Canned Databus

Can bus is a highly sophisticated communication bus.  There are typically two wires, a high (Can H) and a low (Can L).  Can bus' have a great error detecting capability, and a very high transfer rate.  Each device on the bus is connected in parallel on the bus and each device comunicates selectively, and can pick out information sent directly to it.   If I remember right there is no main controller in a canbus system, if two devices start communicating at the exact same time the one that goes low first will win the use of the line for its string. 

The coolest feature of Can (IMO) is that it technically can work if one line is cut, grounded, or shorted to (+) voltage.  The devices will realize that one line has been compromised and switch to a one wire, low speed com protocol. 

Another somewhat cool thing is that Can bus devices will freak out if they are the only device on the line, they don't like talking to themselves!

I hope this helps you in someway, I guess to sum it up Can is just a different protocol.  Its basically considered an industry standard, and is used in cars and lots of other applications.  And, for the record, Can Bus' are serial data bus'

CAN Data. This is easier to find now that I know the right name. Thanks I found a few good sites.

http://www.gmtcny.com/lan.htm

http://www.picotech.com/auto/canbus.htm

http://www.techonline.com/community/ed_resource/feature_article/22590

The bosch site is good too. www.bosch.com  I ordered a free poster, DVD,and manuals from them(in English) Interesting site.

They say by 2008 most vehicles will have the CAN bus. I hope the aftermarket bypass modules will keep up. Some say it will be easier to interface with CAN data in the future?? Have to wait and see..

SAE HS-3000 manual (expensive) and ISO 15765-4 have everything you could want to know about CAN including codes and protocols. The SAE manual also includes VPW and PWM data.

CAN for OBD is mandatory by 2008. Most new cars are CAN now in addition to their old format. If pins 6 and 14 of the J1962 connector are populated its likely to be CAN compatible.

The after market modules should have no problem keeping up. If not, I know what my next CAN project will be.