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Digitrak won't track GPS flight plan

LettersFromFlyoverCountry

LettersFromFlyoverCountry

Well Known Member
I have a TruTrak Digitrak, wing leveler (not altitude) that is connected to the Garmin 296. The 296 is also providing data to the Dynon D100.

I had noticed the HSI taking too much time to "recover" on turns and also the Digitrak, while doing a wonderful job of holding heading, wasn't tracking the 296 when it had an active flight plan.

I doublechecked all the settings and found only one "mistake."

While the TruTrak instructions says the NMEA In/NMEA Out on Com1 can either be Fast or Normal, my pal Mike Hilger says it needs to be on normal because fast output drops serial sentences the A/P needs.

I also made sure the subcategories were set to "off" as the instructions require.

Also, doublechecked the AP to make sure the baud rate was 4800.

As before, the AP display said "OFF," which indicates the presence of good GPS data. And the Dynon was displaying good GPS data.

As I taxiied to the runup area, I noticed the "OFF" had changed to ---, indicating no GPS data, but upon takeoff, it was again showing "OFF" and everything was normal.

The Dynon data was rock solid. With the change, the HSI display had settled down nicely and was working great. Some additional information also appeared that hadn't appeared before (note to self: Read the instructions in the Dynon manual and find out what that information is)

I guess in the big scheme of things, it's not a big deal. It's not like I really need the function too much. I can just push it "on" and let track heading if there's something I need to concern myself with inside the cabin. But I kinda want a "hey, that's cool" moment.

Any ideas?
 
Mine too.

I recently installed a digitrak and mine will not track a flight plan either. Suppose to get a "F" on the display. I do get the OFF. Mine is connected to a 696. Mine tries to hold heading but continues to turn left a few degrees every few minutes.

I have not spent much time troubleshooting yet, but I am interested in the feedback to your problem. I talked to Trutrak a couple of times and they were very helpful, but I am not done troubleshooting.
 
Bob,

Actually, the autpilot prefers the fast setting as that gives a 1 Hz update instead of a 1/2 Hz, which can cause wandering.

So you're getting a solid GPS track but no flashing -F-? Are there any other devices connected to the serial line other than the D100?

Geeman,

Try your 696 with NMEA In/NMEA Out at 4800 baud. Also, make sure your torque is set to 12.
 
Not ignoring you, Lucas, but I'm going to have to take the plane back up and check. I'll shoot a short video of what's being displayed and when. I just have to finish fixing a busted intersection fairing and get the temps here up a little higher.

There's a 327 transponder in the system that has that function where it switches to ALT on takeoff automatically. I'll have to see where that's getting its data from (I can't remember) but other than that (maybe) and the Dynon D100, there's nothing else using the serial.
 
Now that I think on it, the reason I had to use "Normal" output from my 296 wasn't the Pictorial Pilot I had. The Dynon D10A that was in my panel at the time required it. My autopilot didn't wander, either.
 
Mike, until you told me to change to "normal," I wasn't getting a CDI indicator on the D100 (the magenta line), which only reports when it's getting a good flight plan data from the GPS.
 
The Dynon HSI won't work correctly if the NEMA stream is set to FAST.

This has always been a conflict with the suggestions provided by TT for best performance.
 
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Sorry to be so late getting back to you. I've only been able to get the door at the hangar open this week. But just sitting on the ground, I get OFF when the unit is disengaged. I understand this means there's a valid GPS signal. When I activate a route on the 296 and engage the autopilot, I get a _|_|_ which I understand means there is no GPS signal present. Again, I'm not moving; I'm just sittting in the plane.

Weather permitting, I'm hoping to fly to Phoenix on Tuesday and I can play some more.kn
 
Probably not what is causing your problem but this bit me in the past. If you set up most Garmin units to TIS/In/NMEA & VHF out the unit sends all data out at 9600 baud regardless of what baud rate you preselect. If you do have the above function active your autopilot will have to be set to 9600 baud for data to be usable.

George
 
Yes, it's set according to TT instrux. It's providing good data b/c it shows up on my Dynon D100 fine.

I think I know what I'm doing wrong. I don't think I'm putting it into "nav mode" properly. I'll know more when I take her up on Tuesday.
 
I have the exact same set-up (Digitrak with 296). I can check my settingf for you tonight, but in genersal I would assume it is comunicating OK if it is able to hold track when you turn it on. You will see an "F" if it is tracking a flight plan. to to this you turn it on then push both arrow buttons at the exact same time. - also, don't forget that you have to power it up whith the plane level and stationary.
If you have a spicific question about a setting please let me know.

Keith
 
The settings are fine. I suspect the problem is I thought just engaging the autopilot would track the FP. I missed the "push both arrows" part in the instructions.

Was hoping to fly to Phoenix today and test it out but canceled the trip amid concerns for the weather on the flight back Friday. I might be too risk averse to be a cross country pilot. (But that's a whole 'nother thread).
 
Bob, if it makes you feel any better, I recently switched from an obsolete TruTrak AP to a newer one. In most of my early flights with the newer AP, I find I have engaged the AP but not switched to NAV mode.

I never seemed to forget with the older AP but there is something about the new one that just hasn't sunk in yet.
 
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