Easy CAN BUS Questions

[iso9001]

Hi.... I was looking at my car's wiring diagram and noticed that it has a CAN interface that has twisted pairs... CAN B + and CAN B -

It also has CAN C...

I have some CAN B chips here but was wondering:

Why are there two lines, is it send and recieve ? Thats doesnt seem to make sense... I read CAN was a 1 wire system.

And what is the difference between CAN B and CAN C ??? I see that my car's B runs at 83kbps, is CAN C just faster? Are there any interfaces for CAN C ? (I have a few Pic 18Fs here that say they have CAN B on them)

Thanks

 

[bmcculla]

If I remember correctly CAN is a differential bus - so It has 2 lines but there is only one channel (one line sends asserts the regular signal and the other the inverted signal). Differential busses are more immune to noise- an important consideration for an automotive bus.

 

[Sebi]

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