The CAN bus setup consists typically of three components.

• Bus line
  The data line consists of a twisted twin wire cable. All CAN stations connect to this line. The connection shall be kept short to avoid any electrical disturbance, electrical reflections on the bus. Therefore the longest line has to be terminated by resistors.
• Load Resistors
  Both ends of the bus line must be terminated with an own load resitor. Common is the usage of 120Ohm resistors depending on the physical layer transceiver used. In this manner the signal quality is increased and reflection on the cable ends are "eaten" by the resistor end. Resistors are not really necessary but recommended, because the failure rate drops and the bus can be used with higher transmission rates.
• CAN stations - CAN Electronic Control Units (ECUs)
  The individual CAN stations are connected to the main line with branch lines forming a shared bus system. They continualy monitor the bus and independently detect which data is relevant and which not. To save costs sometimes the load resistors and the CAN controller are all placed together directly on one mainboard; most times nowadays the CAN controller is integrated into the embedded microdevice/microcontroller unit directly.