If you are working with CAN communication, you have definitely seen those two 120Ω resistors connected at both ends of the network. Let us understand what role they play in the interface.
CAN bus is a differential transmission line using a twisted pair. The communication signals comprise of CAN_H and CAN_L.To ensure reliable communication, a 120Ω resistor is placed at each physical end of the bus.
- These resistors match the characteristic impedance of the twisted pair (~120Ω)
- These resistors prevent signal reflections that can corrupt communication, eliminating bit errors
- These resistors keep communication stable and noise-free
When a signal travels along the bus and there is no termination present, part of the signal reflects back, causing bit errors, CRC errors, Bus OFF condition.
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