In a properly terminated network with power off, what is the resistance reading between NET-H & NET-L?

In a properly terminated network with power off, what is the resistance reading between NET-H & NET-L?

• A. 0 Ohms
• B. 120 Ohms
• C. 30 Ohms
• D. 60 Ohms

Answer: (D)

On a properly terminated NMEA 2000 (CAN) network, there are two 120-ohm termination resistors, one at each end of the bus, connected between CAN-H and CAN-L. When power is off, the transceivers don’t contribute any active paths, so the only path between CAN-H and CAN-L is these two terminators in parallel. The equivalent resistance of two 120-ohm resistors in parallel is 60 ohms, so you should read about 60 ohms. A reading of 120 ohms would suggest only one terminator is present or another path isn’t connected, while a near-zero reading would indicate a short.

On a properly terminated NMEA 2000 (CAN) network, there are two 120-ohm termination resistors, one at each end of the bus, connected between CAN-H and CAN-L. When power is off, the transceivers don’t contribute any active paths, so the only path between CAN-H and CAN-L is these two terminators in parallel. The equivalent resistance of two 120-ohm resistors in parallel is 60 ohms, so you should read about 60 ohms. A reading of 120 ohms would suggest only one terminator is present or another path isn’t connected, while a near-zero reading would indicate a short.