Simrad IS20 Manual page 55

Connecting IS20 to an NMEA0183 output unit
The IS20 instrument may be used as repeater for data
from a device with an NMEA0183 output port (NMEA
"talker").
Use a repeater that is dedicated for the type of data you
want to present and the way you want it presented, i.e.
digital or analog, multiple data from a GPS/Chart plotter
or heading from a compass.
Use the NMEA0183 Interface cable (part no 22098495) to
connect an NMEA0183 output device to IS20.
Installation | 55