Garmin GTX327 / 430 / GRT

Hi,

I'm stuggling with getting my head round some of the avionics wiring. I've already studied the GRT wiring layouts and the Garmin installation manuals etc. I have a Stark harness as a starting point.

Specific question: The Stark harness has an Fuel/Air data RS232 input to the 327 (Txpndr), in addition it also has RS232 In / Out pair coupled to the 430. Does the 327 'forward' the fuel air data over its direct link to the 430?

The GRT 'way' is for the MFD to provide Fuel/Air to both the 430 and 327 directly.

Any insight / reasons / pros / cons.

Cheers, Carl

Hi Carl,

I did it the GRT way and it works well if that's any help.

The Garmin units do exchange the RS232 data but you certainly want that
RS232 feed going to the EFIS as well. You can always tap the RS232 feed.
I left a couple of additional lines tapped and unconnected in case I needed
to change something down the road.

zkvii said:

Specific question: The Stark harness has an Fuel/Air data RS232 input to the 327 (Txpndr), in addition it also has RS232 In / Out pair coupled to the 430. Does the 327 'forward' the fuel air data over its direct link to the 430?

The GRT 'way' is for the MFD to provide Fuel/Air to both the 430 and 327 directly.

Any insight / reasons / pros / cons.

Click to expand...

If I understand you query correctly, the connection will be as follows:

GRT-->GTX-327<-->GNS-430

If the 327 is bad or missing, altitude will NOT be provided to the Garmin 430. Also, the GTX-327 will NOT send anything other than altitude information to the 430 if wired this way--unless the GRT can emulate a shadin-adc.

A alternative method may be to have the GRT feed the 327 and 430 in parallel. That way GPS altitude is not dependant on the GTX-327. Much simpler to trouble shoot and eliminates device dependency.

GRT-->GTX-327 (Altitude information for RAIM)
GRT-->GNS-430-->GTX-327 (allows automatic STBY/ALT switching)

Air/Data (Serial Altitude) from GRT to GTX-327 pin 19
Air/Data (Serial Altitude) from GRT to GNS-430 serial in
Aviation Data from GNS-430 to GTX-327 pin 2

Hi,

Thanks guys - that is what I was thinking - but nice to have it confirmed. I'll go with GRT to both GTX and GNS.

I decided to just break out the avionics feeds to a seperate DB25 that everything else can then be patched into... Also found the documentation that allow the GTX output to be switched off if needed. I won't change the stark harness further, just add to the 2,3,4 feeds. Looks like it is going to work well.

Final question - anybody know what the VOR/ILS ARINC 429 Input is used for on the 430 - doesn't get used anywhere - I'm just curious.

Thanks, Carl

zkvii said:

Final question - anybody know what the VOR/ILS ARINC 429 Input is used for on the 430 - doesn't get used anywhere - I'm just curious.

Thanks, Carl

Click to expand...

Carl,

I've been asking myself that question for a year or more Carl. I thought it was so that you could provide OBS data "FROM" the GRT DU "TO" the 430, but I could never get any bits to transfer across it (430 said it got nothing). However, the OBS function on the GRT works just fine, so I quit worrying about it. I think I asked Todd or Mark about last year, and the slightly puzzled response was that they weren't sure what was intended, but whatever it was, the code hadn't been written yet....

Paul