Which practical step directly verifies the end-to-end bus resistance with terminators in place?

Which practical step directly verifies the end-to-end bus resistance with terminators in place?

• A. Check the color coding of the cables.
• B. Measure the bus resistance end-to-end with terminators in place (approximately 60 ohms).
• C. Replace terminators with a different resistor value.
• D. Reboot all connected devices to verify network health.

Answer: (B)

The step being tested is directly about verifying the physical termination of the CAN bus. In an NMEA 2000 network, there are 120-ohm terminators at both ends of the main trunk. When you measure end-to-end with both terminators in place, you’re effectively seeing two 120-ohm resistors in parallel, which equals about 60 ohms. This measurement confirms that both terminators are present and that the bus has the correct end-to-end termination, which is essential for proper signal integrity on the route. Color coding only checks the cable appearance, not the electrical characteristics. Replacing terminators with a different value would alter the bus impedance and wouldn’t verify the actual terminating condition. Rebooting devices doesn’t test or confirm the termination or the physical integrity of the bus.

The step being tested is directly about verifying the physical termination of the CAN bus. In an NMEA 2000 network, there are 120-ohm terminators at both ends of the main trunk. When you measure end-to-end with both terminators in place, you’re effectively seeing two 120-ohm resistors in parallel, which equals about 60 ohms. This measurement confirms that both terminators are present and that the bus has the correct end-to-end termination, which is essential for proper signal integrity on the route.

Color coding only checks the cable appearance, not the electrical characteristics. Replacing terminators with a different value would alter the bus impedance and wouldn’t verify the actual terminating condition. Rebooting devices doesn’t test or confirm the termination or the physical integrity of the bus.