Advantages and disadvantages of the linear bus topology

The linear bus topology offers the CAN bus a range of advantages:

• The wiring complexity is low. This factor plays an especially large role in automobiles.
• An economical and easy to manage twisted wire pair serves as the transmission medium.
• CAN stations can be subsequently added to and removed from the existing CAN bus relatively easily. Only the connection to the bus line must be made or disconnected. This aspect plays a significant role, especially with trouble shooting and repairs.
• The breakdown of a CAN station has no immediate impact on the CAN bus. All the other stations can communicate unconstrained.

The disadvantages of this bus topology have the following effect on the CAN bus:

• The bus line cannot be designed arbitrarily long since the electrical properties (e.g. signal reflections) set physical limits in combination with the transmission speed.
• The same is also valid for the branch lines to the control units in the automobile. Depending on the transmission speed they may not exceed a certain length.
• In order to optimise the signal quality the ends of the bus line must be "terminated"  with load resistors. A cable end which is not correctly terminated can make the entire bus inoperative, especially with a high transmission speed.