Per the NMEA 2000 standard, Instance numbers are pre programmed by the manufacturer and cannot be changed.

• A. True
• B. False
• C. Sometimes
• D. Unknown

Answer: (B)

Instance numbers in NMEA 2000 are used to distinguish multiple data objects of the same parameter group on the bus. They are not fixed forever by the manufacturer; you can configure or change them to reflect the actual device setup. This lets you have multiple identical sensors or data streams (like two tank level sensors or two temperature channels) on the same PGN but with different instance values, such as 0 and 1. The network configuration tools or the device’s own settings typically allow selecting or adjusting these values, so the idea that instance numbers are pre-programmed and unchangeable isn’t correct in general.