Knowledgebase: Terminology
CAN high / CAN low
Posted by Squarell Technology on 09 December 2013 10:28 AM

CANconsists of two dedicated wires for communication. These wires are called CAN high (CAN_H) and CAN low (CAN_L). When the CANbus is in idle mode, both of these lines carry 2.5V but when data bits are being transmitted, the CAN high line goes to 3.75V and the CAN low drops to 1.25V. This generates a 2.5V voltage differential between the two lines, so the CAN bus is NOT sensitive to inductive spikes, electrical fields or other noise. This makes CANbus very resilient in an electrically noisy environment, like a vehicle. Using twisted-pairs makes it even more robust. The lines must beterminatedat each end with a 120Ω resistor. 

CAN High CANbus wire has an operating voltage between 2,5-3,5V.

CAN Low CANbus wire has an operating voltage between 1,5-2,5V.

CAN high and low voltage levels.



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