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2-Wire Audio Transceiver With Serial Data And Control (E&M 2-wire)

Model #: FOI-7282



The FiberPlex Technologies FOI-7282 is an innovative fiber conversion unit which allows for the creation of point-to-point or daisy chained connections utilizing your current inventory of 2-wire party-line intercom systems such as RTS and ClearCom. The unit converts 2-wire duplex analog audio to fiber for long or short haul transport. In addition to the audio, a multi-format serial data connection and a bidirectional pair of contact closures are included. The combination of audio and signaling also provides a seamless solution for 2-wire E&M applications. 

As part of the FiberPlex 7200 series of converters, the FOI-7282 is optically compatible with other units in the series. For example, the FOI-7282 can be paired with a FOI-7280 to create a 2-wire to 4-wire conversion over fiber. 

What’s the difference between the FOI and the TD versions?

Functionally, the FOI-7282 and TD-7282 are identical. The only differences are the packaging and power supply. The FOI-7282 is part of the FOI line of products designed for ruggedized military applications while the TD-7282 is housed in the commercial ‘Throw Down’ packaging.
  FOI-7282 TD-7282
Standalone Power Requires a PSQ-4909 AC supply or PSQ-4920 DC supply Power Supply included
Power Connection High Reliability Lemo™ connector Both circular DC connector and 3-postion Phoenix™ quick connect
Chassis Mounting Uses the RMC series chassis for up to 9 units in 2U or 8 units with redundant power supply 6 units in a 1U with the optional TDR-01-AC
Case Mil-style sealed steel can enclosure Durable anodized brushed aluminum


Various advanced routing and networking options are available via DIP switch setting. These include the following:

Point to point mode

Point to Point

Basic configuration. Audio inputs one unit map directly to audio outputs on the other unit. Serial data and contact closures are a direct connection.  

Broadcast Mode

Broadcast Mode

One unit is configured as the master, which sets the clock and sampling rate. Analog and serial inputs to the master are sent to all the slaves, which output the data on their respective ports. No communication is sent from the slaves to any other units.   

Intercom / Loop mode

Loop Mode

One unit is configured as the master, which sets the clock and sampling rate. It polls the loop, with each unit in the loop adding its own input to the aggregated sample, gated by its push to talk, if enabled. When the sample returns back to the master, it then sends out that aggregated sample as the output for all units in the loop. All units forward the aggregated output around the loop until it returns to the master, which discards it. Serial data from the master is replicated on all slaves, and serial data from the slaves is aggregated to output on the master. 

Typical Applications


E&M Type IV

Intercom / Loop



Audio Interface:

  • Supports 2-Wire Full and Half Duplex Audio I/O
  • High Quality 24-bit audio
  • Supports both RTS™ and ClearCom™ signaling
  • Supports Ultrasonic Signaling

Serial Interface:

  • RS-232, RS-422, RS-485 (2/4 wire)
  • Data Rates from 0 to 1 Mbps

Contact Closures:

  • ‘Form C’ Contacts
  • Supports Push to Talk

Advanced Routing:

  • Point to Point
  • Broadcast Mode
  • Intercom/Loop
  • Multichannel Add/Drop


  • TD includes power adapter as well as a 3-position Phoenix™


  • Party-Line Intercom
  • 2-Wire to 4-Wire Conversion
  • Push To Talk
  • E&M
  Min Typ Max unit
  Min Typ Max unit
RS-422 / RS-485 Output Levels into 100Ω Load - ±2 - VDC
Input Levels -7 - +7 VDC
Input Threshold ±0.2 - - VDC
Data Rate 0 - 1 Mbps
Input Termination - 150 -
RS-232 Output Levels, 3KΩ Termination ±5 ±5.4 - VDC
Input Levels -15 - +15 VDC
Input Threshold ±3 - - VDC
Data Rate 0 - 1 Mbps
Input Termination 3 - 2.3 K Ω
  Min Typ Max unit
Shorting Actuation Voltage Threshold - 0 2.5 VDC
Load - 0 1
Negative Voltage Actuation Voltage Threshold -48 - -6 VDC
Load 2 - 25 mA
Relay Output On Resistance - 10 15 Ω
Off Resistance NO contacts 0.35 - 5000
Off Resistance NC Contacts 0.1 - 1.4
Voltage Limit 0 - 200 VDC
Current Limit 0 - 200 mA
  Min Typ Max unit
Environmental Storage Temperature (°C) -40 - 85 °C
Operating Temperature (°C) 0 - 50 °C
Power Requirement Voltage Range 7 9 24 VDC
Supply Current, no SFPs - 600 - mA
Phoenix™ Mating Plug 6 pos Audio/Serial/Control(PN 1778874) Wire Accepted 20 - 26 AWG
Nominal Voltage - - 160 V
Nominal Current - - 6 A
Phoenix™ Mating Plug 3 pos Power (TD Only)(PN  1827716) Wire Accepted 14 - 28 AWG
Nominal Voltage - - 300 V
Nominal Current - - 8 A
Power Adapter Connection FOI-7282 LEMO™
TD-7282 Standard 5.5 x 2.1 mm DC barrel, center positive
External SFP Interface Min Typ Max unit
Data Rate - 346 - Mbps
Recommended Jitter - 40 - Psec
Operating Voltage - 3.3   VDC
Maximum Current - - 500 mA
Optical Modules SFP MSA (SFF-8431, SFF-8432, SFF-8433) compliant slot, data rate 266 – 1.25 Gbps
Case Dimensions Length Width Height Weight
FOI-7282    (Size 4) 4.5 in (114 mm) 1.453 in (37 mm) 2.56 in (65 mm) 2 lb (0.9 kg)
TD-7282 4.5 in (114 mm) 2.75 in (70 mm) 1.66 in (42 mm) 0.4 lb (0.2 kg)
PDF Document Datasheet
PDF Document User Manual
Standalone Operation  
PSQ-4909  Standalone AC Power Supply
PSQ-4920 Standalone DC Power Supply
WMA-3002 Wall Mount Adapter
WMA-2001 Wall Mount Adapter with ST Optical Patch
Chassis Mounting  
RMC-2101 2U, 19" Rack Mount Chassis. Holds up to 9 FOI Modules
CMA-2001 Chassis Mount Adapter for RMC-2101 Chassis. (1) per FOI Module required
PSM-2010 Spare Power Supply for RMC-2101
RP2 16 Channel Modular Bolt-On Connector Panel for RMC-2101
RMC-3101 3U, 19" Rack Mount Chassis. Holds up to 9 FOI Modules
CMA-3002 Chassis Mount Adapter for RMC-3101 Chassis. (1) per FOI Module required
PSM-3010 Spare Power Supply for RMC-3101
Industrial Solutions
RMC-3700  Environmental Enclosure for FOI Modules
CMA-3002 Chassis Mount Adapter for RMC-3101 Chassis. (1) per FOI Module required
PSM-3010 Spare Power Supply for RMC-3101

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