Add-On Device Network for Passenger Cars

Police cars, taxi/cabs, and other special-purpose passenger cars are equipped with add-on devices such as blue-light, special horns, taximeter, digital radio, etc. In the past, such equipment was connected via discrete I/O lines or proprietary interfaces, e.g. RS-232, RS-485, J1850, or CAN. The CAN in Automation (CiA) international users and manufacturers group has established a technical group specifying an open CAN-based network for such car add-on devices. The physical layer is based on ISO 11898-2 (CAN high-speed), and the CAN data link layer (ISO 11898-1) uses the base frame format (11-bit CAN identifier). The selected application layer is compliant to CANopen (EN 50325-4). In order to achieve easy system integration, the group is specifying an application profile describing the content of the transmitted messages.