BACnet/IP vs BACnet MS/TP for enteliWEB Deployments

Quick Answer

BACnet/IP runs over Ethernet (UDP) at high speed for backbone communication. BACnet MS/TP runs over RS-485 at lower speeds for field-level devices. enteliWEB communicates over BACnet/IP; MS/TP devices are reached through BACnet routers, typically Delta Controls ORCA controllers.

BACnet/IP

BACnet/IP uses standard Ethernet and UDP (port 47808). It supports high-speed communication, multiple simultaneous connections, and leverages existing Ethernet infrastructure. enteliWEB, supervisory controllers, and building-level controllers communicate over BACnet/IP.

BACnet MS/TP

BACnet MS/TP uses RS-485 two-wire serial with a token-passing protocol. It operates at lower speeds (9600-76800 baud) but is cost-effective for field-level devices like VAV box controllers, fan coil units, and zone sensors. MS/TP is still widely used because the wiring is simple (two-conductor twisted pair) and controller costs are lower than IP-enabled devices.

Routing Between IP and MS/TP

Delta Controls ORCA controllers serve as BACnet routers, bridging BACnet/IP backbone traffic to MS/TP field buses. Each ORCA can manage multiple MS/TP segments, routing BACnet messages between enteliWEB (IP) and field devices (MS/TP). For comparison with other field bus protocols, see how DNP3 handles remote device communication in pipeline SCADA.

MS/TP Wiring Guidelines

• Use shielded twisted pair cable (22-18 AWG)
• Maximum segment length: 1200m (4000ft) at 9600 baud
• Maximum 32 devices per segment (practical recommendation)
• Terminate both ends of the bus with 120-ohm resistors
• Daisy-chain topology only — no star or stub connections