Engineering notes
BACnet/IP or MS/TP: the same word, two kinds of cable
MS/TP rides RS-485. IP rides Ethernet. Floor DDCs often speak MS/TP; the head-end often speaks IP. Without a router the two nets stay mute.
The file writes “BACnet” once. Someone buys MS/TP DDCs, a switch with no VLAN, no router — the IP head-end never sees an object. Same word, two physical layers. It is not “plug and talk”.
MS/TP: twisted pair, termination, MAC, baud — the same pains as RS-485. IP: an Ethernet port, an address, sometimes a BMS VLAN. Many floor DDCs on one MS/TP trunk, then a router onto IP. That router is a schedule line, with a device count if the maker charges for it.
Ask what the floor DDC speaks and what the server speaks. BACnet and Modbus · RS-485 bus