Garmin Power Data Cable

[avi8tor50]

For those of you with 396/496 who have connected the power data cable:

Need to connect my GPS to TT autopilot and EFIS. I see that there are two ports out on power data cable. Can these be connected to the TT and EFIS? Does it make a difference which goes to which? Where do voice (+) and voice (-) connect? Where does white connect?
Could not find any documentation from Garmin for the violet wire which is the second port out.
Thanks for input.

Peter K
9A

[KPmarc]

Don't use the voice connections. I believe you want the blue wire, which is the RS-232 output. You can connect it directly to the TruTrak and the EFIS serial input. The yellow wire is data in, in case you have a GTX-330 transponder and want to get traffic. (Or the new Zaon.)

Garmin has a user's manual online. It shows the power/data cable schematic on Page 158.

--Marc

[ccarter]

I'm confronted with the same issue. There is a violet wire labeled Port Out 2 on the 496 wire harness. The blue wire (labeled Port Out 1) is feeding the Rx of my SL-30. I'm hoping the violet wire has serial data on it. I need it to drive another "gizmo" on my panel. I definately want my TT to fly waypoints from the 496.

[RV7Guy]

Marc has is correct. The voice wires are for the automotive purposes and he outlines the proper hook up for the AP and 232 line.

Use the stereo jack for your audio. Unfortunately, the unit doesn't come with this stereo jack. This provides with L/R and Lo. Tie this into your audio panel "music" or intercom system.

Originally Posted by KPmarc

Don't use the voice connections. I believe you want the blue wire, which is the RS-232 output. You can connect it directly to the TruTrak and the EFIS serial input. The yellow wire is data in, in case you have a GTX-330 transponder and want to get traffic. (Or the new Zaon.)

Garmin has a user's manual online. It shows the power/data cable schematic on Page 158.

--Marc

[hevansrv7a]

Originally Posted by avi8tor50

...Need to connect my GPS to TT autopilot and EFIS. I see that there are two ports out on power data cable. Can these be connected to the TT and EFIS? Does it make a difference which goes to which? Where do voice (+) and voice (-) connect? Where does white connect?
Could not find any documentation from Garmin for the violet wire which is the second port out.
Thanks for input.

Peter K
9A

The "gotcha" in all this is that for the EFIS (mine is GRT) and the TT, you need NMEA OUT on the Garmin. What is not well documented is that you cannot configure Com1 and Com2 the same way; the Garmin will not do it. I confirmed this with their Tech Suppt. Also, for GRT EFIS, you will want to use NMEA IN/NMEA OUT with Baud=4800 (not a choice on the Baud). This will work fine for GRT and TT. You can branch the Com1 wire up to three destinations without a problem. For another EFIS, one of the other in/out settings might work; I don't know. In any case, the Baud settings for output from Garmin and input on EFIS and TT must agree. Although you'd think 9600 would be better than 4800, I see no degradation with 4800 and in fact, it works more reliably.

For EFIS such as GRT, there is an advantage to connecting the Garmin to EFIS and EFIS to TT. That advantage is being able to fly VOR/LOC/ILS course from GPS course seamlesly such as for an approach. GPSS needed to do this well, but it will do it with only GPS Nav. As backup, I wired the Com1 to both the EFIS and the TT and the EFIS to the TT. This of course required a selector for the TT's source of info.Feel free to contact me via mail or PM for more details.

Sorry, I have no information about voice; I don't use it; I can hear the Garmin's alerts well enough even over the engine/prop noise (using HALO).

[ccarter]

hevansrv7a,

That is very helpful thx. There are actually 9 wires coming out of the 496 power data cable, 5 in the center of the connector and 4 on the perifery. Two on the perifery are not labled in the manual diagram. One is violet labled PORT OUT 2 the other is green PORT IN 2. It makes sense that configuring the serial data stream using the 496 interface configures both ports, meaning the serial ports are not independantly configureable. What you get with one is what you get with the other. Did Garmin tech support confirm there is in fact serial data on port 2? I don't have an O-Scope to confirm this. My concern is loading port 1 down by connecting multiple devices to it. RS232 is a hearty signal and can probably tolerate splitting in the way you describe however. Did you crimp several small wires to the Garmin blue data out to grab the signal? If there is the same data on the violet wire I would prefer to use both.

[hevansrv7a]

Originally Posted by ccarter

hevansrv7a,

That is very helpful thx. There are actually 9 wires coming out of the 496 power data cable, 5 in the center of the connector and 4 on the perifery. Two on the perifery are not labled in the manual diagram. One is violet labled PORT OUT 2 the other is green PORT IN 2. It makes sense that configuring the serial data stream using the 496 interface configures both ports, meaning the serial ports are not independantly configureable. What you get with one is what you get with the other. Did Garmin tech support confirm there is in fact serial data on port 2? I don't have an O-Scope to confirm this. My concern is loading port 1 down by connecting multiple devices to it. RS232 is a hearty signal and can probably tolerate splitting in the way you describe however. Did you crimp several small wires to the Garmin blue data out to grab the signal? If there is the same data on the violet wire I would prefer to use both.

I need to clarify this (see underlining added above). You can configure Com1 and Com2 independently. What you cannot do is configure them the same. Two ports, two different settings. Therefore if you want two serial outputs in the identical format you must use the Com1 OR the Com2 wire and split/branch it. Both Com out ports do output serial data in various formats and speeds.

The wires are very fine. I just used a (red) barrel crimp, input on one side and join them inside the output side and covered it with shrink tube. I think I had to double or triple-over the input wire to get it thick enough for a good crimp.

The 496 configures each of the two Com ports as a specific combination of in and out. I've only been using the (NMEA) out. You could, for example, have it talk 2-way with an SL-30. I don't do that because my EFIS needs to handle the SL-30. And, of course, there are depth finders and fish finders and other weird things. My 496's XM weather has its own special connector so that's not affected by all this. Later I will probably use the other Com port (in) for traffic from a Zaon. I also don't use the audio, but it's there. Garmin's tech support person on the telephone was very helpful and patient. It's a shame their documentation isn't better.

However, this may help:
http://www8.garmin.com/support/faqs/faq.jsp?faq=68

I hope this is helpful. I'll keep yakking until it is.

[mburch]

Hi all,

The "#2" wires in the cable are unused for the 396 and 496, because both those units have only one comm port (#1). The 296 does have two comm ports, and I guess Garmin saves a few pennies by reusing the same cable across all the different models.

mcb

[N941WR]

Check out this thread:

http://www.vansairforce.com/communit...ad.php?t=14479