GRT HXr autopilot config setting

[tom_AZ]

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.

[Maverick972]

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.

[Mike S]

You can download the settings to a thumb drive.

That way, if something goes off reservation, you can reset to your prior settings.

[Maverick972]

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.

[Maverick972]

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.

[Maverick972]

I think I will flip the wires at the switch and see what happens.

[BobTurner]

Originally Posted by Maverick972

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.