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GRT HXr autopilot config setting

Maverick972

Well Known Member
In my never ending quest for my GRT to work with my Tru Trak vision 385 and use the GPSS function I am asking our GRT experts for any help.

I have confirmed the unit is wired correctly for ARINC 429 Data so it has to be a configuration setting issue.
The input for serial port 5 is GPS1 Aviation / MapCom
The output for serial port 5 is set to (Autopilot) NMEA0182.
I believe it should be set to (Autopilot) Aviation.
I think this would provide the GPSS data I am missing?

Normally Systems generate GPSS by manipulating the Heading signals from the heading source(HSI). That is why I made the comment the GRT should generate GPSS.

If the Tru-track is getting Aviation data it makes me wonder it is generating GPSS? Then you would toggle the Tru-Track between Heading mode and GPSS.
 
Do you have the GRT ARINC module installed?

For my TruTrak Digiflight II VSGV setup, I needed the ARINC.

As I understand things, ARINC translates GRT into a language the TruTrak uses. (simple layman's terms)
 
The GRT HXr does not have the needed database to generate true gpss data. Instead, it passes thru gpss data generated by an ifr gps navigator (I use a G-420W). What are you using for a gps source? Have you wired the navigator’s gps arinc out to the HXr’s arinc in?
 
A few guesses.
1. There is a set up parameter that says ‘arinc module connected’. This was for older HS units that came without arinc, and you could later add an external module to get arinc. If your box has arinc built-in (and I thought all HXr units did) then this parameter should be ‘no’.
2. You need to look at the autopilot documentation, see if it supports NMEA 0183 format, or aviation map com format, or both, and what baud rates. NMEA can be 4800 or 9600, aviation most likely just 9600. If it supports NMEA then use that for both the in and out rs232 formats, using whatever baud rate the autopilot will accept. Otherwise use aviation at 9600, for both input and output.
3. Do you have a ‘stand alone’ switch, so the TruTrak can be driven directly by the 430W, by-passing the HXr? You should, it’s a great safety feature. Make certain the 430’s rs232 output is configured as in (2), above. I think the arinc out is ‘low speed’, iirc.
 
I’m still learning the equipment, but GRT is growing in me. I just want to have everything working to the best of its ability.

Yes, I have a auto pilot source switch, GPS / EFIS.

I also discovered that I have a GRT GPS wired to the system on serial port three, but in the settings serial port three is turned off.
Should I turn it on? How do I know gps 1 or 2?

According to the Tru Trak docs with the 430W
Output should be > Aviation 9600 baud.
 
I’m still learning the equipment, but GRT is growing in me. I just want to have everything working to the best of its ability.

Yes, I have a auto pilot source switch, GPS / EFIS.

Be sure all parameters are the same for the output of each source device--Baud rate, etc.

I also discovered that I have a GRT GPS wired to the system on serial port three, but in the settings serial port three is turned off.
Should I turn it on? How do I know gps 1 or 2?

Yes you need to turn it on. Scroll down through the serial port offerings, you may discover there is a preset for your needs.

IIRC, you assign the 1 or 2 to each GPS.

According to the Tru Trak docs with the 430W
Output should be > Aviation 9600 baud.

Have you checked the GRT site for docs on compatible equipment----there should be info there you can use. http://grtavionics.com/home/compatible-equipment/

Good luck, it will be worth it when all the ducks are marching together.
 
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One more thing...

Gnav is not illuminated while on the ground, do I have to have a GPS signal from satellites for that to be a selective option. No skylights in the hanger so the GPS will not find sats.
 
GRT settings

I'm going to guess that you bought the A/C flying, and thus weren't around to decide on initial settings. If yes, my situation is similar, as is the equipment in the A/C (430W, GRT Sport SX , and B-K xCruze100, which is basically the Vizion; the latter was installed as an upgrade from a DigiFlightII that didn't have vertical coupling).

All seem to be working together well now, but it took some time. The GRT manual isn't great about explaining just what the various settings do, why you may want to set one to be "X", etc... However, the GRT Tech Support folks ARE great at that.

You might consider making copies of all current settings, exactly what equipment you have, e.g. ARINC429 box, toggle switch to select what drives the A/P, etc..., then calling them. I think I spoke with Jeff a couple of times, and voila! If I recall, there were 2 or 3 settings that weren't what they needed to be, plus I didn't really understand what that toggle switch really did, or where it needed to point for the GRT to fully do its thing. A phone call, if you're well-aware of current settings, might save quite a bit of trial and error. Once you're set up, don't forget to make a copy of the settings and store them someplace safe, so that you can recover if something fails or becomes corrupted.
 
100% I bought it and am trying to figure it out.

I took pictures of my setting screens, so I might give Jeff a call at GRT.
 
You can download the settings to a thumb drive.

That way, if something goes off reservation, you can reset to your prior settings.
 
GOOD NEWS, Jeff from GRT identified the issue and we have a few solutions that I have to work on but my settings are good and i see some light at the end of the tunnel.

That’s customer service, thank you GRT.
 
Repl

Here is what I got from Jeff at GRT, I am posting to show the kind of super response from these folks we get and how they support us:

According to your diagram it is connected properly for GPSS data from the 430W and EFIS through a switch on the panel "Autopilot Selection Switch". It should follow the EFIS in GPSS mode when the switch has the EFIS selected. It should follow the 430W in GPSS mode when the switch has the 430W selected.

The only setting required for GPSS from the EFIS is "ARINC Transmit Rate: Low" which is correct in your photo.

The serial 5 output is not connected in your diagram. The TruTrak gets the RS232 data from the 430W only, which is fine. The GPSS mode is driven by the ARINC 429 data. The RS232 data is only used for basic GPS information like speed and track.

The TruTrak accepts both NMEA0183 and Aviation formats. If you were switching this connection between the EFIS and 430W you would use Aviation format because then it's the same format as the 430W.

If the TruTrak reads basic GPS input but won't engage GPSS with one or both sources then make sure the ARINC A's connect to A's and the B's connect to B's and they aren't getting crossed in the switch.
 
I think I will flip the wires at the switch and see what happens.

The idea of randomly flipping wires makes me cringe, but I think there’s no harm in this particular case. The right way, of course, is to remove the connectors from gps, efis, autopilot, very carefully (use a magnifying glass) locate the proper pins (e.g. ‘arinc A’), and use an ohmmeter to verify connections from gps to switch to autopilot, etc.

As an aside (I know you were not the builder), builders make exactly these kind of mistakes (mis-wiring) often enough - sometimes destroying avionics - that some manufacturers will not honor any warrantee if you build your own wiring harness. It’s not hard, but does require care.
 
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