Thanks, and i imagine the termination impedance depends on the characteristic impedance of the particular cable?
I am also under the impression that if you are sending say a CAN bus (cable) from one PCB to another...then its sometimes best to have isolators at each board, so that the ground bit in the cable is isolated from the grounds at each PCB...then you provide an isolated PSU to power the "cable side" of the interface ICs. Doing this, prevents ground loops, and ensures that system ground volt drops dont mess up the communication?