Fiber Optical Converter IEEE C37.94 MM/SM

21-203 is a protocol independent optical-electrical-optical long haul converter link with data integrity control for high reliability. The incoming multimode signal is sampled and packaged in 4B/5B code before transmission on the singlemode interface.

Incoming singlemode signal is decoded and error detected before reassembled and transmitted out the multimode interface. This conversion method offers a better (lower) error rate for low speed signals compared to transparent converters suitable only for high speed signals.


  • Standards compliant for power substation installation
  • Protocol independent up to 2Mbit/s MM 850nm (IEEE C37.94) (C3794)
  • Power budget 30dB in SM 1550nm
  • Single supply range from 48VDC to 250VDC or 110VAC to 230VAC
  • 19” mounting with only 200mm depth
  • Range typical up to 120km

Technical Data

Fiber optical link – Multimode Interface

  • Wavelength: 850nm
  • Fiber optical connector: LC
  • Optical system budget: 15dB in multimode fiber 62.5/125um.
  • Typical distance: 2km

Fiber optic link – Singlemode Interface

  • Wavelength: 1550nm.
  • Fiber optical connector: LC
  • Optical system budget: 21-203 30dB in singlemode fiber 9/125um.
  • Optical system budget: 21-203M/R 46dB in singlemode fiber 9/125um.
  • Optical system budget: 21-203L/R 50dB in singlemode fiber 9/125um.
  • Typical distance: Up to 200 km with typical 0,20 dB/km
  • Fiber optic protocol 125Mbit/s, multimode data is sampled at 25MSamples/s and coded with 4B/5B coding.

Power Supply

  • DC: 48V DC to 250V DC, ±20%
  • AC: 110VAC to 230VAC ±20%, 50−60 Hz
  • AC/DC-connector: IEC 320, 3 pin.
  • Power consumption: <15W


  • Temperature range: Operating, -20 to +55 oC. Storage, -40 to +85 oC.
  • Relative humidity: Operating, 5 to 95 % . Storage, 5 to 95 % non condensing.

CE compliance

  • Immunity: EN 61000-6-2, EN 61000-6-4, EN 50178


  • Vibration: IEC 60255-21-1, IEC 60255-21-2, IEC 60255-21-3

EMC compliance

  • IEC 60255-22-1, IEC 60255-22-2,
  • IEC 60255-22-3,IEC 60255-22-4


  • IEC 60255 / EN 50178 , IEC 60255-5, IEC 60255-5

Dimensions and Weight

  • Physical size: Height 45 mm, Width 483 mm, Depth 173 mm
  • Weight: 3 kg


FS17029 Datasheet 21-203 Fiber optic IEEE C37.94 MM-SM Converter R6

Technical Manual


Associated products