RS-232 (MIL-STD-188C) Datacom Products
FiberPlex FOI-2191 Fiber Optic Isolator/Converter/Modem - TIA-232/MIL-STD-188C; mission critical packaging

Packed in rugged military style metal enclosures, the FOI-2191 Series are RS-232/Serial Fiber Converters supporting rates up to 128 kbps

Used in pairs, the FOI-2191 (to DTE) and FOI-2911 (to DCE) provide end-to-end conversion, extension, and electrical isolation of RS-232 circuits up to a maximum data rate of 128 kbps. Multimode optics can extend the distance to 2km, while singlemode optics can extend the distance to 20km. These units are transparent to all handshaking protocols, and can accept data and clock signals. A regeneration switch on the FOI-2191 enables users to toggle between synchronous applications that require send timing (ST), and asynchronous or synchronous applications that require terminal timing (TT).

For compatibility with MIL-STD-188C, the TD and RD can be inverted through either unit by a switch. They support tail circuit and null modem functions by using two of the same FOI units. An alternate interface (V.35 or RS-422) may be installed at the opposite end, allowing the user to create a fully isolated interface converter. The units can be used in areas of high electrical noise or in and out of RF shielded enclosures. The fiber optic cable is not susceptible to interference caused by impulse noise, crosstalk, or EMI. Patton recommends “R” units for high security applications because they have added filtering and shielding for RFI suppression.

FOI version units can be mounted in several redundant powering chassis; rack and wall mount options including Tempest and NEMA alternatives.

A typical link consists of an FOI-2191 at the Data Communication Equipment (DCE) and an FOI-2911 at the Data Terminal Equipment (DTE) with a duplex fiber optic cable in between.

FOI-2191 applications

  • Serial Data (TIA/EIA-422, MIL-STD-188-114A and FED STD 1030A) Fiber Modem and Converter
  • Multimode extension of up to 1.2 miles (2 km), singlemode extension up to 12.4 miles (20 km)
  • Supports Data Rates from DC to 256 kbps
  • Tail circuit and null modem functions for DCE to DCE or DTE to DTE
  • Pairs with other FOI with V.35 or RS-232 interfaces for interface conversion
  • Rugged metal enclosures with RFI shielding
  • Delivers 4 channels of control signals and relay closures with 2 channels of asynchronous or synchronous RS-232 communications over fiber


Ordering information for this product is not publicly available at this time.
Please accept our apology as we regret any inconvenience to you.

For more information
about the availability of this product and/or alternative solutions,
please contact Patton's Product Management team at or +1 301 975 1000

Sales: / +1 301 975 1000
Support: / +1 301 975 1007
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