Extend Two 4 Wire Data and Contact Closure Signals Over Fiber Optic Cable​​

Industrial Media Converters - 2 Channel 4 Wire Data with E&M and IO System
2 Channel 4 Wire Data with E&M and IO System

This industrial fiber optic media converter is designed to extend two 4 Wire Voice Frequency Signals over fiber optic cable. This system also features bi-directional contact closure for remote relay or alarm status transportation. By extending 4 Wire signals over fiber cable you gain the advantage of sending the signal long distances, up to 120km, as well as gain noise immunity to RF and Electromagnetic Interference.

This system transports two circuits of 4 Wire Data and supports E&M signaling. The devices can be ordered with dual fiber or single fiber transceivers. The 4 wire data supports constant transmission of voice frequency ranging from 300Hz-3,400Hz which is suitable for a wide range of radio and SCADA applications. This RLH Fiber Link system is designed and made in the USA and covered by our Limited Lifetime Warranty.


  • Rugged design, operating temperature range -40°C ~ 70°C
  • Transports voice frequency data 300Hz to 3,400Hz
  • Multiplexes 2 Independent 4 Wire Data Circuits over fiber
  • Supports 600 Ohm audio standard impedance
  • Single fiber and dual fiber transceivers available
  • Extend the signals long distances, up to 120km over fiber
  • Supports E&M signaling
  • Bi-Directional Contact Closure, Transport relay alarms over the same fiber as your 4 Wire circuits
  • Built-in alarm relay to indicate system health
  • Includes both DIN clip and wall mount ears for easy installation
  • System power range options: 24-48VDC or 125 VDC
  • Limited Lifetime Warranty
  • Made in USA

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

Power Consumption:
6 Watts (Maximum)

Fiber Connectors:
ST or SC

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

Analog Bandwidth (Voice Frequency):
300Hz to 3,400Hz

Channel Noise:
< 20dBrnC (15dBrnC typical)

Nominal Impedance:
600 Ohm input and output

Insertion Loss:
0dB +/- 0.5dB each direction

Overload Level:
8dBm into 600 Ohms

E&M Input:
24-48VDC, 3000Vrms optically isolated

E&M Output:
1500VRMS isolation by normally open solid state relay
Closed resistance 35 Ohms (220VAC or 330VDC @ 150mA max.) Open resistance >1M Ohms

Response Time:
Input to output 15-18ms

Contact Closure Input:
Dry contact (100 Ohms maximum loop impedance)

Contact Closure Output:
Relay – Normally Open, Maximum Ratings: 30VDC / 2.0A / 60 Watts

System Alarm Output:
Normally Closed / Normally Open (NCNO) Relay

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

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%
MTBF 175,000 Hrs. (Circuit Board level)

General Information Specialized Drawings Miscellaneous
4 Wire Data with E&M Application
4 Wire Data with E&M Application
RJ-45 Pin Outs
RJ-45 Pin Outs
E&M Circuit
E&M Circuit


Lead Time: 1 to 2 Weeks*

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


2 Channel 4 Wire Data with E&M and I/O System

Product configurationModeConnectorDistanceFibersPart numberPricehf:att:pa_modehf:att:pa_connectorhf:att:pa_distance
Multimode, SC, 2km/1.2 miles, Dual FiberMultimodeSC2km/1.2 milesDual Fiber4D-2EM-IO-03-1$980.00
Multimode, ST, 2km/1.25 miles, Dual FiberMultimodeST2km/1.2 milesDual Fiber4D-2EM-IO-04-1$980.00
Singlemode, SC, 20km/12.4 miles, Dual FiberSinglemodeSC20km/12.4 milesDual Fiber4D-2EM-IO-40-1$1,080.00
Singlemode, SC, 60km/37 miles, Dual FiberSinglemodeSC60km/37 milesDual Fiber4D-2EM-IO-41-1$1,180.00
Singlemode, SC, 120km/74 miles, Dual FiberSinglemodeSC120km/74 milesDual Fiber4D-2EM-IO-45-1$1,370.00
Singlemode, ST, 20km/12.4 miles, Dual FiberSinglemodeST20km/12.4 milesDual Fiber4D-2EM-IO-50-1$1,080.00
Singlemode, ST, 60km/37 miles, Dual FiberSinglemodeST60km/37 milesDual Fiber4D-2EM-IO-51-1$1,180.00
Singlemode, ST, 120km/74 miles, Dual FiberSinglemodeST120km/74 milesDual Fiber4D-2EM-IO-55-1$1,370.00
Singlemode, SC, 20km/12.4 miles, Single Fiber - Side ASinglemodeSC20km/12.4 milesSingle Fiber - Side A4D-2EM-IO-10-1$1,120.00
Singlemode, SC, 20km/12.4 miles, Single Fiber - Side BSinglemodeSC20km/12.4 milesSingle Fiber - Side B4D-2EM-IO-11-1$1,120.00
Singlemode, SC, 60km/37 miles, Single Fiber - Side ASinglemodeSC60km/37 milesSingle Fiber - Side A4D-2EM-IO-14-1$1,260.00
Singlemode, SC, 60km/37 miles, Single Fiber - Side BSinglemodeSC60km/37 milesSingle Fiber - Side B4D-2EM-IO-15-1$1,260.00
  • For the 125VDC input power option, please note your part number, add -A to the end, and get your quote here
  • A complete system requires 2 units
  • 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 www.P65Warnings.ca.gov.

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