BACnet MSTP Topology

Take care with the topology. The best topology is a single trunk that in-outs on the terminal blocks of each device it connects. What do we mean by best ? We mean the choice which is least likely to cause problems.

Best arrangement. (Showing TX conductor for reference only)

Getting worse. Making the connections to the RS485 terminals, drops instead of connections starts to give the electrical signals all kinds of complicated paths for reflections and harmonics. Its obvious that if the drops are long and are not twisted then you also have more chance to induce noise. (Showing TX conductor for reference only)

Worst. Avoid Star configurations. They are so much harder to debug when it gets tricky. (Showing TX conductor for reference only)