NMEA GPS input not giving waypoint destination

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Kahuna
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NMEA GPS input not giving waypoint destination

Post by Kahuna »

I have a new 796 install. NMEA out from 796 to EFIS (Serial 2 GPS2 NMEA). The EFIS is using the information from the 796 (GPS position) since my GRT map works (I do not have an internal GRT GPS) but for some reason the waypoint selected on the 796 does not become my waypoint destination on my GRT. I select the GPS2 to nav to on the screen, but its not doing it. Any ideas?
My expected behavior is to be able to go to flight plan, select external, and see the 796 data. I can do this with the 430 gps1, but not the 796 gps2 for some reason. Also I have wired the GRT S2 output tothe 796 in as autopilot aviaion . The 796 does not recognize this for some reason. The 796 is set for 'aviation in' format on the proper port.

My 430 using the aviation data stream to GRT works great.
Note: I had to turn the baud rate down to 4800 on the grt serial for the GRT map to start using the 796 data. at 115200, the packet counter was working and counting, but the map would not work. This surprised me.
Also just in case the waypoint identifier has not been picked up by your code, the sentence structure is here http://www8.garmin.com/support/pdf/NMEA_0183.pdf
Thanks
Kahuna
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GRT_Jeff
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Re: NMEA GPS input not giving waypoint destination

Post by GRT_Jeff »

Most NMEA0183 GPS units with flight plans send out the GPRMB message at a minimum, which contains the active waypoint. Since you are not seeing anything, I would make sure "Virtual GPS2" is turned off in the SET MENU, General Setup. GPS2 Flight Plan Source should also be External.

The baud rates on the Garmin GPS x95/x96 units are fixed by the selected format. "NMEA Out" is always 4800 baud. "NMEA & VHF Out" is always 9600.

To get a complete flight plan from the 796 to the EFIS, "NMEA Out" should be used, and the NMEA Output Mode should be set to "Normal". The "NMEA & VHF Out" mode acts like "Fast" mode, so you would not see the full flight plan. You should still see the active waypoint, however.

I haven't seen anyone try to use the "Aviation In" before. The "Autopilot (Aviation)" output always transmits the current navigation information based on the current NAV and LAT A/P modes. If you are in HDG or a VOR/ILS mode, no waypoints will be sent. If you are in GPS1 and ENAV modes, the output will include the flight plan from GPS1.
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Kahuna
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Re: NMEA GPS input not giving waypoint destination

Post by Kahuna »

Jeff,
Very key points in here.
4800, GPS2 external and vert gps off.

I ALSO had to turn GPS 1 from ext to internal.
If there is an external 1 and 2, with ext 1 powered off(this is my 430), I never see any ext 2 in the flight plan.
If I go change the setting of GPS 1 from external to internal, I see the flight plan from ext 2.
I would expect the behavior to be what ever nav I select, thats the ext I should be looking at. THis is not what Im seeing.
And with the gps2 external set, I can only copy the FP over to internal. It does not show the external FP on the map and mark it. Im gonna double check this today.
Kahuna
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GRT_Jeff
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Re: NMEA GPS input not giving waypoint destination

Post by GRT_Jeff »

I found the problem with the FLIGHT PLAN page in the software. The FLIGHT PLAN page in EXTERNAL or COPY mode will always try to use the external GPS1 flight plan first if GPS1 is set to External and Virtual GPS2 is Off. Only the FLIGHT PLAN page is affected. You should see the external GPS2 flight plan in all other places that show the waypoints and course lines. I will fix this for future software updates.
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Kahuna
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Re: NMEA GPS input not giving waypoint destination

Post by Kahuna »

Thanks Jeff. Please let me know when you have a fix in. Happy to run Beta code.
Thanks for the note. This keeps me from scratching my head any longer :geek:
Kahuna
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