A detailed explanation would be awesome and or a link to where i might find more info?
Specifically:
what voltage goes from the tx to driver control?
what is the driver control physically?
what is the reciever physcally?

I am giving a short presentation on this on thursday so any help is much appreciated!

Cheers
Mike
Heavy transport Technical Trainer

 

You ask for details, but your question seeking answers is woefully inadequate in the detail department.

Did the maker choose to place their name and a model number somewhere you might be able to retrieve them from?
Details, details details

 

The block diagram shows a CAN transceiver. It is a quasi-differential with respect to a common ground transceiver. What does that mean? It means that the signal is not a true differential signal because both transceivers must have a common ground. If that common ground is, 100 meters long, there could be a significant difference between the two grounds. How much is too much depends on the particular part.

Driver Control sends a signal approaching ground to T1 and a signal approaching Vcc to T2. When it does this CAN_H is actively pulled to Vcc and CAN_L is actively pulled ground. This is the definition of a dominant bit. When Driver Control sends a signal approaching Vcc to T1 and a signal approaching ground to T2, CAN_H and CAN_L both approach Vcc/2 and this is defined as a recessive bit.

Driver Control looks at the value on the TX pin, decides if it is a dominant or recessive bit, and sets the drive levels to T1 & T2 accordingly. It is a combinatorial logic circuit.

The receiver is a differential receiver that is looking at the difference between CAN_H and CAN_L. The actual threshold for detecting a dominant bit is something like (CAN_H - CAN_L) > 1.0V(differential). Anything less than that is a recessive bit.

Here is the datasheet for the NXP 82C251
http://www.nxp.com/docs/en/data-sheet/PCA82C251.pdf