Agilent 5991-4166EN Characterizing CAN Bus Arbitration - Application note c20140924 [8] free download

File name 5991-4166EN Characterizing CAN Bus Arbitration - Application note c20140924 [8].pdf

Keysight Technologies Characterizing CAN Bus Arbitration Using InfiniiVision 4000/6000 X-Series Oscilloscope Application Note Introduction The differential CAN bus, which is used extensively in automobiles for drive-train and body control, is based on asynchronous transmission of packets of data from multiple nodes in the system. The CAN bus is also used in many non-automotive applications including control of industrial machinery, as well as medical equipment. Because of the asynchronous nature of packet transmission, there are often collisions of data when two or more nodes begin transmission at the same time... or nearly same time. When collisions occur, although there is a non-destructive bit-wise arbitration process that determines which CAN message has the highest priority to continue data transmission, transmission of lower priority messages can be delayed. In addition, CAN bus error rates can theoretically increase based on the level of bus load and number nodes in the system. This directly affects the frequency-of-occurrence of data collisions. This application note will review the CAN non-destructive bit-wise arbitration process, and will use the InfiniiVision 4000 and 6000 X-Series oscilloscopes to show examples of the following: