This SAE Recommended Practice details the Physical Layer of the Intelligent Transportation Systems (ITS) Data Bus on CAN (IDB-C), which is generally intended for in-vehicle use. It has been developed by the ITS Data Bus (IDB) Physical Layer Subcommittee of the IDB Committee. The objectives of the subcommittee are to develop information reports, recommended practices and standards concerned with the requirements, design, and usage of devices that communicate electronic signals and control information among ITS related components within the vehicle environment.