Matronics Email Lists Forum Index Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

CAN BUS

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List
View previous topic :: View next topic  
Author Message
user9253



Joined: 28 Mar 2008
Posts: 1436
Location: Riley TWP Michigan

PostPosted: Wed Sep 04, 2019 6:26 am    Post subject: CAN BUS Reply with quote

The Rotax 912iS engine outputs engine parameter data via CAN Bus A and
via CAN Bus B. The SkyView System Installation Guide - Revision AE
https://www.dynonavionics.com/includes/guides/SkyView_System_Installation_Guide-Rev_AE_v15_4.pdf
on page 7-37 has a wiring diagram showing SV-EMS-
221 pins 36 and 37 connected to both CAN Bus A and CAN Bus B wired in
parallel. I know nothing about a CAN Bus. But it seems to me that if Rotax
had intended for both CAN Buses to be connected in parallel, that they would
have provided only one CAN Bus instead of two. Can someone explain why it
is OK to connect the two Rotax CAN Buses in parallel? Thanks


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Joe Gores
Back to top
View user's profile Send private message
gilles(at)elixir-aircraft
Guest





PostPosted: Wed Sep 04, 2019 7:10 am    Post subject: CAN BUS Reply with quote

Le 04/09/2019 à 16:26, user9253 a écrit :
Quote:

and 37 connected to both CAN Bus A and CAN Bus B wired in
parallel. I know nothing about a CAN Bus. But it seems to me that if Rotax
had intended for both CAN Buses to be connected in parallel, that they would
have provided only one CAN Bus instead of two. Can someone explain why it
is OK to connect the two Rotax CAN Buses in parallel? Thanks

Joe and all,


Two years ago I had the opportunity to design the wiring for a 912iS
equipped aircraft.
Here is what I was told by a person having participated in the design of
the Rotax Can Bus system :

- Rotax did not design their CAN Bus systems, but outsourced the design.

- At the beginning Rotax advised it was OK to connect both CAN Buses, so
Garmin and other avionics manufacturers chose this path.

- Somewhere along the line Rotax was instructed about the disadvantages
of connecting both buses, and so changed its installation instructions.

- Garmin and other manufacturers didn't change the desing of their
products, keeping the both-connected approach.

FWIW,
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
nuckolls.bob(at)aeroelect
Guest





PostPosted: Wed Sep 04, 2019 7:43 am    Post subject: CAN BUS Reply with quote

Quote:
Can someone explain why it
is OK to connect the two Rotax CAN Buses in parallel? Thanks

--------
Joe Gores

The CAN bus has been around for a very
long time. See:

https://tinyurl.com/lc2mygs

Originally crafted for the automotive
world, it has proven to offer great
utility just about everywhere lots
of electro-whizzies need to talk to
each other on a 'party line' bus.

Not all CAN busses are the same.
Each whizzy needs to be 'educated' as
to the protocol for transmitting and
receiving messages/data while behaving
in a neighborly fashion with respect
to 'collisions' on the bus.

So the idea that two otherwise independent
CAN systems can be tied together is
not far fetched as long as every
whizzy on BOTH busses share the same
messaging protocols.

For example, you might purchase an
oil pressure instrument originally
intended for service in a over-the-road
truck with an expectation that it
would accurately display oil pressure
on your engine.

Yeah . . . maybe . . . assuming the bus
messaging protocols are the same. Then
there are risks that more than one 'talker'
with the same message i.d. would
promulgate confusion amongst 'listeners'
having an interest in those messages.

Proceed with caution.


Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
glastar(at)gmx.net
Guest





PostPosted: Wed Sep 04, 2019 7:53 am    Post subject: CAN BUS Reply with quote

Hi Joe,

the 912iS has two ECU's each of em having its own CAN  connection. Now
as the Dynon EMS 221 has only one CAN Bus interface you need to hook up
both in parallel, the CAN Bus "packet ID" will tell which ECU it's
coming from as it is a "broadcast" protocol all packets should arrive at
the 221, if you want to have more redundancy you might be able to hook
up two EMS 221 in order to have both ECU's on different engine boxes
(check with Dynon).

As it is a bus it will work with one EMS only.

Hope it helps a bit to understand.

Cheers Werner

On 04.09.2019 16:26, user9253 wrote:
Quote:


The Rotax 912iS engine outputs engine parameter data via CAN Bus A and
via CAN Bus B. The SkyView System Installation Guide - Revision AE
https://www.dynonavionics.com/includes/guides/SkyView_HDX_Pilots_User_Guide-Rev_D_v15_4.pdf
on page 7-37 has a wiring diagram showing SV-EMS-
221 pins 36 and 37 connected to both CAN Bus A and CAN Bus B wired in
parallel. I know nothing about a CAN Bus. But it seems to me that if Rotax
had intended for both CAN Buses to be connected in parallel, that they would
have provided only one CAN Bus instead of two. Can someone explain why it
is OK to connect the two Rotax CAN Buses in parallel? Thanks

--------
Joe Gores


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=491184#491184




- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group