I need to know the ability to use RS232 as a physical layer in CANBUS.

 

In a general sense, no. Under some very special circumstances with only two devices on the bus you "might" be able to do some things using the CAN protocol over RS-232.

The thing is that CAN used pullup resistors on the bus as a way of detecting if there is a packet collision. The node with the higher priority address wins the packet arbitration. (CAN bus defines everyone as a Master and Slave, so Collisions are very possible.) In short, RS-232 is not going to cut it for you. CAN goes as far as making silicon to do this packet handling and error correction. Interface chips are cheap, I know you can find a bridge or adapter to interface your computer (or device) to CAN.

~Ken

 

No chance at all.

Heinz

 

CAN bus does not have collisions. It avoids them with the priority arbitration protocol in the CAN ID field. Also, CAN is not a master/slave system. It is peer-to-peer. There are protocols built upon CAN that do define a master/slave relationship, like CAN OPEN, and Device Net, but they are something above CAN and not CAN itself.

As for RS-232, that defines a single-ended bipolar voltage physical layer. CAN is a differential voltage on two lines. If a hybrid were made of CAN and RS-232 it would not be either.

Robert Scott
Real-Time Specialties
Embedded Systems Consulting

 

I am planning to monitor the engine of an 8kw generator's Can-bus over the web via a PC using a Can to RS232 dongle connector from http://www.can232.com

Is that a solution to the above question?

Does any one have experience of using these dongles and/or advice regarding my project?

Thanks.

 

You can use the IC such as DFL-CAN232, which convert CAN Bus to RS232.
Please get detail from http://www.dafulaielectronics.com