Can Communication Signal Generation

Termination circuits (resistors) are connected across the CAN communication system. When transmitting a CAN communication signal, each control unit passes a current to the CAN-H line and the current returns to the CAN-L line.

Fig 1: CAN Communication System Diagram (CAN-H Line And CAN-L Line)
Courtesy of NISSAN NORTH AMERICA, INC.
The current flows separately into the termination circuits connected across the CAN communication system and the termination circuits drop voltage to generate a potential difference between the CAN-H line and the CAN-L line.

Fig 2: CAN-H Line And CAN-L Line Voltage Graph
Courtesy of NISSAN NORTH AMERICA, INC.

NOTE:
A signal with no current passage is called "Recessive" and one with current passage is called "Dominant".
The system produces digital signals for signal communications, by using the potential difference.

Fig 3: CAN Signal Waveform
Courtesy of NISSAN NORTH AMERICA, INC.