Hi guys

What is the best way to send more than 8 bytes in CAN? I do know I need to send those in multiple frames, and somehow I need to put them together in the receiver. What information I need to encode in the data field so I can re-assemble the data?

Thanks guys

 

Or something like CAN but it can send more data than 8 bytes.

 

Or connect a CAN transceiver on a UART and roll my own protocol? Anyone tried that?? That will be interesting...

 

The technique you are looking for is called fragmentation. You can check the DeviceNet specification for a description of how they do it. Basically the first byte in the data field consists of a two bit flag and a six bit count. The flag bits are encoded as "First Fragment", "Middle Fragment", "Last Fragment", and "Fragment Acknowledge". The six bit field is a count which starts at zero and rolls over to zero again after 64 fragments. When the consumer consumes a fragment it answers with a "Fragment Ack" and the current fragment counter.

http://www.rtaautomation.com/technologies/devicenet/

Of course you can roll your own protocol, that is what numerous people did. Before you do that it might be worth your while to study one or more previous efforts.

A CAN transceiver on a UART has no particular advantage over an RS-485 transceiver and it has several drawbacks.