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GPS-175 to G5 Experimental question

prkaye

Well Known Member
Hi all
Avionics wiring newbie here with two questions about GPS-175 & G5:

1) I'm looking for confirmation that i can connect a GPS-175 directly to the G5 Experimental (single RS-232 connection) to allow the G5 to be used as an HSI display for the GPA-175. WIll a direct connection work, or do i need some auxiliary interface like a GAD-29?

2) It looks to me that it would be a one-way RS-232 connection, connecting the RS-232 OUT of the GPS-175 to the RS-232 IN of the G5 (and also connecting the signal ground between the two units). Assuming this is correct, do i just leave other two signal pins (RS-232 IN on the GPS and OUT on the G5) completely unconnected on the wiring harness?

3) Is this really all that's needed? Two wires between the two units (plus aircraft power and ground for each unit)?
 
Hi all
Avionics wiring newbie here with two questions about GPS-175 & G5:

1) I'm looking for confirmation that i can connect a GPS-175 directly to the G5 Experimental (single RS-232 connection) to allow the G5 to be used as an HSI display for the GPA-175. WIll a direct connection work, or do i need some auxiliary interface like a GAD-29?

2) It looks to me that it would be a one-way RS-232 connection, connecting the RS-232 OUT of the GPS-175 to the RS-232 IN of the G5 (and also connecting the signal ground between the two units). Assuming this is correct, do i just leave other two signal pins (RS-232 IN on the GPS and OUT on the G5) completely unconnected on the wiring harness?

3) Is this really all that's needed? Two wires between the two units (plus aircraft power and ground for each unit)?
Phil,

As a minimum, to install a G5 HSI with a GPS 175 (or GNC 355, GNX 375, GTN), you would need to add the GAD 29 ARINC 429 interface.

G5 HSI GNX375_GMU11_GAD13.png

Optionally, you could add the GMU 11 magnetometer (to use heading instead of GPS track on the HSI).

You could also optionally add a GAD 13 with OAT probe which is used in combination with the GMU 11 to support the display of winds aloft on the G5 HSI.

It is a good idea to add the MapMX RS-232 interface from the GPS 175 to the G5 to give the G5 another high quality GPS source.

Steve
 
Ok thanks Steve. Let me back-up. I was sort of assuming i would need some kind of CDI/HSI to be able to get the full functionality of the GPS-175. I haven't started IFR training yet, so my understanding of this stuff is rudimentary.
Question - does the GPS-175 built-in display give me everything i need to fly RNAV GPS approaches? What would be the practical limitations of using hte GPS-175 as a stand-alone without connecting it to an extrnal HSI?
 
Phil,

As a minimum, to install a G5 HSI with a GPS 175 (or GNC 355, GNX 375, GTN), you would need to add the GAD 29 ARINC 429 interface.

View attachment 26649

Optionally, you could add the GMU 11 magnetometer (to use heading instead of GPS track on the HSI).

You could also optionally add a GAD 13 with OAT probe which is used in combination with the GMU 11 to support the display of winds aloft on the G5 HSI.

It is a good idea to add the MapMX RS-232 interface from the GPS 175 to the G5 to give the G5 another high quality GPS source.

Steve

Steve hit the nail on the head.

When I researched what I needed to add the GPS unit to my G5 installation, I needed to add the Garmin ARINC box to make the HSI work.
 
Ok thanks Steve. Let me back-up. I was sort of assuming i would need some kind of CDI/HSI to be able to get the full functionality of the GPS-175. I haven't started IFR training yet, so my understanding of this stuff is rudimentary.
Question - does the GPS-175 built-in display give me everything i need to fly RNAV GPS approaches? What would be the practical limitations of using hte GPS-175 as a stand-alone without connecting it to an extrnal HSI?

Phil,

Your first assumption was correct.

The GPS 175 provides no display of lateral/vertical deviation, but does provide this information to external devices/systems like the G5.

You wouldn't really be able to fly an RNAV GPS approach (especially the glidepath) without an external display like the G5.

The G5 system is very expandable should you choose to do so.

DualG5_Aera760_GAD13_GMU11_GMC507_GSA28arm_GNX375_16May2022.jpg

Steve
 
From the pilots guide... isn't this "CDI On Screen" providing lateral deviation guidance? Am i misunderstanding something?
 
Lateral guidance

I actually tried to set this up by just rs-232. It works for basic gps vfr function but it will not give you any approach info including lateral. It shows up as a totally different mode on the hsi as well. Also, you may need to use the can bus wiring to get the full Ifr capability.
 
Ok thanks guys. I've come to realize this wiring is goign to be a lot more complicated and time-consuming than i thought. So I'm going to get Stein to pre-wire it all for me instead :)
Thanks for the helpful explanations! I would have been cursing if i had discovered all of these factors the hard way!
 
From the pilots guide... isn't this "CDI On Screen" providing lateral deviation guidance? Am i misunderstanding something?

Yes, it does have lateral guidance, but definitely no vertical guidance. One's not much good without the other and you can't fly an approach without a another device to display that guidance.
 
Ok thanks guys. I've come to realize this wiring is goign to be a lot more complicated and time-consuming than i thought. So I'm going to get Stein to pre-wire it all for me instead :)
Thanks for the helpful explanations! I would have been cursing if i had discovered all of these factors the hard way!

If you still want the pleasure of wiring, Stein can make you an interconnect drawing. This will take all the mystery out of how to connect everything.
 
It's not hard to wire, I did it without any experience in aircraft wiring, I just read the manual.

To answer the questions, no you can't fly an approach without some sort of CDI, that can be the G5 or the dynon brand. It can also do some older ones as well. Plenty of options.

If you only wire the serial data to your G5 you will get a VFR only message, instead of Enroute, Terminal, LNAV/VNAV/LPV depending on the approach and what WAAS precision is available at the time.

You will need a GAD29. This is the only way to get ARINC data from the navigator to your G5 or other CDI/HSI. You don't need the temp gauge, although it will give you winds if you have it. You also will need a Magnetometer. All of these are also wired on the Garmin's canbus network. They all talk to each via the Canbus (minus ARINC 429 data streams). The G5 is the only way for you to configure all of these items to talk to each other (unless you are using the garmin G3x system). There is more to this but the basics are covered in this post. The install manual will show you way more.
 
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