Same BACnet application layer, two physically incompatible wires — and why a router, not a cable, is what bridges them.
It is easy to hear "MS/TP" and "BACnet/IP" and assume they are two competing building automation protocols, the way BACnet and Modbus are. They are not. Both carry the exact same BACnet application layer — the same objects, the same read/write services, the same data model a supervisory workstation or controller sees. What differs is everything underneath that: BACnet MS/TP (Master-Slave/Token-Passing) carries that application layer over RS-485 twisted-pair serial wiring, while BACnet/IPcarries the identical application layer over standard Ethernet. Both "speak BACnet" — but they are physically incompatible network types, and one cannot simply be wired into the other without a router in between.