Posted by Rob Drinkwater (CAFTEC) on November 25, 2004, 10:14 pm, in reply to "Re: can bus"
Technicall a computer network could run with two wires, but to give true bi directional routing, the industry intoduced the RJ45 standard, which as you say uses four wires. Prior to this, of course, we used coax cable (2 wires) & BNC connectors for computer networks, but these ran at a tenth or even a hundredth of the speed of a modern 100Mbps or 1 Gbps network.
The CAN bus on a car does not work at this kind of speed, not even hi speed CAN, so a two wire network (+earth of course) is sufficient, as the two wires just give a mirror image to account for interference or noise in the circuit.