GPS failover

[pbennett]

The new Installation Guide (V2.0 firmware) states that a GPS failure will cause a failover to the next GPS in the priority chain (P 4-13).
The new Pilot's User Guide says that failover will not occur, and must be done manually in the setup menu (P 6-1).
When I switch off GPS1 (Garmin 695 on serial 5, generic NMEA) with GPS2 configured (Apollo GX65 on serial 4, generic aviation) I lose synthetic vision. I therefore assume the Pilot's Guide is correct.
Is there a schedule to implement failover as described in the Installation Guide?

Peter

 

[dynonsupport]

It looks like it works here, but our quick test that we just did involved 2 NMEA sources. So, a couple of things:

Are you sure that the GX65 works at all? Can you use the NAV source button to bring it up as GPS when they're both connected?

If it does, as an experiment, what happens if you switch the roles of the two GPSes so that the GX65 is primary?

Also, when it fails down (or doesn't), do you see a ? or an X on the aircraft on the map page?

 

[pbennett]

Thanks DS, I'll check your suggestions when I'm next at the hangar. I assumed the GX65 was working because the time kept ticking over when GPS1 was shut down.

N223rv, are you watching this thread? From memory you have a G696 above a GX60 in priority. Are you getting failover?

Peter

 

[n223rv]

So I just tore my panel apart for paint last night before I tried it. It isn't a real big deal to plug everything back in and try it, so I will tomorrow night. Like you said I have a 696, a GX60, and a Dynon gps all in the system. I'll try them all tomorrow night and let you know.
-Mike Kraus

 

[dynonsupport]

We set time off GPS, but we do have an internal clock that keeps working once it gets set once. If you have a battery you'll even have correct time when you turn it on. So you'll never lose time once you have it, so that's not a good test.

We do expect it to work, so whenever you can re-do the test it would be helpful. I know of a real world case where a NMEA source failed in flight on a beta tester and it failed over to a 430 so I expect it does work.

 

[n223rv]

OK, some good new, and some bad news (maybe for me...)

I hooked up the system again. GPS 1 set to Dynon, GPS 2 set to Garmin 696 and GPS 3 set to GX60. I turned off everything except the Dynon GPS and got a signal (GPS 1 working). I then turned off everything except the Garmin 696 (GPS 2 working, and GPS 2 on Navsource working). I then turned off everything except the GX60 and could not get the map to show up (RED X, and no data in GPS 3 Navsouce). I tried a few different data configurations on the SkyView with no luck. I was pretty sure I had it reading before, but maybe not..... maybe I was wrong... Any maybe this is why:

I have the GX60 also transmitting into the Garmin 696. If I put a flight plan into the GX60, that flight plan will show up on the Garmin 696, then show up on the Skyview under Navsource GPS 2 (which is the 696 input). If I look at Navsource 3 (GX60 directly into SkyView) I still get no data.

So, it appears the GX60 will talk to the 696 and feed data through the 696 to the SkyView, but the GX60 won't transmit directly to the SkyView. Is this possible???

I then did the GPS fail over test. Set up as noted above, unplugged the Dynon GPS transmit to Skyview and it automatically switched to the 696 and the SkyView continued to work and show the map. I then turned off the 696 and the SkyView got the RED X. I then plugged the Dynon GPS wire back in and got the map back. So the failsafe is working, at least between the Dynon GPS and the Garmin 696.

I am going to play with the GX60 feeding into the SkyView tonight a bit more and I will report back if I make any progress. If the SkyView is not able to read the GX60, would it be possible to request that Dynon looking at adding it? I know it is an outdated unit, but it does look like a few of us are using it It would be GREATLY appreciated....

I hope this helps!!
-Mike Kraus
RV-4 Flying with D180
RV-10 Finished wiring with Dual SkyViews!!

 

[jakej]

I'd suggest a lot of us, myself included, are using the 'Apollo' units ie GX 50,55,60,65 series.

Jake J

 

[pbennett]

Mike has saved me going into more detail. My results support his.
It doesn't matter what GPS# the GX65 is designated
Nav Source displays data fields for configured GPS's but no data in the fields.
With a 3D fix on the GX65 and the G695 off, the time does not set, the map is red X'd out and the compass calibration lat and long are red "invalid". There is clearly no communication between the GX65 and the SV.
HOWEVER.... the appropriate serial port counters are interesting. I am guessing that the G counter counts good transmissions, the R counter counts resends, and the E counter counts errors not recoverable by resend. (DS, is this correct?) The G counter ticks up by one each second, while the E and R counters sit on zero. If my guess is correct, then the GX65 and SV are talking happily at the basic transmission level, with the SV verifying no errors in transmission. However higher levels in the software are missing or not recognising data.
Apollo (Garmin now) call the output "moving map" and define it in the installation manual. Perhaps it differs from generic aviation?

Peter

 

[jlakins]

Peter
How is the transmit on your GX-65 configured?
I think the GX-65 has a MOVMAP and a MAPCOM setting for transmit.
If it is set to MAPCOM then it includes SL-40 comm data.
if yours has both settings make sure it is set to MOVMAP and try it.

Jimmie

 

[n223rv]

My GX60 is set to MOVMAP and it isn't working....
-Mike Kraus

 

[pbennett]

Likewise, I'm outputting MOVMAP.

Peter

 

[dynonsupport]

Looks like we may have a problem here. It's on our radar now - thanks for the feedback everyone (keep it coming if you discover anything new).

 

[n223rv]

Thanks for the update. Is it safe to say you plan on fixing the SkyView to accept the GX60? Or will we need to utilize another GPS to get approach functionallity? I hate to have to upgrade to a 430, but now is the time before I rivet on the upper skin between the IP and firewall. It will be 10x harder later.

Thanks again!
-Mike Kraus

 

[dynonsupport]

We'll fix it, but we can't give a firm date at this point. We're not sure why it doesn't work. We need to do some investigation. But I see no reason for you to make a hardware change.

We may need to see a serial capture of a GX unit in order to get this working, so if anybody can do that at a convenient time, that would be great. We have a lot of devices here (396, 696, 430, SL-30, Lowrance 600C) but we can't have one of everything!

 

[n223rv]

Tell me how I can do a serial capture and I can do it tonight. I also have the install manual if that helps any. It discusses the serial code in it.

-Mike

 

[dynonsupport]

The basic overview is that you need to run the serial output wire of the GX to a serial port on your PC. You then use a terminal program (like Hyperterminal, Bray, or PuTTY) to connect to the serial port and save a few seconds of data to a text file.

We can get you really specific instructions or take you through it on the phone if you're still willing. If you have a laptop, what operating system is it running? Any one will work, but instructions vary a bit.

 

[n223rv]

I'm running windoze xp. Who should I ask for when I call? I help in any way I can if you can get the GX talking to the SkyView!!!

 

[pbennett]

Mike, I'm going to try to get a serial capture today. I have a terminal emulator and I expect to be able to tap into the serial line to record the data. I'll post progress tonight.

Peter

 

[pbennett]

Reviewing the GX65 info before going to the hangar, I think we Apollo users have a fundamental problem. The GX6* moving map output includes lat, long, track, groundspeed, distance to waypoint, Xtrack error, desired track, waypoint identifier, bearing to waypoint, mag variation, and a warnings field.
No altitude information, even when the GPS has a 3D fix.
According to Dynon Support in this thread
http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1274061921
lat, long and altitude are needed for the map and synvis.
I suspect we will have to have another active GPS to provide map display and synvis when using the GX6* as the nav source.

Peter

 

[n223rv]

Yes, my intent is to use the Dynon GPS for the moving map/ synthetic vision, and the GX for the nav source. I'll check what the GX60 outputs when I get home.
-Mike