This FAQ has been written for NEAL (North East Africa and Levant) region. If you are looking for information for another region, please select the correct country from the top-left dropdown in the page and 'Navigate to Browse FAQs' in the Support menu.
MS/TP
MS/TP is a token-passing local area network (LAN) field bus that is built into all TAC BACnet
controllers. The protocol supports a combination of shared resource and peer-to-peer
communications, where more than one controller can be the network master at any given time.
Electrically, MS/TP adheres to standard RS-485, physically wired using two-conductor shielded
twisted pair cable.
RS-485 Cable Specifications
Cables used to form the RS-485 network should conform to the following specifications:
Wire Size: 22-24 AWG
Cable Type: Twisted-pair, copper wire, tinned
Shield: Braid
Nominal Impedance: 100-120 (
Velocity of propagation: 78%
Capacitance: <12.5 pF/ft between conductors and < 22 pF/ft between the conductor
connected to ground and the next conductor.