[PDF] BACnet Wirin uideines - Price Industries Typically BACnet controllers are networked using the BACnet MS/TP protocol. BACnet MS/TP is based on a physical RS-485 network. Baud rates officially support by ASHRAE 135 are 9600, 19200, 38400, 76800 (and 115,000 is slowly being adopted).[PDF] Bacnet For Beginners2 - Protocol Conversion Page 28. MSTP— An Introduction. This flavor of BAcnet is most commonly used to connect field devices to con- trollers / routers / control applications. The physical layer uses RS485 which allows up to 128 devices to be installed on a single network with a max physical length of 4000ft and speeds up to 115k baud.[PDF] BACnet MS/TP Overview Manual - Neptronic The BACnet MS/TP protocol uses EIA-485 (RS-485) as the physical layer standard for data transmission. Neptronic Controllers also use the BACnet MS/TP protocol over an RS-485 standard for communicating with third party routers, gateways, or master controllers. Wiring The communication wiring must be installed in a proper daisy chain format. BACnet MSTP Installation, RS485 and Cables - Chipkin Automation BACnet MSTP Installation, RS485 and Cables. 8. How many devices to install on a single RS485 Trunk (Bandwidth Issues) How many devices to install on a single RS485 Trunk (Bandwidth Issues) There are non electrical considerations to determine how many devices you put on an MSTP network. The chart below illustrates (from one installation)..