Are an E80 Classic MFD with RL80C compatible? Could they be interfaced via a HSB or Seatlk hs adapter (if it exists)? Or with a Seatalk 2 to Seatalk1? The E80 would be used as the main unit and the RL80C as the slave.
Unfortunately, E-Series Classic MFDs (E80, E120) are not designed to be interfaced to hsb/hsb2 Pathfinder Series Displays ... and certainly not in a manner which would support the degree of resource and data sharing which you have inquired about. While it is possible to interface a hsb/hsb2 Pathfinder Series Display to the same SeaTalk bus to which an E-Series Classic MFD (via its SeaTalk/Alarm Cable) has also been interfaced, communications would be limited to alphanumeric, GPS, instrument, navigational, and system status data between these systems. Correspondingly, it is not possible for E-Series Classic MFDs to share graphical data such as cartography, radar, fishfinder, or Sirius Marine Weather with any product other than another E-Series Classic MFD.