SLLA486B May 2020 – October 2024 ISO1042 , ISO1042-Q1 , ISO1044 , ISO1050 , ISOW1044
Since CAN is a differential interface, the entire network will work fine if just two wires for CANH/CANL are interconnected between all nodes of a network, as long as common mode voltage of CAN lines with respect to bus-side ground of the receiving CAN node is within its recommended operating conditions. However, under noisy-system scenarios, best practice is to use a third ground reference line and connect it between all nodes. This way, receiver of each CAN node has a reference, and common mode voltage range will not be violated. If the cable is shielded, the shield can act as a common ground reference with shield connected to earth potential at just one node to avoid any ground loops. Proper system design can ensure large common mode voltages induced on the CAN bus (due to noise pickup) drop across the isolation barrier by connecting the logic-side ground of the isolated CAN transceiver to local ground.