Bus arbitration on CAN bus

Question

Hello I have a question concerning communication/arbitration on a CAN bus.

Say more than one masters on the CAN bus want to send simultaneously which means that the one with the lowest message identifier will win arbitration in the end and starts to send his payload. The others lose arbitration, switch to receiving mode and wait that the bus is free again.

Now my question:

Do the masters that lost arbitration in the previous try immediately arbitrate the bus again (i.e. when the bus is free)? Do they wait for their next activation cycle as defined in the CAN matrix? Or can that be defined in the CAN matrix individually?

Thanks in advance, Florian

Answer 1

I don't know what you mean with this "CAN matrix", but yes a soon as the bus is idle the nodes are allowed to try again to get on the bus by starting the arbitration process with sending the Start of Frame bit and the CAN Id.

CAN does not know masters or slaves. It is called a multi-master system. every node has the same rights on the bus. Higher Layer CAN protocols like CANopen define a Master roler for some kind of network management.

Answer 2

I kind of found the answer here:
CAN bus arbitration backoff time It's written that the masters are free to arbitrate again after the frame of the "arbitration winner" was sent. Does this mean that this decision is coded in the CAN matrix?