CAN-BUS is a common industrial bus, because it supports a longer travel distance communication medium speed and high reliability. It is commonly found in modern machine tools and automotive diagnostic bus. CAN-BUS expansion board uses the MCP2515 CAN bus controller, SPI interface and MCP2551 CAN transceiver with your Arduino's / Seeeduino communication. With the OBD-II conversion lines and improve OBD-II library, you can create an on-board diagnostic device or a data logger.