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Can-Bus Interface(explain)

10145 Views 10 Replies 3 Participants Last post by  Dec
Hi Guys,
Just Purchased RNS-E unit for my A4,could someone explain what is the difference between the can bus interface and the standard interface that goes with the RNS-E Unit?what does can-bus actually do???
Many Many Thanks
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I'm not sure I understand your question, but here's a simple explanation.

In the old days, pre 2001, cars were hard wired for all the signals, lighting, ignition, speed pulse etc all on seperate wires to devices in the car such as radios etc. So when you turned the key +12v triggered the device to power on or do whatever it needed to do, switch the lights on and another +12v says, hey the lights are on and the radio turns its lights on.

As electronics advanced in cars it was simpler to send information about the car around on a bus (2 wires) containing all the information and each device could pick off what it needed with simple chips that read the can bus.

So the RNS-E uses the infotainment canbus to receive and send information to and from the car, it receives ignition, lighting, speed etc over can and sends radio station info, nav info to teh cluster etc and controls devices over can such as the TV tuner and telephone interface.

The telephone interface sends information to the cluster and the RNS-E over canbus too.

If your RNS-E cannot see the infotainment canbus, it goes to sleep after 30 mins

most cars have multiple buses for different systems, engine management, entertainment systems and comfort systems.

Hope that helps
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Thanks for that,its extremely helpful,i should explain myself better,i have purchased RNS-E Unit without adaptors,i went on line and purchased the correct adaptor for my car(non bose,cd player etc havent recieved it yet)so i presuming all is ok,then i was browsing ebay and i seen an adaptor for sale described as can bus adaptor lead for RNS-E,So i was thinking maybe i have purchaed the wrong lead?,the lead i have purchased will work fine but will i get cluster display etc etc for the nav with the lead i have bought or would i need to purchase the one that has the can bus controller(the only difference i can see between the lead i have bought is a little grey box that say can bus for RNS-E on it),hope all that makes sense to you
If your A4 is an 8E/B6 or B7 then you don't need the CAN interface adapter (assuming you bought an 8E0 RNS-E unit). If you have the older A4 8D/B5 (model year 2000 or earlier) then you may need the CAN interface adapter.

The A4 8D/B5 started to get CAN during the MY 2000 but it depends on the option packages if you have CAN and it's sometimes difficult to find the right wires. The A4 8E/B6 had CAN since it's introduction in 2001 (Europe) or 2002 (North America).
Music to my ears,thanks for that,my car is 2002 B6 Model so im sorted/thanks for the help guys,when i seen the other adaptor i panicked,thanks for the info,now for the removal of my RNS-D,thats another story,again many thanks for taking the time to reply,im in europe(Dublin) btw,so im right in presuming that its more or less plug and play??we dont have tmc here either,will this cause probs do you guys think,i was able(with the help of RNS-D forum)to get the settings etc changed on my car(vag)so the error message(tmc error blah blah)stopped coming up,will i have a similar prob with RNS-E UNIT?.When i say we dont have TMC here i in mean,Ireland,its not set up like the Uk etc,
How did you install the RNS-D? Or did it come from the factory this way?
no did the install with a frirend of mine based on the info here and on the other vav plus site,i did a lot of redaing and then made him do all the work .)anyway it was working fine all good with it until recently i picked up a problem and could not resolve it,somebody suggested re-writing software to the unit,but the level of software in my unit is may 2005 and the higgest i could find on the web for downlaod was nov 2001 so i felt best not to try that,
If you didn't cut / change any wires when you installed the RNS-D then you can simply remove it, get the correct RNS-E adapter for whatever head unit you had before and install the RNS-E. If you did change the wiring when you installed the RNS-D and did a good and clean job, you could get the RNS-D to RNS-E adapter to plug and play install your RNS-E. In any case, the RNS-E doesn't need a TMC, if you have one installed remove it.
Thanks for that,yes i think we did a good job on it,the main prob we found was getting the rns-d to turn of from ignition,when we 1st installed that did not happen,i was having to turn the power switch manually on/off eventually after a lot reading we found the corrrect wire and wired it to the ignition,bingo it worked fine,i supose like all things you learn as you go along,the one thing i found out was Audi dealers here are useless and i mean useless,they havent a clue,anyways it all worked out in the end,the only thing we could figure out was for the sat nav info to come up in the DIS screen(cluster)hopefully when i connect up the RNS-E we wont have the same problem,if we do il cry lol,i purchased my adaptor from Kuftec in Germany,my car is non bose,and i asked for a cd connection also,fone connection etc,but i noticed that there lead has 3 connections on the end of it,i presume one is for cd,one is for fone but whats the 3rd one for??i have also bought a dvd player with adaptors aswell from Germany so im hoping the 3rd connection will do this or does this unit(dvd player)just connect into the video out on the rns-e unit??also with the dvd player where does it get power from,do i have to find a 12v supply for it,hope that makes sense to you,
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The third plug is for power, k-line and some other signals. The video interface connects to the 32pin AMP connector in the RNS-E and not to the RNS-E adapter.
Thanks again for the help,il keep you posted on my developments fingers croseed it all goes to plan,
Best wishes
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