twistedtree
Guru
I think all of this has been said in one form or another, but it might benefit others to lay it all out. When it comes to interfacing and compatibility between APs and MFDs (or other charting systems), here's what's required for the different levels of finctionality:
AP Auto Mode: This is where the AP just holds a particular heading, and it is done purely by the AP. No MFD required, so compatibility requirements. The AP just needs heading and GPS (position and COG) inputs. In fact Auto wil probably work just fine with only a heading input.
AP Nav or Track Mode: This is where the AP follows a route that is being broadcast by the MFD. This requires an MFD and it needs to send "Nav data" to the AP. These messages are standardized in both NMEA 0183 and 2000, so any AP should be able to follow the route from any MFD.
AP "Virtual" Control Panel: This is where the MFD can pop up a virtual control panel for the AP that functions similarly to a physical control panel. It typically has buttons to switch between standby, Auto, and Nav modes, adjust heading, etc. This can be used in addition to physical control panels, and sometimes completely in place of a physical control panel. This function only works if the AP and MFD are of the same brand because all this control communications is proprietary. And check with the manufacturer to be sure you have compatible models of AP and MFD.
AP Auto Mode: This is where the AP just holds a particular heading, and it is done purely by the AP. No MFD required, so compatibility requirements. The AP just needs heading and GPS (position and COG) inputs. In fact Auto wil probably work just fine with only a heading input.
AP Nav or Track Mode: This is where the AP follows a route that is being broadcast by the MFD. This requires an MFD and it needs to send "Nav data" to the AP. These messages are standardized in both NMEA 0183 and 2000, so any AP should be able to follow the route from any MFD.
AP "Virtual" Control Panel: This is where the MFD can pop up a virtual control panel for the AP that functions similarly to a physical control panel. It typically has buttons to switch between standby, Auto, and Nav modes, adjust heading, etc. This can be used in addition to physical control panels, and sometimes completely in place of a physical control panel. This function only works if the AP and MFD are of the same brand because all this control communications is proprietary. And check with the manufacturer to be sure you have compatible models of AP and MFD.