Which statement best describes the difference between BACnet MS/TP and BACnet IP networks?

Which statement best describes the difference between BACnet MS/TP and BACnet IP networks?

• A. MS/TP is a serial network over RS-485.
• B. IP is a serial network over RS-485.
• C. MS/TP scales better for large networks.
• D. IP cannot support remote access.

Answer: (A)

BACnet MS/TP and BACnet IP differ in how they transport data. MS/TP is a serial network that runs over RS-485, meaning devices share a two- or four-wire serial bus and communicate using a token-passing scheme. This setup is common for on-site, lower-cost networks and works well for smaller to medium-sized installations, but it naturally limits the number of devices per segment and the distance without repeaters. BACnet IP, by contrast, operates over IP networks such as Ethernet, carrying BACnet frames inside IP packets and allowing routing across subnets and even remote sites via standard networking infrastructure. That’s why the statement describing the difference as MS/TP being a serial network over RS-485 is the best fit. The other options mischaracterize the media or capabilities: IP is not a serial RS-485 network; MS/TP does not scale best for large networks; and IP can support remote access.

BACnet MS/TP and BACnet IP differ in how they transport data. MS/TP is a serial network that runs over RS-485, meaning devices share a two- or four-wire serial bus and communicate using a token-passing scheme. This setup is common for on-site, lower-cost networks and works well for smaller to medium-sized installations, but it naturally limits the number of devices per segment and the distance without repeaters. BACnet IP, by contrast, operates over IP networks such as Ethernet, carrying BACnet frames inside IP packets and allowing routing across subnets and even remote sites via standard networking infrastructure.

That’s why the statement describing the difference as MS/TP being a serial network over RS-485 is the best fit. The other options mischaracterize the media or capabilities: IP is not a serial RS-485 network; MS/TP does not scale best for large networks; and IP can support remote access.