BACnet devices share data using BACnet objects over a properly configured BACnet network that carries this data using Ethernet, IP, or MS/TP protocols. At the device level, MS/TP network trunks connect individual BACnet controllers. The BACnet architecture in an I/A Series MicroNet BACnetwork uses these networking protocols, especially MS/TP, to allow communication between controllers and tools either directly over MS/TP or by connecting multiple MS/TP networks using BACnet over IP or Ethernet to form an internetwork with the Plant Controllers and UNCs acting as routers between the networks.