Ask a local avionics technician, you need to download the
user way-points to a database and then convert it to a
format and medium that can be entered into the new Garmin.

Already asked: the only information an important Garmin dealer here in
Italy has, is that a 430/530 can be cross-conneted and the waypoints can
be saved when the other unit has to be serviced.

Database conversion and/or a program on PC is my job: I alreday did it
for a couple of Garmin handhelds, with DOCUMENTED protocol.

The GNS530 database will be "protected" since it is a
certified unit, but you should be able to create a "virtual
GNS530" using a laptop computer and then use the cross-fill
menu to import the way-points.

See above: I need the SPECIFICATIONS for the protocol. On the
"Installation Manual" there are only few specifications, but for packets
FROM the 430 to other units. No reference at all for packets to be sent
to it :-(

On page 107 of the GNS530 manual, it says that the GNS530
can use "other equipment" in the panel, such as a joystick,
to create a waypoint.

Yes: that is the reason I am convinced it can be done.


This would be documented and a
qualified avionics shop would be able to duplicate the
output and use your database as the input.

As far as I can see, it isn't documented. May be Bendix, Honeywell and
Collins have other channels... of course!