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  #11  
Old 09-11-2018, 10:10 PM
Bavafa Bavafa is offline
 
Join Date: Oct 2007
Location: Sacramento, CA
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Quote:
Originally Posted by bkervaski View Post
Most of us install in the Vans' specified location without any problems.

I had a bad GMU11 and that caused some grief, I couldn't get it to calibrate. Once I got a replacement, it calibrated easily the first time and has worked flawlessly.

Edit: SteinAir/Garmin replaced it for me without any hassle, thanks again to both
Are you referring to the bracket in the second bay in the left wing? is there an easy way of mounting a GMU11 in that bracket and any issues?
I have read that the wing tip gets better results.
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  #12  
Old 09-11-2018, 10:36 PM
n982sx n982sx is offline
 
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Location: Chicago, IL
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Quote:
Originally Posted by rocketman1988 View Post
We talked awhile and it was brought to light that the GMU communicates via the CAN bus. Normally not a problem in the RV aircraft, however, there is a LIMIT on the total length of the CAN bus.
There are different types of length limits to CAN, overall length and stub length are the two we are concerned with. There is no reason we need long stub lengths (Garmin wants them under .3m) and overall length is not a problem in any RV. Overall bus length is limited to 20 meters at the high bit rates we use.

At those lengths you could start the linear backbone bus at one end of the left wing, go all the way to the end of the right wing, come back and go all the way to the tail with any RV. Which would also be unnecessary with any RV.
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Last edited by n982sx : 09-15-2018 at 10:34 PM. Reason: Edited CAN bus max length
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  #13  
Old 09-12-2018, 12:16 AM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 2,189
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So I guess the guys that are doing tons of RV setups don't know what they are talking about...

From the Install manual:

"2.3.1.3.5 CAN Bus Installation Guidelines
For maximum reliability of the CAN bus, the following guidelines should be followed:
• The CAN bus backbone must be a single linear path with exactly two distinct ends. CAN bus
connections should be “daisy chained” from device to device. Avoid “star” and “Y” topologies,
and do not use a hub device (see Figure 2-12).
• The overall length of the bus should not exceed 20 meters (66 feet).
• Keep all stub node connections as short as practical. The maximum length of any stub node
connection is 0.3 meters (1 foot)."


I think I will stick with the guys that are doing this for a living...YMMV
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Last edited by rocketman1988 : 09-12-2018 at 12:32 AM. Reason: content
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  #14  
Old 09-12-2018, 11:32 AM
snoop9erdog snoop9erdog is offline
 
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Posts: 259
Default Can Bus

A 10 might indeed require more length and I can't imagine the other models would require more.....but in my 9 I don't need to worry about a yaw dampener, so mine will likely start in the right wing with the GMU11 and end at the pitch servo just behind the baggage bulkhead, forming a wide U shape. Probably around 40 ft. This is what the G3X class recently recommended. Wonder if it can be configured similarly in the 10 or if the yaw dampener servo creates an issue for the length? It must.

Rocket man has the guidelines right on. The biggest things emphasized to us was to keep the bus linear and daisy chained and the node lengths shorter than a foot.
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  #15  
Old 09-12-2018, 11:48 AM
rocketman1988 rocketman1988 is offline
 
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Location: Sunman, IN
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Default Gmu

...which is why Steiner recommends the gmu22 for the -10. It doesn?t use the CAN bus, so it doesn?t add to the length...
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Aerospace Engineer '88

RV-10
Structure - 90% Done
Cabin Top - Aaarrghhh...
EFII System 32 - Done
297 HP Barrett Hung
ShowPlanes Cowl with Skybolts Fitted - Beautiful
Wiring...

Dues+ Paid 2019,...Thanks DR+
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  #16  
Old 09-12-2018, 11:49 AM
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kbalch kbalch is offline
 
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I was advised (by one of Stein's guys) to place the GMU22 in the -14's left wing ADAHRS mount and that's how I've configured my just-completed wing.

Why go with the GMU11 at all? What am I missing?
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  #17  
Old 09-12-2018, 01:36 PM
Icarus Icarus is offline
 
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Location: D.C.
Posts: 303
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Quote:
Originally Posted by rocketman1988 View Post
So I guess the guys that are doing tons of RV setups don't know what they are talking about...

From the Install manual:

"2.3.1.3.5 CAN Bus Installation Guidelines
For maximum reliability of the CAN bus, the following guidelines should be followed:
• The CAN bus backbone must be a single linear path with exactly two distinct ends. CAN bus
connections should be “daisy chained” from device to device. Avoid “star” and “Y” topologies,
and do not use a hub device (see Figure 2-12).
• The overall length of the bus should not exceed 20 meters (66 feet).
• Keep all stub node connections as short as practical. The maximum length of any stub node
connection is 0.3 meters (1 foot)."


I think I will stick with the guys that are doing this for a living...YMMV
With a total length AND span summed to around ~56 feet, it would take the world's most schizophrenic wire run to bust your quoted total length. Just wire it, the largest source of signal loss is going to be poor technique not the length (in supplied scenario).

-Guy with nominal signal loss in setup who apparently doesn't know what he's talking about.
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Last edited by Icarus : 09-12-2018 at 01:40 PM.
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  #18  
Old 09-12-2018, 02:37 PM
AviatorJ AviatorJ is offline
 
Join Date: Feb 2015
Location: Oklahoma City
Posts: 913
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Quote:
Originally Posted by rocketman1988 View Post
...which is why Steiner recommends the gmu22 for the -10. It doesn’t use the CAN bus, so it doesn’t add to the length...
Guess that depends who you talk to, and what your setup is. It was suggested to me to go with the GMU11. They did the harness as well and kept it down to 40' I beleive.

Quote:
Originally Posted by kbalch View Post
Why go with the GMU11 at all? What am I missing?
What I was told because it communicates on the CAN bus and I have a full Garmin layout that both G3X's and my G5t and whatever else needs it will retrieve the information.

I struggled a bit with where to mount it as well. After reading installation guidance and seeing what a few others did I decided to make essentially a tiny shelf hanging off a aluminium angle. I'm still debating how to fasten it onto the longeron. I'm hesitant to drill into the longeron so will either use some two-sided tape or my go to 3M adhesive which seems to lock anything I use it on in place. Took a few pictures prior to primer.

Here's one pre-trim. I ended up smoothing out the edges and making the front even.



Here it is just sitting in place. It's a snug fit.
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  #19  
Old 09-12-2018, 02:42 PM
rocketman1988 rocketman1988 is offline
 
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Location: Sunman, IN
Posts: 2,189
Default Setup

What setup did you go with?
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Aerospace Engineer '88

RV-10
Structure - 90% Done
Cabin Top - Aaarrghhh...
EFII System 32 - Done
297 HP Barrett Hung
ShowPlanes Cowl with Skybolts Fitted - Beautiful
Wiring...

Dues+ Paid 2019,...Thanks DR+
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  #20  
Old 09-12-2018, 02:53 PM
AviatorJ AviatorJ is offline
 
Join Date: Feb 2015
Location: Oklahoma City
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Outside of the VPX, CO2 detector and a few random things everything else is Garmin. I have Dual G3X's, the 245 audio panel, the 507 AP head, GTN 650, Remote comm, remote transponder with ADS-B in/out, G5, their ARINC box and Engine monitoring system. I essentially never wanted any compatibility issues.
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