Avidyne IFD540 Pilot's Manual page 36

Independent Data (Dual IFD Operations)
The following list of data will never be shared between two IFDs
no matter how they are configured:
 IFD page and tab selection;
 Map view, range, declutter, and overlay settings;
 Chart extent box depiction on map;
 Nav Source selection;
 Com/Nav settings (e.g. 8.33 vs 25 kHz spacing);
 Com/Nav frequency selections (therefore no
cross-side tuning or display);
 Nav deviation data (therefore no navigation
miscompare alerts are provided);
 Local CAS alerts;
 Datablock configuration;
 Chart displayed;
 Electronic Checklists data and state;
 Calculators and Utilities data.
.
NOTE
Data Sharing Tolerates Inconsistent Databases
While Avidyne strongly recommends the databases
on each IFD be kept up-to-date and on the same
cycle, data sharing between IFDs as defined above
in "Data Sharing (Dual IFD Operations)" is not
disabled when different data cycles are present on
the two IFDs.
1-30 System Overview