What is CAN bus?

Short for Controller Area Network, an in-vehicle network that connects ECUs using differential signaling on two wires. Lower ID values have higher priority, and when nodes start transmitting at once, non-destructive arbitration leaves a single frame intact. Classical CAN runs at up to 1 Mbit/s, while CAN FD speeds up the data phase to several Mbit/s.

Japanese name: CAN

CAN bus appears in 2 practice questions across 1 topic, including Automotive Semiconductors and Functional Safety.

Field: Automotive Semiconductors and Functional Safety

Try it: questions about CAN bus

On a CAN bus with 120 Ω termination resistors at both ends, the resistance between CAN_H and CAN_L was measured with the power off. Which value is closest to that of a normal bus?

A120 Ω
B240 Ω
C60 Ω

Show answer and explanation

Answer: C. 60 Ω

A CAN bus has a 120 Ω termination resistor at each end to prevent signal reflections. Seen from between CAN_H and CAN_L, the two 120 Ω resistors are in parallel, giving 120 × 120 / (120 + 120) = 60 Ω. A reading of 120 Ω suggests one termination resistor is missing, and around 40 Ω suggests a wiring error such as three termination resistors being fitted. 240 Ω is the mistake of treating the two as being in series.

CAN bus in the explanations

A CAN bus has a 120 Ω termination resistor at each end to prevent signal reflections.
On a CAN bus with 120 Ω termination resistors at both ends,…
On a CAN bus, when 0 (dominant) and 1 (recessive) are driven simultaneously, 0 wins.
In CAN, what happens when two nodes start transmitting fram…

Questions that mention CAN bus (2)

Books on Automotive Semiconductors and Functional Safety Ad

Search Amazon for semiconductor Automotive Semiconductors and Functional Safety

As an Amazon Associate I earn from qualifying purchases.

Back to the glossary