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Trio Pro Pilot and GNS 430W

Kevin Horton

Kevin Horton

Well Known Member
I'm debugging my recently installed Trio Pro Pilot autopilot, and have a question about its behaviour when connected to a Garmin GNS 430W for anyone else who has this combination.

On my aircraft, the Trio is not showing any GPS info until I have put a flight plan in the GNS 430W. If there is no flight plan in the GPS, the Trio shows a "No GPS" message, and will not work in CRS mode. It starts working as soon as I enter a flight plan.

I just checked the serial (originally I called this NMEA, but that was a misuse of the term) data that I recorded on one of my test flights, and I see that the GPS does put out track and ground speed even if there is no flight plan, so that data should be available to the Trio. I'm wondering if something is messed up in the serial (was NMEA) communication from the GPS to the Trio, either a wiring problem or a GPS serial port configuration issue.

For anyone who has a Garmin GNS 430W and a Trio Pro Pilot - please confirm that your Trio shows a connection to the GPS even if there is no flight plan. It should work in CRS mode.

If someone else confirms their system works with no GPS flight plan, then I'll experiment with different serial port options, and check the wiring if that doesn't do it.
 
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Kevin,
This is correct.
Also, other systems that are listening to the aviation stream(there is no NMEA on a 430 avail I dont think), will also be in standby mode.
An MX20 is dead until a flightplan is entered into the 430 for example.
 
Something is amiss.....how can the 430W be used as an approved/certified ADS-B out position source if will only output position/track/GS that can only be used when there is an active flight plan???
 
This doesn't seem right - what format do you have the 430 serial stream in?

I'm planning the same configuration, and was hoping to use the "AVTN NO ALT" format for the serial connection between the 430 and the Trio.

Also, Trio provides excellent support, I'm sure they know the answer. Please keep us posted with your results.

Also, how did you record the NMEA data? That seems like a cool capability.
 
You can use just about any laptop with numerous software packages to capture serial data.

Windows comes with Hyperterminal that works fine for this.
 
Brantel said:
Something is amiss.....how can the 430W be used as an approved/certified ADS-B out position source if will only output position/track/GS that can only be used when there is an active flight plan???
Click to expand...
The GNS 430 outputs RS-232 (was NMEA, but that was an error) data on the serial ports (if so configured) with position, GPS altitude, track and ground speed about 30 seconds after power up, even if there is no flight plan. I have recorded this data many times, so I know it is available even when no flight plan is entered. I can tell when a flight plan is in the GPS because then the serial data also has desired track, cross track error, active waypoint name, distance to waypoint, etc.

I cobbled together a data recording capability for serial data from my GNS 430, EIS 4000 and Dynon EFIS, plus an event marker. Each of these is a separate serial input into a 4 port Keyspan USB to serial adapter which connects to a laptop computer. I wrote some python scripts that swallow all the serial data, adding a time stamp to each record so I can time sync the data from different inputs. Data from each device goes in a separate file. I run another python script post-flight that merges these into a single file time synced file which I can import into a spreadsheet, or other data analysis programs.
 
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I'm not aware of any certified navigators that output NMEA formatted data. Perhaps you are thinking of the de facto standard "Aviation" RS-232 format? (sometimes called Argus moving map format)

mcb
 
Kahuna said:
Kevin,
This is correct.
Also, other systems that are listening to the aviation stream(there is no NMEA on a 430 avail I dont think), will also be in standby mode.
An MX20 is dead until a flightplan is entered into the 430 for example.
Click to expand...
Kahuna,

I'm more than a bit confused by your response. My 430 definitely spits out RS-232 serial (was NMEA, but that is a misuse of the term) data starting about 30 seconds after power up, even if no flight plan has been entered. I know the data is output from the 430 as I have recorded it.

Does the MX20 show your current position on the map, track and ground speed if there is no flight plan in the 430?

You've got a Trio Pro Pilot, IIRC. What GPS info does it show before you enter a flight plan in the GPS?
 
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mburch said:
I'm not aware of any certified navigators that output NMEA formatted data. Perhaps you are thinking of the de facto standard "Aviation" RS-232 format? (sometimes called Argus moving map format)
Click to expand...
OK, I shouldn't be calling it NMEA. I thought that was what it is, but now that I look at the GNS 430W Installation Manual again I see that they don't call it NMEA. I was referring to what they call Aviation RS-232 format. Sorry for the confusion.
 
I have the EZPilot and everything is as you say--no flight plan, "No GPS" warning on the Trio. This really bugged me at first, but I just dump in a junk "direct to" if I think I need it. Usually I have a flight plan up anyway, so I don't see it as a problem. When I put in the 430, it did cause me quite a few headaches until I realized what the Trio needed. If I had to guess, the Trio needs something to give reference to. With my other GPS switched into the Trio, it says "No Flight Plan." Really no idea why the difference...

Bob
 
Kevin, it would make sense that without any flight plan in there is no guidance being sent to the Pro Pilot. I am assuming you are using an ARINC module as well. Best thing would be to give Chuck a call at Trio tomorrow. They are using a 400 series navigator connected to the Pro Pilot, ARINC module, and a GRT Sport. And you got it right that the serial data is RS232.
 
Kevin Horton said:
Kahuna,

I'm more than a bit confused by your response. My 430 definitely spits out RS-232 serial (was NMEA, but that is a misuse of the term) data starting about 30 seconds after power up, even if no flight plan has been entered. I know the data is output from the 430 as I have recorded it.

Does the MX20 show your current position on the map, track and ground speed if there is no flight plan in the 430?

You've got a Trio Pro Pilot, IIRC. What GPS info does it show before you enter a flight plan in the GPS?
Click to expand...

Kevin,
The 430 is not outputting gps position if there is no destination waypoint, either by FP or by direct to. I do no tknow why this is, it just is.

Any device slaved to it that needs the GPS position to operate, will be dead without a waypoint or fp in.

As I mentioned, the 430 I dont think has a NMEA stream, not that that has any relevance on the dicsussion.

Your 430 and trio are operating fine.
 
videobobk said:
I have the EZPilot and everything is as you say--no flight plan, "No GPS" warning on the Trio.
Click to expand...

Thanks for the info Bob. I can certainly live with it like this, as it only takes a few seconds to do a Direct-To somewhere if I don't have a real flight plan in mind, but want to use CRS mode.

I understand why TRK mode can't be available, as there is no track line to provide guidance to. But, I expected CRS mode to be available, as all it needs is the current GPS track.

The current version of the Pro Pilot Installation and Operation manual says that CRS mode should be available if GPS data is available, even if no flight plan is entered. In this case there should be a "NO FLTPLN" message. I'll contact Trio to see what they say. Maybe they have a bug with the current version of the software.
 
Actually let me clarify.
There are labels null in the stream if there is no dest waypoint or FP.
Which labels I do not know, but you could pretty easily tell on a capture.
Just as an example, it could be that with no destination, the 430 will send null on label 312 ground speed. Labels can be found on the serial data function section of the 430 manuals.

If your Trio looks at that label and its required for operation, it could error out with a 'no gps' even though only one particular label is missing.

Now I can also tell you that many slaved 430 devices, the Trio, MX20, and others are dead until a waypoint is entered. Which labels are they looking at? I dunno.

If I had to hesitate a guess, and this is a total swag, on why it operates this a way, Id say its due to the original operating requirements of the stream. It was likely only used to drive autopilots in its original inception. It was only later in the 430's life where its own gps receiver was used as a master for other devices in the cockpit. And you know how programmers get when you want a change.
 
Kahuna said:
Actually let me clarify.
There are labels null in the stream if there is no dest waypoint or FP.
Which labels I do not know, but you could pretty easily tell on a capture.
Just as an example, it could be that with no destination, the 430 will send null on label 312 ground speed. Labels can be found on the serial data function section of the 430 manuals.
Click to expand...
I've recorded the GNS 430 serial stream many times. It outputs lat, long, track, ground speed, GPS altitude and magnetic variation as soon as the GPS has a position lock. If you input a flight plan or a Direct-To, the serial stream gets many additional items.
 
Trio/GPS question

I have Trio servos mounted and am awhile from ordering my avionics. Can you tell me if this is an issue with the Trio -
Garmin 430 specifically, a Garmin 400 series problem, or do all GPS brands operate this way?
Regards
 
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Now that I think about it, there may be some differences in the Trio's requirements. Way-Back-When Trio and AvMap IV didn't talk to one another very well. I beta tested software from AvMap until they worked it all out. The AvMap would work fine on other APs, but not Trio. This began with a software update from AvMap. It was something missing in the data stream (had to do with confirming accuracy, IIRC.) Perhaps this is the same thing, or perhaps unrelated. Trio was adamant that they had it right! I wonder if the 430W does the same thing with TruTrak? I do appreciate the Trio for what it does and can live with the rest.

Bob
 
This is most likely a bug on the Trio. There is no reason why you should not be able to couple the AP to the current GPS ground track without an active FP or Direct to active. I have never heard of this limitation with TT or Dynon with a 430.
 
Wondering if the 430 sends the data out without a flight plan or direct-to programed in. On page 18 of the Pro Pilot manual under the Preflight Power Up chapter it talks about this. Do you get the GPS data when you are moving?
 
Capflyer said:
Wondering if the 430 sends the data out without a flight plan or direct-to programed in. On page 18 of the Pro Pilot manual under the Preflight Power Up chapter it talks about this. Do you get the GPS data when you are moving?
Click to expand...
The GNS 430 serial data I've recorded shows that it starts sending out RS-232 data as soon as it gets a GPS position, even if the ground speed is zero.
 
Call the amigos...

...they should be able to tell you what's happening. I'm interested in what they say as well.
 
I just got off the phone after talking to one of the guys at Trio - I didn't catch his name.

He says that the autopilot behaviour is different depending on whether the GNS 430 has the WAAS upgrade or not. With the original GNS 430, the autopilot behaves as described in the manual. If no GPS signal is received, you get a "NO GPS" message. If GPS info is received, but the GPS has no flight plan, you get a "NO FLTPLN" message.

But, once the WAAS upgrades hit the field, Trio started getting reports of "NO GPS" messages unless there was a GPS flight plan. Garmin claims there were no changes in the info sent by the GPS, but something must be different. Trio says that switching the GPS's RS-232 format to "Aviation No Alt" has been reported to help by some users. I currently have "Aviation" as the RS-232 format. I'll try "Aviation No Alt" next time I go flying.
 
On today's flight I changed the GNS 430 RS-232 output format to "Aviation No Alt". Now the autopilot works as described in the docs (except the message spelling is different). It shows a "NO FPLAN" message when the GPS has a valid position, but no flight plan has been entered. CRS mode works in this condition.
 
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