I am not sure on how to do it with the AFS units but I suspect it is similar.
On our units you would select the horizontal deviation source to be routed to the HSI display - anything that goes to the HSI also goes to the autopilot if it can be steered via ARINC. We are also likely to do this with a normal NMEA system soon by "faking it".
So, it's quite simple realy - you have a lot of possible sources and you simply select which one to use.
Currently we do:
GPSNAV (that would be a "goto" or route following).
Simulated VOR (fly VOR radials even if you don't have a VOR receiver - using GPS to fake it).
Simulated ILS (We call it GLS, effectively a GPS based simulation of ILS).
Then real VOR/ILS from a number of possible sources connected to either serial ports (like a SL30) or whatever you can throw at the ARINC receive ports (there are three of them so you could select from three sources on the ARINC as well).
Of course you can also select a simple heading bug as source so you can fly a simple magnetic track.
The idea really is to connect up anything you want, tell the system what you have connected and then get presented with a selection of sources in flight so you can use whatever you want at the time.
It all boils down to a very simple thing at the end of the day - regardless of source you need to tell the autopilot to fly left or right and by how much (in effect by how much to bank).
Again, I don't know the AFS at all - but there will be something in there where you can select what you want the autopilot to follow. The EFIS should kind of be a "switch" for what gets routed to the autopilot.
Concentrating on your VOR question, assuming you selected the VOR as source and you selected the required radial using the OBS knob the VOR will now send "left/right" information to the EFIS. The EFIS will also have your magnetic heading and together with the VOR CDI and the OBS has all it needs to "plot" an intercept at a suitable angle onto the radial and fly towards it right until the point where the CDI starts centering - at that point (or shortly before) the EFIS will now direct your aircraft to track the radial (so depending on your OBS bearing you will be flying towards or away from the VOR station on the chosen radial).
Quite fun - just like with the real thing, things get "wobbly" just as you overfly the VOR station.
OK, here is something you can do for free (I.e.: Even works in a recession !):
Download our Odyssey simulator. Get some free navigation data from
www.Navaid.com (which includes VOR stations) and convert that to something the simulator can use - (you create a navidata file using the free Enigma Flight Planner). Now you can configure the simulator to use "GVOR" which is the simulated GPS VOR.
You will find a GPS simulator - set it up for a suitable position and start flying in a particular direction and speed.
You will also find a autopilot simulator - switch it on. Now select a VOR station from your database and select the GVOR as source for your HSI. The HSI comes alive and you will see your simulated aircraft banking towards the selected radial - select this using the simulated knobs on the right (first select OBS as function for one of the two knobs).
If you go through the trouble of installing the terrain data and the vector maps (all of this is free for download) it gets quite neat.
The above is the short form - there is a lot to learn to get everything setup (just like in the real world), if there is interest I'll write up a step by step...
I know this perhaps is not what will happen with the AFS, but if anybody else out there wants to play with a big EFIS without spending a cent - this is one way to go...
Rainier
CEO MGL Avionics