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G5 to GTX 327 - RS232 Data

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Hey all! Sorry if this has been addressed somewhere, i promised i searched for it but couldn't find it.

Anyway- I have a G5 in my plane and recently bought a GTX327 to replace my older Bendix/King. I have an Altitude Encoder that is going bad and needs replaced also.

So the question is; Can I use the Garmin G5 RS232 data as an Altitude (Encoder) Source in place of buying a new encoder? I have read that the G5 supplies Alt info via the RS232 data wire and the GTX327 can cypher that info.

I can not find any hard information (yes/no) on this so figured one of you would have the answer.

Found this on the Garmin G5 page.

<Does the Garmin G5 have an Altitude Encoder output which can be used for Mode C Transponder reply?

Yes. The G5 outputs altitude encoder data to a compatible transponder. Both Icarus and Shadin-format messages are output when using this setting. Please note that the transponder must be able to read RS-232 data>



Thanks in advance! HAPPY NEW YEAR!
 
Hello,

Yes, this will work if the G5 serial port is available.

Page 7-5 of the current Rev. 8 G5 Installation Manual shows how to wire a G5 to a GTX 327 and use it to supply altitude data to the GTX.

As shown on this drawing, configure the G5 RS-232 Output for "Altitude Encoder" and the GTX 327 RS-232 Input for "Icarus Alt".

Steve
 
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+1 on Steve’s answer.
No need for an encoder, neither external nor the one for the 375... the G5 will provide that info.
 
+1 on Steve’s answer.
No need for an encoder, neither external nor the one for the 375... the G5 will provide that info.

Not to thread drift too much, but Dan is right.

If you have a G5 system with a Garmin GNX 375 or other Garmin Mode S ADS-B transponder like the GTX 335/345, these transponders automatically receive altitude data from the G5 over ARINC 429 (via the GAD 29), so there no need to connect the G5 RS-232 to the GTX.

If you have dual G5 units, you even have backup altitude data for the transponder via the CAN bus connection to the GAD 29.

ACtC-3fbzBDfc3YHLXOq_4Sd7D-KAkzH-lKILnPSZkwE-6CXPG0UIby7-X0ydg8y65QtTQ-wPCtZhhqYgnW6wNjoR1mzRmMcxZW_rpsn4nKE9ECbAMTN_FSkdlJHj6fdsS8qKslgJVOqy4WyEMGx1S9ZHEf3=w640


Steve
 
Here is how you do it. Note that you can still send navigation data to the G5 with Pin 4 (RS232 RX) since it is still available. You can configure the G5's RX and TX settings to different serial formats. For the altitude data set Pin 5 (RS 232 TX) to "altitude" format and then set the GTX 327 Pin 19 (RX 1) to "Icarus" format. You can also split the altitude signal by teeing into the wire to send it to another device if desired.

oli1lSi.jpg
 
Here is how you do it. Note that you can still send navigation data to the G5 with Pin 4 (RS232 RX) since it is still available. You can configure the G5's RX and TX settings to different serial formats. For the altitude data set Pin 5 (RS 232 TX) to "altitude" format and then set the GTX 327 Pin 19 (RX 1) to "Icarus" format. You can also split the altitude signal by teeing into the wire to send it to another device if desired.

oli1lSi.jpg

Thank you so much! Your diagram will be printed and used for my install! Much appreciated and thanks for taking the time to respond.
 
Here is how you do it. Note that you can still send navigation data to the G5 with Pin 4 (RS232 RX) since it is still available. You can configure the G5's RX and TX settings to different serial formats. For the altitude data set Pin 5 (RS 232 TX) to "altitude" format and then set the GTX 327 Pin 19 (RX 1) to "Icarus" format. You can also split the altitude signal by teeing into the wire to send it to another device if desired.

oli1lSi.jpg

Question guys; So I installed and configured today as the install doc's and suggestions stated. When sitting on the ramp my GTX won't display "pressure alt", and haven't flown so not sure if it does it in flight. Is this normal? Or should it at least display the alt I am sitting at? I noticed the transponder in my other plane only displays when in flight.

Just want to make sure its correct before i go get tested.

Thanks,
 
Yes. You should see pressure altitude on the GTX 327 screen as long as the G5 is powered on and configured properly with correct wiring.

GTX 327:

When you put the GTX 327 into configuration mode (power on while holding the FUNC key) was there a setting for pressure altitude display? I usually set it to "FEET" instead of the default of flight level "FLIGHT LVL". Then make sure the RS 232 INPUT is set to ICARUS ALT.

Also, in regular mode try pressing the "FUNC" button to scroll through the GTX display options.

G5:

The G5 configuration mode is entered by holding in the button while powering on.

Under RS 232 TX1 make sure it is set to "Altitude".

Wiring:

Make sure there is one twisted pair between the G5 and GTX for Signal and Signal Ground. Make sure the shield is drained at the backshell of each component.

Finally, if you have access to another GTX 327 you could slide it in and see if it exhibits the same behavior.
 
Thanks for the reply!


I had a harness made by the shop on the field, installed and configured as stated. I can not get it to work! ugh...

Only thing the avionics shop can come up with is maybe the GTX firmware is to old or the GTX doesn't work. They even took it off pin 19 and moved it to pin 2 (RS232 data) and nothing works. Rang it out to make sure the wires were to correct ins.

Nothing.... :(
 
Only thing the avionics shop can come up with is maybe the GTX firmware is to old or the GTX doesn't work. (

Ok, we give. What software is in your GTX 327?

GTX 327 V2.10 software was released in Feb. 2014 and is the latest software for all GTX 327 units manufactured before July 2014.

GTX 327 V2.12 software was released in July 2014 to support newer hardware in the GTX 327 units manufactured after that date.

GTX 327 V2.13 software was released in Aug. 2017 to address an altitude reporting issue only when using a Gillham based altitude encoder with GTX 327 (011-00490-00) serial numbers 83750922 to 83752847 or GTX 327 (011-00490-10) serial numbers 84000356 to 84000357.

Make sure your G5 unit is also using the latest software.

G5ToGTX327.png

Steve
 
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Ok, we give. What software is in your GTX 327?

GTX 327 V2.10 software was released in Feb. 2014 and is the latest software for all GTX 327 units manufactured before July 2014.

GTX 327 V2.12 software was released in July 2014 to support newer hardware in the GTX 327 units manufactured after that date.

GTX 327 V2.13 software was released in Aug. 2017 to address an altitude reporting issue only when using a Gillham based altitude encoder with GTX 327 (011-00490-00) serial numbers 83750922 to 83752847 or GTX 327 (011-00490-10) serial numbers 84000356 to 84000357.

Make sure your G5 unit is also using the latest software.

View attachment 6763

Steve

i believe it was the GTX 327 V2.12 version. I'll check the G5. On another note; I didn't understand why they switched to pin 2 to see if that would work. Was told it wouldn't matter but everything i read says pin 19 which is what they originally did.

Thanks for your time!
 
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Jay, I learned one thing about avionics install, be methodical...

Whilst my craft sports a slightly different config than yours, there must be similarities. My panel has dual G5s coupled to a GNX375. In the G5 installation manual, and your 327, you will find quite a few interconnect diagrams. I used those to final draw a version pertaining to my config, using only the necessary wires, see the attachment.

I guess Garmin tech reps still being on holidays, but I suggest contacting them directly at [email protected]
Usually very good and quick support.
 

Attachments

  • Interconnects.pdf
    443.4 KB · Views: 198
Thanks for the reply!


I had a harness made by the shop on the field, installed and configured as stated. I can not get it to work! ugh...

Only thing the avionics shop can come up with is maybe the GTX firmware is to old or the GTX doesn't work. They even took it off pin 19 and moved it to pin 2 (RS232 data) and nothing works. Rang it out to make sure the wires were to correct ins.

Nothing.... :(

Pin 2 should work in lieu of Pin 19, but make sure the GTX RS232 RX2 is set to ICARUS in the GTX Configuration Mode.

I have done this with half a dozen GTX 327's and have never had an issue with it. With various software versions.

Since you are working with an avionics shop, surely they have access to spare GTX 327 for a swap out test. The 327's are plentiful on most shop shelves since so many are switching to 1090 ES transponders. I still prefer the GTX 327 but that's because I like anonymous mode capability. Used 327's are fetching around $300 on the used market (I just checked Facebook classifieds).
 
But if I were a betting type I would bet there is a problem in the harness, configuration settings or pinning because it just doesn't make sense. If a GTX swap-out doesn't make it work then it could well be the G5. I have had two new G5's go haywire. One at 20 hours and the other out of the box. So try that swap too if able.
 
I had to do the following to get my GTX-327 to communicate with my G3X:
1. Update the 327 firmware. $40 at the avionics shop.
2. Go to the 327 configuration page. Change the RS232 INPUT and OUTPUT to REMOTE. The G3X manual only addressed the INPUT format.

It worked for me.
 
I had to do the following to get my GTX-327 to communicate with my G3X:
1. Update the 327 firmware. $40 at the avionics shop.
2. Go to the 327 configuration page. Change the RS232 INPUT and OUTPUT to REMOTE. The G3X manual only addressed the INPUT format.

It worked for me.

The OP shouldn't have to do that as we are talking about the G5 as an encoder. The OP doesn't have a G3X. What you describe is for thr G3X to allow remote control of the transponder which is a different thing all together.
 
Sorry for not updating in a while.

So I had the avionics shop who made the harness go back over everything and it still did not work! They rang out the wires to ensure proper location and even moved the pin 19 to pin 2 just to check in case 19 was bad. Nothing! They suggested I check it with another GTX 327 in case mine was bad. I Did that and still nothing!

Called Garmin and was told "maybe" its the G5 firmware as its about 6 updates behind. Did that today and tested with both of the GTX 327 and still nothing!

I decided to take out the harness and the "tray" for the GTX to personally inspect the wiring. In particular was it wired as the diagram shows and guess what, it was not! They had the pin 5 from the G5 going to the tray instead of pin 25 on the GTX. Then pin 25 wasn't grounded but just dangling. I was told there wasn't a need to connect the pin 25 to ground and it was fine to dangle.

I returned to the avionics shop and they said they didn't have time to look at it and that it was all ok! I decided I would head over to a friends friends avionics shop to have them look at it. They literally took one look and said the "signal" ground was incorrect and wired it as the diagram shows.

They are pretty confident it will work, we shall see!
 
stating the obvious here, every wire and pin has to be in its correct position. There are plenty of schematics in the G5 and the other Garmin LRU's. Important to pick the relevant ones and precisely follow the pin numbers...

Having now done several Garmin installs, I learned that the configuration is as important as the physical installation of the elements...

Fingers xed for yours!
 
Wow. I hope the first shop wasn't a Garmin dealer. That's avionics data bus 101 to wire serial signal wires per the manual.
 
Wow. I hope the first shop wasn't a Garmin dealer. That's avionics data bus 101 to wire serial signal wires per the manual.

It most definitely was! In addition they said they mimicked the RS232 feed into the GTX and that the GTX was bad.

***Update- I wired back in the harness and it still didn't work. Called the 2nd shop and they said they found a G5 to test the GTX with and to bring it back. I then pulled my G5 (just in case) and took everything back. They hooked it to the good G5 and it "worked"!! Yes.... Finally know the issue.

We will see if mine is in warranty and ship it back to be fixed Monday. Can't wait! Blue skies and no transponder sucks! I'm under a Bravo so need the Mode C.
 
G5 Software & Changes

Guys,

Can I throw in a related question but not directly related?
It seams that Garmin has new Software for the G5's that will allow direct connection between a HandHeld GPS, in this case a Garmin 295. Which runs NMEA 0183 at 4800 Baud. The old G5 software would not connect with NMEA and it also wanted 9600 Baud.
Am I correct on these statements?
Thanks gang, AND if I am in the wrong forum would you post the correct one?

Barry
 
Guys,

Can I throw in a related question but not directly related?
It seams that Garmin has new Software for the G5's that will allow direct connection between a HandHeld GPS, in this case a Garmin 295. Which runs NMEA 0183 at 4800 Baud. The old G5 software would not connect with NMEA and it also wanted 9600 Baud.
Am I correct on these statements?
Thanks gang, AND if I am in the wrong forum would you post the correct one?

Barry

Try contacting G3xpert, who you can find on this forum (search). I’m sure he can answer your question.
 
Yes. You should see pressure altitude on the GTX 327 screen as long as the G5 is powered on and configured properly with correct wiring.

GTX 327:

When you put the GTX 327 into configuration mode (power on while holding the FUNC key) was there a setting for pressure altitude display? I usually set it to "FEET" instead of the default of flight level "FLIGHT LVL". Then make sure the RS 232 INPUT is set to ICARUS ALT.

Also, in regular mode try pressing the "FUNC" button to scroll through the GTX display options.

G5:

The G5 configuration mode is entered by holding in the button while powering on.

Under RS 232 TX1 make sure it is set to "Altitude".

Wiring:

Make sure there is one twisted pair between the G5 and GTX for Signal and Signal Ground. Make sure the shield is drained at the backshell of each component.

Finally, if you have access to another GTX 327 you could slide it in and see if it exhibits the same behavior.


would the above configuration Settings and pin assignment
apply to Garmin GTX330ES as well.

I appreciate the info.:)
 
I don't know. All I ever deal with is Mode C transponders but there shouldn't be any reason you can't hook a G5 to a GTX 330ES the same way. But you will want to get a copy of the pin outs or manual for the GTX 330ES to find out which pins are for RS 232 "in".
 
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