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Garmin GTX-327 reading

L

Larry Parham

Well Known Member
On my 327 I no longer get a pressure altitude reading on the readout. Flight Following can not read my altitude. All hooked up ok. Any ideas out there?
 
327

Provided there is nothing wrong with the transponder:

Do you have a blind encoder? If the wires are still attached it has gone bad or need servicing. Do you have a dynon that sends pressure altitude information to your Garman? Make sure it still programmed for number four and the RS 232 and ground are still attached to the 327. Other device that sends altitude to the transponder?

Yes, make sure you have ALT displayed, which is achieved by pressing the AL T button. Off,On,Alt are the buttons on L side.
 
If you boot up in the setup mode, you can check the serial port settings and the Gray code readout if there is a Gray code altitude source. There is a screen that will show what serial altitude info you are getting. Whatever source you have, either way you have a source that is not sending the right signal or you have a bad wire.

The only other option I can see is that your 327 is not interpreting the data correctly. Try borrowing a 327 and see if it works.
 
Failed to clarify, THE 327 WILL NOT DISPLAY ON THE GROUND either. Alt is pressed and my understanding the unit cant be programed incorrectly, to not display alt. I would not prefer Jessee to be right, as that will be the most expensive
 
The unit can be programmed incorrectly if RS-232 is used. I'm not sure on the Gray code input. What format is your encoder output?
 
I'll bet the unit is fine. It's your efis or whatever is encoding the altitude that has the problem. Been down this road before. Where is it getting the altitude info from?

Erich
 
Garmin 327

My Garmin 327 is being fed by the GRT pressure sensor serial (5-31 inches). Removed the cover, not much to it. The only thing inside that isn't readily available is the sensor. I was in the program section the other day, did not think I changed anything?
 
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I was guessing that might be the case. I had the same problem on my Sport SX. There is a chip on the GRT boards that is specific to the serial ports. GRT got a batch of them that were bad awhile back. They can fix you up but you will have to send the unit in.

Erich
 
If it was working then stopped and you were in the GRT at that time, that sounds like the problem. Check for loose wires and changed settings.
 
Not directly related but thought someone out there might benefit from my stupidity. Have had a 327 with ACK encoder for twelve years in my 6A. Installed a GRT Sport several years ago and wired it to the 327. ACK was working fine so left it hooked up. Started getting complaints from ATC about altitude readouts so decided to use the GRT encoder. After many attempts to program the 327, I decided to read the manual more closely. Turns out I had never upgraded the software and it wouldn't recognize the GRT. Local avionics shop did the upgrade no charge. Can't remember the software version but I believe it's dated 2011. Now the GRT encoder is inputing the 327. Nice thing is that the 327 searches for the altitude source starting with serial then gray code so the ACK still functions as a backup. I believe this new software version is also necessary if there is to be any ADS-B involvement. So anyone out there with an older 327, you may want to upgrade the software. Hope this helps someone.
 
There is an RS 232 in number one and number two in the configuration pages. If you inadvertently deleted that you are receiving from the GRT on the specific 232 in (1 or 2)that the GRT is wired to....that could do it.
 
Navworx and Freeflight can use 327 as ADS-B

transponder source ---- Navworx through their transmonde device and Freeflight by "mining" the mode C. (at least that is my understanding).

Ron
 
RONSIM said:
transponder source ---- Navworx through their transmonde device and Freeflight by "mining" the mode C. (at least that is my understanding).

Ron
Click to expand...

The 327 can also output a Remote signal that will set mode and squawk code on the Freeflight and the Navworx.
 
Garmin GTX-327 FIXED

Well a long story short, it was a entry in the settings menu that was missing.
Now for a short story long the 327 was never the problem. A month ago my battery voltage ran down and I lost my #2 GRT and I had to copy all the info on GRT #1 to #2. Pin 19 on the 327 is fed by pin 5 of GRT 2 so in the settings menu I had to add "fuel air data z format" and add "9600" for the port rate and my alt on the 327 just popped up. THANKS FOR ALL THE HELP
 
Shot in the dark here, but when I changed my GTX-327 from parallel to serial altitude input, every once in a while the altitude readout on the screen would be +/- a thousand feet low and ATC told me "Stop altitude squawk". It hasn't happened recently but the last time it did (on the ground), I cycled my Avionics Master and the altitude came up OK. I figure it had something to to with the timing between my altitude source (Dynon D-6) and the transponder powering up. These days, when doing my preflight checklist, I glance at the altitude displayed on the GTX-327.
 
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