relays)
  • Inputs can sense a Dry Contact closure
  • Wet Inputs can accept a DC voltage On/Off Signal between 5-12 Volts or 24-48 Volts
  • Each Input is optically isolated, 3.5kV
  • Both sides include alarm contacts for status monitoringConvenient LED status indicators
  • Pluggable terminal blocks
  • Critical, high voltage, remote or un-manned locations operating 24/7/365
  • Limited Lifetime Warranty
  • Made in USA

Fiber Connector Type:
SFP Transceiver

RLH 155Mbps SFP Modules, MSA Compliant SFPs

PWR, STS, LNK, and Inputs 1~4 (TX) or Outputs 1~4 (RX)

Power Input:
24-48VDC (Polarity Insensitive)
Dual redundant power inputs

*12 VDC and 125 VDC powering options also available

Power Consumption:
6 Watts Max

Wire Connectors:
Screw down terminal block, 16-26AWG

Inputs 1-4:
Option (DR) – Dry Contact Sensing
Option (12) – Wet: 5-12VDC
Option (48) – Wet: 24-48VDC

Outputs 1-4:
Option (NC) – Normally Closed
Option (NO) – Normally Open

Output Relay Contacts Maximum Rating:
115AC 1.087A 125VA
12VDC 3.000A 36 Watts
24VDC 2.500A 60 Watts
48VDC 1.250A 60 Watts
130VDC 0.462A 60 Watts
250VDC 0.240A 60 Watts

System Alarm Output:
Normally Open / Closed Relay

Relay Response Time:
5ms typical, 10ms maximum

Surge Protection:
Varistors, Automatic resettable fuses

DC Input Isolation:

Powder coated steel and aluminum alloy

-40°C ~ 70°C (-40°F ~ 158°F)

Operating Humidity:

H 4.93″ x W 1.2″ x D 3.93″ (Not including DIN clip or Connectors)

Standard T35 DIN rail or wall mounted with included ears

General Information
SFP Application System
SFP Application System
Single Fiber System Connection
Single Fiber System Connection


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 SFP

Product configurationTransmitter/ReceiverInputsInput TypeOutputsOutput TypePart numberPrice
1 SFP Slot, 4 Digital Inputs - Dry Contact Sensing, Powering Voltage 24-48 DCTransmitter4 Digital InputsDry Contact SensingN/AN/A4CD-TX-DR-3$445.00
1 SFP Slot, 4 Digital Inputs - 3-15VDC Sinking, Powering Voltage 24-48 DCTransmitter4 Digital Inputs5-15VDCN/AN/A4CD-TX-12-3$445.00
1 SFP Slot, 4 Digital Inputs - 24-48VDC Sinking, Powering Voltage 24-48 DCTransmitter4 Digital Inputs24-48VDCN/AN/A4CD-TX-48-3$445.00
1 SFP Slot, 4 Relay Outputs - Normally Open, Powering Voltage 24-48 DCReceiverN/AN/A4 Relay OutputsNormally Open4CD-RX-NO-3$445.00
1 SFP Slot, 4 Relay Outputs - Normally Closed, Powering Voltage 24-48 DCReceiverN/AN/A4 Relay OutputsNormally Closed4CD-RX-NC-3$445.00
  • A complete system requires one Transmitter and one Receiver
  • SFP Transceivers are sold separately (see list below)
  • For the 125VDC input power option, please note your part number, add -A to the end, and get your quote here
  • For the 12VDC input power option, please note your part number, add -B to the end, and get your quote here

155M SFP Transceiver

Short descriptionModeConnectorDistanceFibersWavelengthPart numberPricehf:att:pa_distancehf:att:pa_fibers
Multimode, LC, 2km/1.2 miles, Dual Fiber, 1310nmMultimodeLC2km/1.2 milesDual Fiber1310nmSFP-155-04-2$55.00
Singlemode, LC, 20km/12.4 miles, Dual Fiber, 1310nmSinglemodeLC20km/12.4 milesDual Fiber1310nmSFP-155-30-2$70.00
Singlemode, LC, 60km/37 miles, Dual Fiber, 1310nmSinglemodeLC60km/37 milesDual Fiber1310nmSFP-155-31-2$80.00
Singlemode, LC, 100km/62 miles, Dual Fiber, 1550nmSinglemodeLC100km/62 milesDual Fiber1550nmSFP-155-34-2$250.00
Singlemode, LC, 20km/12.4 miles, Single Fiber – Side A, Tx1310/Rx1550SinglemodeLC20km/12.4 milesSingle Fiber - Side AT-1310/R-1550SFP-155-20-2$80.00
Singlemode, LC, 20km/12.4 miles, Single Fiber – Side B, Rx1310/Tx1550SinglemodeLC20km/12.4 milesSingle Fiber - Side BR-1310/T-1550SFP-155-21-2$80.00
Singlemode, LC, 60km/37 miles, Single Fiber – Side A, Tx1310/Rx1550SinglemodeLC60km/37 milesSingle Fiber - Side AT-1310/R-1550SFP-155-24-2$90.00
Singlemode, LC, 60km/37 miles, Single Fiber – Side B, Rx1310/Tx1550SinglemodeLC60km/37 milesSingle Fiber - Side BR-1310/T-1550SFP-155-25-2$90.00
  • Single fiber (bi-directional) SFP transceivers must always be paired, side A and side B

*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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