Re: question about can bus

Hello
Jean-Francois

Am Montag 08 April 2013, 11:05:17 schrieb Lacassaigne Jean-Francois:
> Hi,
> Greetings from Belgium.
> 
> I'm working on a data bus who use right now only the physical layer of the 
> can bus. (tranceiver only and no controller).
> This works as there is only one device talking on the bus. all other are 
> "listen only".

This sounds strange to me. A CAN transceiver alone does nothing on the bus.
It always depends what the signal at the TX input are. So to say the controller,
whether it is a CAN controller or any other device, determines the signal on the bus.
In any case it is 'dominant' or 'recessive'.
If one device should be in 'listen only',
it has to ensure it drives the bus level always to 'recessive'

> My question is as follow :
> If i add can controller only to the "talking devices", will the "listen 
> only" devices still be able to get the message even without having a can 
> controller on board.
Yes, but ensure that the TX input is 'High',
which drives the transceiver output to 'recessive'.
> 
> this would give a bus with :
> * talking devices having can bus controller and can bus transceiver
> * listen only devices having only can bus transceiver.
> 
> 
> kinds regards
> 
> jean-francois 

I hope this will help a bit.

Kees answer regarding real CAN controller nodes is true,
but not the following:

Am Montag 08 April 2013, 11:44:09 schrieb Kees Zagers:
> So your statement: "* listen only devices having only can bus transceiver." is NOT TRUE.

See above. You can use the CAN transceiver only in receive mode
if you don't use the TX input.

Regards
    Heinz


--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector.com/canlist/
Report any problems to <[email protected]>