The MD36/6 interface converts a DC Step (S Type) heading transmission from legacy equipment to a modern NMEA 0183 format

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The MD36/6 is a solid-state Step (S-Type) to NMEA Interface. It converts a DC Step (S-Type) transmission of a ship’s heading from legacy equipment to a modern NMEA 0183 compliant Digital Transmission format. There is an alignment facility on the unit to align the digital output of the MD36/6 to the incoming heading signal. When suitably adjusted the MD36/6 reads the step input heading to within 1/6° and re-transmits an RS422 output following the NMEA (0183) protocol with no errors.

Constructed in a robust die-cast aluminium enclosure and finished in RAL9005 Jet Black fine texture powder coat paint, the MD36/6 is designed to complement existing marine navigation equipment. Supplied for bulkhead mounting as standard, compact and rugged, the MD36/6 offers a compact Step (S-Type) to NMEA Interface solution for locations where available space is limited.

The MD36/6 Step (S-Type) to NMEA Interface from MARINE DATA; designed to be easy to install and simple to maintain.


  • Low-power, high accuracy conversion
  • Accepts a 3 line Step (S-Type) transmission input, suitable for 24-70 V dc (smoothed or unsmoothed)
  • NMEA 0183 HDT sentence transmission at 4800 Baud / 10 messages per second


  • The MD36/6 is suitable for converting from any STEP (S-Type) transmission format to a digital NMEA 0183 (IEC61162-1) transmission format. This is especially useful for retro-fitting legacy systems with modern equipment requiring a digital transmission of ships heading.


  • The MARINE DATA Product Range of Compass Repeaters
  • MD86HCU Heading Comparator Unit


  • Weight: 1.0 kg
  • Dimensions: H 222 mm; W 146 mm; D 55 mm
  • Mounting: Bulkhead mounting
  • Connections: 3x M20 Cable Glands; M4 Earth Stud
  • Construction: Aluminium alloy enclosure
  • Finish: Jet Black (RAL9005) fine texture powder coat paint


  • Power Supply: 24 V dc nominal; 4 W max; (0.12 amps @ 24 V); 18-32 V dc
  • Data input: STEP (S-Type) 3 line, common positive or negative 24-70 V dc STEP Supply, smoothed or unsmoothed
  • Data output: NMEA 0183 (IEC 61162-1); Sentence $HEHDT ,xxx.xx,T*CS; 4800 Baud; 10 messages per second


  • Performance: 1/6° accuracy (limit of STEP signal)
  • MTBF: >30,000 hours
  • Error Indication: Status LEDs on internal PCB; Status in NMEA sentence set to ‘invalid’


  • IP rating: IP54
  • Operating temp: -15°C to +55°C
  • RoHS: Compliant
  • Compass: Safe Distance 50 cm


  • Conforms with: IEC 60945; IEC 61162-1


  • Option: Custom paint colour and stainless steel cable glands – subject to MOQ

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