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GTX-327 AIRBORNE option

Scott Will

Scott Will

Well Known Member
The GTX-327 manual states that you can use two sources to automatically determine if the aircraft is airborne - a squat switch or GPS. It doesn't say much about the GPS option or how to wire forit.

Has anybody gotten the GTX-327 to automatically turn to ALT when airborne using a GPS, specifically a 296/396/496 or the internal GRT EFIS? Do you just hook up the serial out of the GPS? If so, to what pin? My GRT is already providing the grey code output for altitude. Appreciate it if I can get the automatic airborne feature to work!

Thanks in advance!
 
I'd make sure that Squat switch setting is set to NO and that Auto Standby is set to ON in the config pages.

You'd use pin 2 or 19 (depending which one you already used for GRT) in case you want to bring another source in... but I'd think/hope that GRT alone should work (haven't tried it yet here, though).
 
It is working in my Rocket that way, but I use a Garmin 430 to drive it. It is connected to Pin 02. I would look for a RS232 OUT pin from the GPS that is configurable for airspeed and use that pin to drive pin 02 on the transponder.
 
Scott Will said:
Has anybody gotten the GTX-327 to automatically turn to ALT when airborne using a GPS, specifically a 296/396/496 or the internal GRT EFIS?
Click to expand...
Scott,

I don't know about the GRT, but I'm fairly sure the 296/396/etc do not output the data the transponder is looking for. As Randy said, the 327/330 are designed to get data from a 430 or other similar panel-mount GPS.

mcb
 
reading 430 manual

I'm looking at the 430 manual right now. On page 5-4 Rev M it says there are Channel Outputs for Aviation data (serial position, altitude, velocity, and nav data) to the following units... and it lists the GTX327 transponder and even the GPS MAP 195 or GPS Pilot III.

So I guess maybe we can try taking the serial GPS output to the transponder?

Scott
 
gpsmap 296 yes you can

I have my '296 sending data to my GRT EFIS and my GRT EFIS talking to my GTX327 as the encoder for pressure altitude. I never gave it much thought, but it automatically goes from standby to fully on when I take off. I think there is a setting on the 327 for this but as I recall, it's the default. I don't know if you can wire it direct from GPS to 327, though. The connection from the EFIS to the 327 is serial as I recall. I think that may be important.
 
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Must have been Default....

Scott,

I am feeding my 327 from my GRT as well (using the serial data - couldn't get the gray-code to work back then), and the 327 always goes to "alt" on it's own on take-off. I think it must have been by default, because I don't remember setting it. In truth, I don't know if it is doing it on altitude change or gorundspeed....haven't looked at the manual recently.

Paul
 
Howard/Paul... are you using Aviation data format or NMEA 0183 format? Pretty sure I have mine set to NMEA as that is what the Trutrak A/P takes. I also have my GRT configured to send the altitude to the GTX-327. That's working great. I have it set up per GRT's instructions.
 
Here's the straight goods: The 296/396/496 does not talk to the GTX327 for auto-ALT. I tried it, does not work and Garmin confirms this.

However, the 327 will automatically switch to ALT mode on it's own after take-off. I think it detects the altitude change and assumes that you are flying. For obvious reasons, it won't do auto-standby.

I'm actually going to turn this feature off in my 327 because it interferes with formation flying when only lead is supposed to squawk.

Vern Little
 
Mine is wired to the Dynon for the encoder and nothing else and it goes to ALT automatically. It must just figure when you are climbing you must be flying and it switches.

Scott
#90598 - N598SD Flying - 89 hours
 
It's in the book..

http://www.garmin.com/manuals/GTX327Transponder_PilotsGuide.pdf

Bottom of page 7. I couldn't figure out how to copy and paste this one. It's user configurable, but it must be in the installation guide how to do it. There is also something in here about how to get into configuration mode.
1. press and hold FUNC while powering on,
2. use START, STOP and CRSR keys to get what you want.
I know I did this at least once.

So, I don't think it's about the data from the GPS. Rather, it's about configuration of the 327. Assuming, of course, that pressure altitude is correctly displayed to begin with.
 
I got word from GRT that if you have the GRT sending Fuel Air Data Z then the GTX327 can automatically switch to ALT/STBY. Do you need to lines for this or does it run off the one pin for RS-232 input?

I tried setting up the GTX327 using the menus (GPS, Auto STBY ON) but it didn't work yesterday. It is getting the correct altitude info from GRT EFIS.

Thanks!
 
GTX-327 automatically detects take off...

The unit does the standby to ALT mode all by itself. It looks for a climb rate of greater that 500 feet-per-minute. That value is programmable per the instructions in the manual.

By the way, if you land at an airport squawking a code other than 1200, be sure to reset to 1200 or the new code before departure. The previous code does not return to 1200 after shutdown and restart. Ask me how I know.

Jerry K. Thorne
East Ridge, TN
RV-9A N2PZ
 
n2prise said:
By the way, if you land at an airport squawking a code other than 1200, be sure to reset to 1200 or the new code before departure. The previous code does not return to 1200 after shutdown and restart. Ask me how I know.
Click to expand...
how about if I ask you why you don't have a squawk code check in your cockpit preparation or pre-takeoff checklist...?

:D :D

Ciao, Luca
 
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