Dinho wrote:
> Hi,
>
> I'm facing some problems with CAN Bus. first of all I'd like to know
> where can I find more information about CAN?
>
> Second, let me explain what's happening. I'm developing my first CAN
> node. I have made a program that gets some information from serial port
> and send it through CAN bus. I'm using a PIC18F248 and a MCP2551
> transceiver. I have made 2 nodes exactly the same.What I could verify was:
>
> If I put my module in loopback mode, I can see at RX buffer everything I
> put in TX buffer.
> In normal mode, using a scope, I can see that CANRX receive everything I
> put in CANTX (PIC side)
> still in normal mode I can see at the CAN Bus line the same information
> I have at CANTX, but at the other node (after the transiver) I have
> nothing in CANRX.
>
> Could someone explain me what's happening and (if) what I'm doing wrong?

I used to have that problem a lot when I first stated with CAN. Can't
remember what all caused it, seemed like most anything would cause that
behavior. At one point I had an extrememly fine solder bridge across TX
and RX that I could only see with a microscope. That messed everything
up. I also found that with short line lengths (~6") termination actually
made things worse. Check your software very carefully, and go over the
errata sheet. Sorry I'm not much help, maybe ill remember more in the
morning.

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